/* Emacs style mode select   -*- C++ -*-
 *-----------------------------------------------------------------------------
 *
 *
 *  PrBoom a Doom port merged with LxDoom and LSDLDoom
 *  based on BOOM, a modified and improved DOOM engine
 *  Copyright (C) 1999 by
 *  id Software, Chi Hoang, Lee Killough, Jim Flynn, Rand Phares, Ty Halderman
 *  Copyright (C) 1999-2000 by
 *  Jess Haas, Nicolas Kalkhof, Colin Phipps, Florian Schulze
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version 2
 *  of the License, or (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 *  02111-1307, USA.
 *
 * DESCRIPTION:
 *   -Loads and initializes texture and flat animation sequences
 *   -Implements utility functions for all linedef/sector special handlers
 *   -Dispatches walkover and gun line triggers
 *   -Initializes and implements special sector types
 *   -Implements donut linedef triggers
 *   -Initializes and implements BOOM linedef triggers for
 *     Scrollers/Conveyors
 *     Friction
 *     Wind/Current
 *
 *-----------------------------------------------------------------------------*/

#include "doomstat.h"
#include "p_spec.h"
#include "p_tick.h"
#include "p_setup.h"
#include "m_random.h"
#include "d_englsh.h"
#include "m_argv.h"
#include "w_wad.h"
#include "r_main.h"
#include "p_maputl.h"
#include "p_map.h"
#include "g_game.h"
#include "p_inter.h"
#include "m_swap.h"
#include "s_sound.h"
#include "sounds.h"
#include "m_bbox.h"                                         // phares 3/20/98
#include "d_deh.h"
#include "r_plane.h"
#include "i_system.h"
#include "rockmacros.h"
//
// Animating textures and planes
// There is another anim_t used in wi_stuff, unrelated.
//
typedef struct
{
   boolean     istexture;
   int         picnum;
   int         basepic;
   int         numpics;
   int         speed;

} anim_t;

//
//      source animation definition
//
//
#ifdef _MSC_VER // proff: This is the same as __attribute__ ((packed)) in GNUC
#pragma pack(push)
#pragma pack(1)
#endif //_MSC_VER

#if defined(__MWERKS__)
#pragma options align=packed
#endif

typedef struct
{
   signed char istexture; //jff 3/23/98 make char for comparison // cph - make signed
   char        endname[9];           //  if false, it is a flat
   char        startname[9];
   int         speed;
} PACKEDATTR animdef_t; //jff 3/23/98 pack to read from memory

#define MAXANIMS 32                   // no longer a strict limit -- killough

anim_t*  lastanim;
 anim_t*  anims;                // new structure w/o limits -- killough
static size_t maxanims;

// killough 3/7/98: Initialize generalized scrolling
static void P_SpawnScrollers(void);

static void P_SpawnFriction(void);    // phares 3/16/98
static void P_SpawnPushers(void);     // phares 3/20/98

extern int allow_pushers;
extern int variable_friction;         // phares 3/20/98

//
// P_InitPicAnims
//
// Load the table of animation definitions, checking for existence of
// the start and end of each frame. If the start doesn't exist the sequence
// is skipped, if the last doesn't exist, BOOM exits.
//
// Wall/Flat animation sequences, defined by name of first and last frame,
// The full animation sequence is given using all lumps between the start
// and end entry, in the order found in the WAD file.
//
// This routine modified to read its data from a predefined lump or
// PWAD lump called ANIMATED rather than a static table in this module to
// allow wad designers to insert or modify animation sequences.
//
// Lump format is an array of byte packed animdef_t structures, terminated
// by a structure with istexture == -1. The lump can be generated from a
// text source file using SWANTBLS.EXE, distributed with the BOOM utils.
// The standard list of switches and animations is contained in the example
// source text file DEFSWANI.DAT also in the BOOM util distribution.
//
//
void P_InitPicAnims (void)
{
   int         i;
   const animdef_t *animdefs; //jff 3/23/98 pointer to animation lump
   int         lump = W_GetNumForName("ANIMATED"); // cph - new wad lump handling
   //  Init animation

   //jff 3/23/98 read from predefined or wad lump instead of table
   animdefs = (const animdef_t *)W_CacheLumpNum(lump);

   lastanim = anims;
   for (i=0 ; animdefs[i].istexture != -1 ; i++)
   {
      // 1/11/98 killough -- removed limit by array-doubling
      if (lastanim >= anims + maxanims)
      {
         size_t newmax = maxanims ? maxanims*2 : MAXANIMS;
         anims = realloc(anims, newmax*sizeof(*anims));   // killough
         lastanim = anims + maxanims;
         maxanims = newmax;
      }

      if (animdefs[i].istexture)
      {
         // different episode ?
         if (R_CheckTextureNumForName(animdefs[i].startname) == -1)
            continue;

         lastanim->picnum = R_TextureNumForName (animdefs[i].endname);
         lastanim->basepic = R_TextureNumForName (animdefs[i].startname);
      }
      else
      {
         if ((W_CheckNumForName)(animdefs[i].startname, ns_flats) == -1)  // killough 4/17/98
            continue;

         lastanim->picnum = R_FlatNumForName (animdefs[i].endname);
         lastanim->basepic = R_FlatNumForName (animdefs[i].startname);
      }

      lastanim->istexture = animdefs[i].istexture;
      lastanim->numpics = lastanim->picnum - lastanim->basepic + 1;

      if (lastanim->numpics < 2)
         I_Error ("P_InitPicAnims: bad cycle from %s to %s",
                  animdefs[i].startname,
                  animdefs[i].endname);

      lastanim->speed = LONG(animdefs[i].speed); // killough 5/5/98: add LONG()
      lastanim++;
   }
   W_UnlockLumpNum(lump);
}

///////////////////////////////////////////////////////////////
//
// Linedef and Sector Special Implementation Utility Functions
//
///////////////////////////////////////////////////////////////

//
// getSide()
//
// Will return a side_t*
//  given the number of the current sector,
//  the line number, and the side (0/1) that you want.
//
// Note: if side=1 is specified, it must exist or results undefined
//
side_t* getSide
( int           currentSector,
  int           line,
  int           side )
{
   return &sides[ (sectors[currentSector].lines[line])->sidenum[side] ];
}


//
// getSector()
//
// Will return a sector_t*
//  given the number of the current sector,
//  the line number and the side (0/1) that you want.
//
// Note: if side=1 is specified, it must exist or results undefined
//
sector_t* getSector
( int           currentSector,
  int           line,
  int           side )
{
   return sides[ (sectors[currentSector].lines[line])->sidenum[side] ].sector;
}


//
// twoSided()
//
// Given the sector number and the line number,
//  it will tell you whether the line is two-sided or not.
//
// modified to return actual two-sidedness rather than presence
// of 2S flag unless compatibility optioned
//
int twoSided
( int   sector,
  int   line )
{
   //jff 1/26/98 return what is actually needed, whether the line
   //has two sidedefs, rather than whether the 2S flag is set

   return comp[comp_model] ?
          (sectors[sector].lines[line])->flags & ML_TWOSIDED
          :
          (sectors[sector].lines[line])->sidenum[1] != -1;
}


//
// getNextSector()
//
// Return sector_t * of sector next to current across line.
//
// Note: returns NULL if not two-sided line, or both sides refer to sector
//
sector_t* getNextSector
( line_t*       line,
  sector_t*     sec )
{
   //jff 1/26/98 check unneeded since line->backsector already
   //returns NULL if the line is not two sided, and does so from
   //the actual two-sidedness of the line, rather than its 2S flag

   if (comp[comp_model])
   {
      if (!(line->flags & ML_TWOSIDED))
         return NULL;
   }

   if (line->frontsector == sec) {
      if (comp[comp_model] || line->backsector!=sec)
         return line->backsector; //jff 5/3/98 don't retn sec unless compatibility
      else                       // fixes an intra-sector line breaking functions
         return NULL;             // like floor->highest floor
   }
   return line->frontsector;
}


//
// P_FindLowestFloorSurrounding()
//
// Returns the fixed point value of the lowest floor height
// in the sector passed or its surrounding sectors.
//
fixed_t P_FindLowestFloorSurrounding(sector_t* sec)
{
   int                 i;
   line_t*             check;
   sector_t*           other;
   fixed_t             floor = sec->floorheight;

   for (i=0 ;i < sec->linecount ; i++)
   {
      check = sec->lines[i];
      other = getNextSector(check,sec);

      if (!other)
         continue;

      if (other->floorheight < floor)
         floor = other->floorheight;
   }
   return floor;
}


//
// P_FindHighestFloorSurrounding()
//
// Passed a sector, returns the fixed point value of the largest
// floor height in the surrounding sectors, not including that passed
//
// NOTE: if no surrounding sector exists -32000*FRACUINT is returned
//       if compatibility then -500*FRACUNIT is the smallest return possible
//
fixed_t P_FindHighestFloorSurrounding(sector_t *sec)
{
   int i;
   line_t* check;
   sector_t* other;
   fixed_t floor = -500*FRACUNIT;

   //jff 1/26/98 Fix initial value for floor to not act differently
   //in sections of wad that are below -500 units
   if (!comp[comp_model])       /* jff 3/12/98 avoid ovf */
      floor = -32000*FRACUNIT;   // in height calculations

   for (i=0 ;i < sec->linecount ; i++)
   {
      check = sec->lines[i];
      other = getNextSector(check,sec);

      if (!other)
         continue;

      if (other->floorheight > floor)
         floor = other->floorheight;
   }
   return floor;
}


//
// P_FindNextHighestFloor()
//
// Passed a sector and a floor height, returns the fixed point value
// of the smallest floor height in a surrounding sector larger than
// the floor height passed. If no such height exists the floorheight
// passed is returned.
//
// Rewritten by Lee Killough to avoid fixed array and to be faster
//
fixed_t P_FindNextHighestFloor(sector_t *sec, int currentheight)
{
   sector_t *other;
   int i;

   for (i=0 ;i < sec->linecount ; i++)
      if ((other = getNextSector(sec->lines[i],sec)) &&
            other->floorheight > currentheight)
      {
         int height = other->floorheight;
         while (++i < sec->linecount)
            if ((other = getNextSector(sec->lines[i],sec)) &&
                  other->floorheight < height &&
                  other->floorheight > currentheight)
               height = other->floorheight;
         return height;
      }
   return currentheight;
}


//
// P_FindNextLowestFloor()
//
// Passed a sector and a floor height, returns the fixed point value
// of the largest floor height in a surrounding sector smaller than
// the floor height passed. If no such height exists the floorheight
// passed is returned.
//
// jff 02/03/98 Twiddled Lee's P_FindNextHighestFloor to make this
//
fixed_t P_FindNextLowestFloor(sector_t *sec, int currentheight)
{
   sector_t *other;
   int i;

   for (i=0 ;i < sec->linecount ; i++)
      if ((other = getNextSector(sec->lines[i],sec)) &&
            other->floorheight < currentheight)
      {
         int height = other->floorheight;
         while (++i < sec->linecount)
            if ((other = getNextSector(sec->lines[i],sec)) &&
                  other->floorheight > height &&
                  other->floorheight < currentheight)
               height = other->floorheight;
         return height;
      }
   return currentheight;
}


//
// P_FindNextLowestCeiling()
//
// Passed a sector and a ceiling height, returns the fixed point value
// of the largest ceiling height in a surrounding sector smaller than
// the ceiling height passed. If no such height exists the ceiling height
// passed is returned.
//
// jff 02/03/98 Twiddled Lee's P_FindNextHighestFloor to make this
//
fixed_t P_FindNextLowestCeiling(sector_t *sec, int currentheight)
{
   sector_t *other;
   int i;

   for (i=0 ;i < sec->linecount ; i++)
      if ((other = getNextSector(sec->lines[i],sec)) &&
            other->ceilingheight < currentheight)
      {
         int height = other->ceilingheight;
         while (++i < sec->linecount)
            if ((other = getNextSector(sec->lines[i],sec)) &&
                  other->ceilingheight > height &&
                  other->ceilingheight < currentheight)
               height = other->ceilingheight;
         return height;
      }
   return currentheight;
}


//
// P_FindNextHighestCeiling()
//
// Passed a sector and a ceiling height, returns the fixed point value
// of the smallest ceiling height in a surrounding sector larger than
// the ceiling height passed. If no such height exists the ceiling height
// passed is returned.
//
// jff 02/03/98 Twiddled Lee's P_FindNextHighestFloor to make this
//
fixed_t P_FindNextHighestCeiling(sector_t *sec, int currentheight)
{
   sector_t *other;
   int i;

   for (i=0 ;i < sec->linecount ; i++)
      if ((other = getNextSector(sec->lines[i],sec)) &&
            other->ceilingheight > currentheight)
      {
         int height = other->ceilingheight;
         while (++i < sec->linecount)
            if ((other = getNextSector(sec->lines[i],sec)) &&
                  other->ceilingheight < height &&
                  other->ceilingheight > currentheight)
               height = other->ceilingheight;
         return height;
      }
   return currentheight;
}


//
// P_FindLowestCeilingSurrounding()
//
// Passed a sector, returns the fixed point value of the smallest
// ceiling height in the surrounding sectors, not including that passed
//
// NOTE: if no surrounding sector exists 32000*FRACUINT is returned
//       but if compatibility then INT_MAX is the return
//
fixed_t P_FindLowestCeilingSurrounding(sector_t* sec)
{
   int                 i;
   line_t*             check;
   sector_t*           other;
   fixed_t             height = INT_MAX;

   /* jff 3/12/98 avoid ovf in height calculations */
   if (!comp[comp_model]) height = 32000*FRACUNIT;

   for (i=0 ;i < sec->linecount ; i++)
   {
      check = sec->lines[i];
      other = getNextSector(check,sec);

      if (!other)
         continue;

      if (other->ceilingheight < height)
         height = other->ceilingheight;
   }
   return height;
}


//
// P_FindHighestCeilingSurrounding()
//
// Passed a sector, returns the fixed point value of the largest
// ceiling height in the surrounding sectors, not including that passed
//
// NOTE: if no surrounding sector exists -32000*FRACUINT is returned
//       but if compatibility then 0 is the smallest return possible
//
fixed_t P_FindHighestCeilingSurrounding(sector_t* sec)
{
   int             i;
   line_t* check;
   sector_t*       other;
   fixed_t height = 0;

   /* jff 1/26/98 Fix initial value for floor to not act differently
    * in sections of wad that are below 0 units
    * jff 3/12/98 avoid ovf in height calculations */
   if (!comp[comp_model]) height = -32000*FRACUNIT;

   for (i=0 ;i < sec->linecount ; i++)
   {
      check = sec->lines[i];
      other = getNextSector(check,sec);

      if (!other)
         continue;

      if (other->ceilingheight > height)
         height = other->ceilingheight;
   }
   return height;
}


//
// P_FindShortestTextureAround()
//
// Passed a sector number, returns the shortest lower texture on a
// linedef bounding the sector.
//
// Note: If no lower texture exists 32000*FRACUNIT is returned.
//       but if compatibility then INT_MAX is returned
//
// jff 02/03/98 Add routine to find shortest lower texture
//
fixed_t P_FindShortestTextureAround(int secnum)
{
   int minsize = INT_MAX;
   side_t*     side;
   int i;
   sector_t *sec = &sectors[secnum];

   if (!comp[comp_model])
      minsize = 32000<<FRACBITS; //jff 3/13/98 prevent overflow in height calcs

   for (i = 0; i < sec->linecount; i++)
   {
      if (twoSided(secnum, i))
      {
         side = getSide(secnum,i,0);
         if (side->bottomtexture > 0)  //jff 8/14/98 texture 0 is a placeholder
            if (textureheight[side->bottomtexture] < minsize)
               minsize = textureheight[side->bottomtexture];
         side = getSide(secnum,i,1);
         if (side->bottomtexture > 0)  //jff 8/14/98 texture 0 is a placeholder
            if (textureheight[side->bottomtexture] < minsize)
               minsize = textureheight[side->bottomtexture];
      }
   }
   return minsize;
}


//
// P_FindShortestUpperAround()
//
// Passed a sector number, returns the shortest upper texture on a
// linedef bounding the sector.
//
// Note: If no upper texture exists 32000*FRACUNIT is returned.
//       but if compatibility then INT_MAX is returned
//
// jff 03/20/98 Add routine to find shortest upper texture
//
fixed_t P_FindShortestUpperAround(int secnum)
{
   int minsize = INT_MAX;
   side_t*     side;
   int i;
   sector_t *sec = &sectors[secnum];

   if (!comp[comp_model])
      minsize = 32000<<FRACBITS; //jff 3/13/98 prevent overflow
   // in height calcs
   for (i = 0; i < sec->linecount; i++)
   {
      if (twoSided(secnum, i))
      {
         side = getSide(secnum,i,0);
         if (side->toptexture > 0)     //jff 8/14/98 texture 0 is a placeholder
            if (textureheight[side->toptexture] < minsize)
               minsize = textureheight[side->toptexture];
         side = getSide(secnum,i,1);
         if (side->toptexture > 0)     //jff 8/14/98 texture 0 is a placeholder
            if (textureheight[side->toptexture] < minsize)
               minsize = textureheight[side->toptexture];
      }
   }
   return minsize;
}


//
// P_FindModelFloorSector()
//
// Passed a floor height and a sector number, return a pointer to a
// a sector with that floor height across the lowest numbered two sided
// line surrounding the sector.
//
// Note: If no sector at that height bounds the sector passed, return NULL
//
// jff 02/03/98 Add routine to find numeric model floor
//  around a sector specified by sector number
// jff 3/14/98 change first parameter to plain height to allow call
//  from routine not using floormove_t
//
sector_t *P_FindModelFloorSector(fixed_t floordestheight,int secnum)
{
   int i;
   sector_t *sec=NULL;
   int linecount;

   sec = &sectors[secnum]; //jff 3/2/98 woops! better do this
   //jff 5/23/98 don't disturb sec->linecount while searching
   // but allow early exit in old demos
   linecount = sec->linecount;
   for (i = 0; i < (demo_compatibility && sec->linecount<linecount?
                    sec->linecount : linecount); i++)
   {
      if ( twoSided(secnum, i) )
      {
         if (getSide(secnum,i,0)->sector-sectors == secnum)
            sec = getSector(secnum,i,1);
         else
            sec = getSector(secnum,i,0);

         if (sec->floorheight == floordestheight)
            return sec;
      }
   }
   return NULL;
}


//
// P_FindModelCeilingSector()
//
// Passed a ceiling height and a sector number, return a pointer to a
// a sector with that ceiling height across the lowest numbered two sided
// line surrounding the sector.
//
// Note: If no sector at that height bounds the sector passed, return NULL
//
// jff 02/03/98 Add routine to find numeric model ceiling
//  around a sector specified by sector number
//  used only from generalized ceiling types
// jff 3/14/98 change first parameter to plain height to allow call
//  from routine not using ceiling_t
//
sector_t *P_FindModelCeilingSector(fixed_t ceildestheight,int secnum)
{
   int i;
   sector_t *sec=NULL;
   int linecount;

   sec = &sectors[secnum]; //jff 3/2/98 woops! better do this
   //jff 5/23/98 don't disturb sec->linecount while searching
   // but allow early exit in old demos
   linecount = sec->linecount;
   for (i = 0; i < (demo_compatibility && sec->linecount<linecount?
                    sec->linecount : linecount); i++)
   {
      if ( twoSided(secnum, i) )
      {
         if (getSide(secnum,i,0)->sector-sectors == secnum)
            sec = getSector(secnum,i,1);
         else
            sec = getSector(secnum,i,0);

         if (sec->ceilingheight == ceildestheight)
            return sec;
      }
   }
   return NULL;
}

//
// RETURN NEXT SECTOR # THAT LINE TAG REFERS TO
//

// Find the next sector with the same tag as a linedef.
// Rewritten by Lee Killough to use chained hashing to improve speed

int P_FindSectorFromLineTag(const line_t *line, int start)
{
   start = start >= 0 ? sectors[start].nexttag :
           sectors[(unsigned) line->tag % (unsigned) numsectors].firsttag;
   while (start >= 0 && sectors[start].tag != line->tag)
      start = sectors[start].nexttag;
   return start;
}

// killough 4/16/98: Same thing, only for linedefs

int P_FindLineFromLineTag(const line_t *line, int start)
{
   start = start >= 0 ? lines[start].nexttag :
           lines[(unsigned) line->tag % (unsigned) numlines].firsttag;
   while (start >= 0 && lines[start].tag != line->tag)
      start = lines[start].nexttag;
   return start;
}

// Hash the sector tags across the sectors and linedefs.
static void P_InitTagLists(void)
{
   register int i;

   for (i=numsectors; --i>=0; )        // Initially make all slots empty.
      sectors[i].firsttag = -1;
   for (i=numsectors; --i>=0; )        // Proceed from last to first sector
   {                                 // so that lower sectors appear first
      int j = (unsigned) sectors[i].tag % (unsigned) numsectors; // Hash func
      sectors[i].nexttag = sectors[j].firsttag;   // Prepend sector to chain
      sectors[j].firsttag = i;
   }

   // killough 4/17/98: same thing, only for linedefs

   for (i=numlines; --i>=0; )        // Initially make all slots empty.
      lines[i].firsttag = -1;
   for (i=numlines; --i>=0; )        // Proceed from last to first linedef
   {                               // so that lower linedefs appear first
      int j = (unsigned) lines[i].tag % (unsigned) numlines; // Hash func
      lines[i].nexttag = lines[j].firsttag;   // Prepend linedef to chain
      lines[j].firsttag = i;
   }
}

//
// P_FindMinSurroundingLight()
//
// Passed a sector and a light level, returns the smallest light level
// in a surrounding sector less than that passed. If no smaller light
// level exists, the light level passed is returned.
//
int P_FindMinSurroundingLight
( sector_t*     sector,
  int           max )
{
   int         i;
   int         min;
   line_t*     line;
   sector_t*   check;

   min = max;
   for (i=0 ; i < sector->linecount ; i++)
   {
      line = sector->lines[i];
      check = getNextSector(line,sector);

      if (!check)
         continue;

      if (check->lightlevel < min)
         min = check->lightlevel;
   }
   return min;
}


//
// P_CanUnlockGenDoor()
//
// Passed a generalized locked door linedef and a player, returns whether
// the player has the keys necessary to unlock that door.
//
// Note: The linedef passed MUST be a generalized locked door type
//       or results are undefined.
//
// jff 02/05/98 routine added to test for unlockability of
//  generalized locked doors
//
boolean P_CanUnlockGenDoor
( line_t* line,
  player_t* player)
{
   // does this line special distinguish between skulls and keys?
   int skulliscard = (line->special & LockedNKeys)>>LockedNKeysShift;

   // determine for each case of lock type if player's keys are adequate
   switch((line->special & LockedKey)>>LockedKeyShift)
   {
   case AnyKey:
      if
      (
         !player->cards[it_redcard] &&
         !player->cards[it_redskull] &&
         !player->cards[it_bluecard] &&
         !player->cards[it_blueskull] &&
         !player->cards[it_yellowcard] &&
         !player->cards[it_yellowskull]
      )
      {
         player->message = s_PD_ANY; // Ty 03/27/98 - externalized
         S_StartSound(player->mo,sfx_oof);             // killough 3/20/98
         return false;
      }
      break;
   case RCard:
      if
      (
         !player->cards[it_redcard] &&
         (!skulliscard || !player->cards[it_redskull])
      )
      {
         player->message = skulliscard? s_PD_REDK : s_PD_REDC; // Ty 03/27/98 - externalized
         S_StartSound(player->mo,sfx_oof);             // killough 3/20/98
         return false;
      }
      break;
   case BCard:
      if
      (
         !player->cards[it_bluecard] &&
         (!skulliscard || !player->cards[it_blueskull])
      )
      {
         player->message = skulliscard? s_PD_BLUEK : s_PD_BLUEC; // Ty 03/27/98 - externalized
         S_StartSound(player->mo,sfx_oof);             // killough 3/20/98
         return false;
      }
      break;
   case YCard:
      if
      (
         !player->cards[it_yellowcard] &&
         (!skulliscard || !player->cards[it_yellowskull])
      )
      {
         player->message = skulliscard? s_PD_YELLOWK : s_PD_YELLOWC; // Ty 03/27/98 - externalized
         S_StartSound(player->mo,sfx_oof);             // killough 3/20/98
         return false;
      }
      break;
   case RSkull:
      if
      (
         !player->cards[it_redskull] &&
         (!skulliscard || !player->cards[it_redcard])
      )
      {
         player->message = skulliscard? s_PD_REDK : s_PD_REDS; // Ty 03/27/98 - externalized
         S_StartSound(player->mo,sfx_oof);             // killough 3/20/98
         return false;
      }
      break;
   case BSkull:
      if
      (
         !player->cards[it_blueskull] &&
         (!skulliscard || !player->cards[it_bluecard])
      )
      {
         player->message = skulliscard? s_PD_BLUEK : s_PD_BLUES; // Ty 03/27/98 - externalized
         S_StartSound(player->mo,sfx_oof);             // killough 3/20/98
         return false;
      }
      break;
   case YSkull:
      if
      (
         !player->cards[it_yellowskull] &&
         (!skulliscard || !player->cards[it_yellowcard])
      )
      {
         player->message = skulliscard? s_PD_YELLOWK : s_PD_YELLOWS; // Ty 03/27/98 - externalized
         S_StartSound(player->mo,sfx_oof);             // killough 3/20/98
         return false;
      }
      break;
   case AllKeys:
      if
      (
         !skulliscard &&
         (
            !player->cards[it_redcard] ||
            !player->cards[it_redskull] ||
            !player->cards[it_bluecard] ||
            !player->cards[it_blueskull] ||
            !player->cards[it_yellowcard] ||
            !player->cards[it_yellowskull]
         )
      )
      {
         player->message = s_PD_ALL6; // Ty 03/27/98 - externalized
         S_StartSound(player->mo,sfx_oof);             // killough 3/20/98
         return false;
      }
      if
      (
         skulliscard &&
         (
            (!player->cards[it_redcard] &&
             !player->cards[it_redskull]) ||
            (!player->cards[it_bluecard] &&
             !player->cards[it_blueskull]) ||
            (!player->cards[it_yellowcard] &&
             !player->cards[it_yellowskull])
         )
      )
      {
         player->message = s_PD_ALL3; // Ty 03/27/98 - externalized
         S_StartSound(player->mo,sfx_oof);             // killough 3/20/98
         return false;
      }
      break;
   }
   return true;
}


//
// P_SectorActive()
//
// Passed a linedef special class (floor, ceiling, lighting) and a sector
// returns whether the sector is already busy with a linedef special of the
// same class. If old demo compatibility true, all linedef special classes
// are the same.
//
// jff 2/23/98 added to prevent old demos from
//  succeeding in starting multiple specials on one sector
//
boolean P_SectorActive(special_e t,sector_t *sec)
{
   if (demo_compatibility)  // return whether any thinker is active
      return sec->floordata || sec->ceilingdata || sec->lightingdata;
   else
      switch (t)             // return whether thinker of same type is active
      {
      case floor_special:
         return (sec->floordata!=NULL);
      case ceiling_special:
         return (sec->ceilingdata!=NULL);
      case lighting_special:
         return (sec->lightingdata!=NULL);
      }
   return true; // don't know which special, must be active, shouldn't be here
}


//
// P_CheckTag()
//
// Passed a line, returns true if the tag is non-zero or the line special
// allows no tag without harm. If compatibility, all linedef specials are
// allowed to have zero tag.
//
// Note: Only line specials activated by walkover, pushing, or shooting are
//       checked by this routine.
//
// jff 2/27/98 Added to check for zero tag allowed for regular special types
//
int P_CheckTag(line_t *line)
{
   /* tag not zero, allowed, or
    * killough 11/98: compatibility option */
   if (comp[comp_zerotags] || line->tag)
      return 1;

   switch(line->special)
   {
   case 1:                 // Manual door specials
   case 26:
   case 27:
   case 28:
   case 31:
   case 32:
   case 33:
   case 34:
   case 117:
   case 118:

   case 139:               // Lighting specials
   case 170:
   case 79:
   case 35:
   case 138:
   case 171:
   case 81:
   case 13:
   case 192:
   case 169:
   case 80:
   case 12:
   case 194:
   case 173:
   case 157:
   case 104:
   case 193:
   case 172:
   case 156:
   case 17:

   case 195:               // Thing teleporters
   case 174:
   case 97:
   case 39:
   case 126:
   case 125:
   case 210:
   case 209:
   case 208:
   case 207:

   case 11:                // Exits
   case 52:
   case 197:
   case 51:
   case 124:
   case 198:

   case 48:                // Scrolling walls
   case 85:
      return 1;   // zero tag allowed

   default:
      break;
   }
   return 0;       // zero tag not allowed
}


//
// P_IsSecret()
//
// Passed a sector, returns if the sector secret type is still active, i.e.
// secret type is set and the secret has not yet been obtained.
//
// jff 3/14/98 added to simplify checks for whether sector is secret
//  in automap and other places
//
boolean P_IsSecret(sector_t *sec)
{
   return (sec->special==9 || (sec->special&SECRET_MASK));
}


//
// P_WasSecret()
//
// Passed a sector, returns if the sector secret type is was active, i.e.
// secret type was set and the secret has been obtained already.
//
// jff 3/14/98 added to simplify checks for whether sector is secret
//  in automap and other places
//
boolean P_WasSecret(sector_t *sec)
{
   return (sec->oldspecial==9 || (sec->oldspecial&SECRET_MASK));
}


//////////////////////////////////////////////////////////////////////////
//
// Events
//
// Events are operations triggered by using, crossing,
// or shooting special lines, or by timed thinkers.
//
/////////////////////////////////////////////////////////////////////////

//
// P_CrossSpecialLine - Walkover Trigger Dispatcher
//
// Called every time a thing origin is about
//  to cross a line with a non 0 special, whether a walkover type or not.
//
// jff 02/12/98 all W1 lines were fixed to check the result from the EV_
//  function before clearing the special. This avoids losing the function
//  of the line, should the sector already be active when the line is
//  crossed. Change is qualified by demo_compatibility.
//
// CPhipps - take a line_t pointer instead of a line number, as in MBF
void P_CrossSpecialLine(line_t *line, int side, mobj_t *thing)
{
   int         ok;

   //  Things that should never trigger lines
   if (!thing->player)
   {
      // Things that should NOT trigger specials...
      switch(thing->type)
      {
      case MT_ROCKET:
      case MT_PLASMA:
      case MT_BFG:
      case MT_TROOPSHOT:
      case MT_HEADSHOT:
      case MT_BRUISERSHOT:
         return;
         break;

      default: break;
      }
   }

   //jff 02/04/98 add check here for generalized lindef types
   if (!demo_compatibility) // generalized types not recognized if old demo
   {
      // pointer to line function is NULL by default, set non-null if
      // line special is walkover generalized linedef type
      int (*linefunc)(line_t *line)=NULL;

      // check each range of generalized linedefs
      if ((unsigned)line->special >= GenEnd)
      {
         // Out of range for GenFloors
      }
      else if ((unsigned)line->special >= GenFloorBase)
      {
         if (!thing->player)
            if ((line->special & FloorChange) || !(line->special & FloorModel))
               return;     // FloorModel is "Allow Monsters" if FloorChange is 0
         if (!line->tag) //jff 2/27/98 all walk generalized types require tag
            return;
         linefunc = EV_DoGenFloor;
      }
      else if ((unsigned)line->special >= GenCeilingBase)
      {
         if (!thing->player)
            if ((line->special & CeilingChange) || !(line->special & CeilingModel))
               return;     // CeilingModel is "Allow Monsters" if CeilingChange is 0
         if (!line->tag) //jff 2/27/98 all walk generalized types require tag
            return;
         linefunc = EV_DoGenCeiling;
      }
      else if ((unsigned)line->special >= GenDoorBase)
      {
         if (!thing->player)
         {
            if (!(line->special & DoorMonster))
               return;                    // monsters disallowed from this door
            if (line->flags & ML_SECRET) // they can't open secret doors either
               return;
         }
         if (!line->tag) //3/2/98 move outside the monster check
            return;
         linefunc = EV_DoGenDoor;
      }
      else if ((unsigned)line->special >= GenLockedBase)
      {
         if (!thing->player)
            return;                     // monsters disallowed from unlocking doors
         if (((line->special&TriggerType)==WalkOnce) || ((line->special&TriggerType)==WalkMany))
         { //jff 4/1/98 check for being a walk type before reporting door type
            if (!P_CanUnlockGenDoor(line,thing->player))
               return;
         }
         else
            return;
         linefunc = EV_DoGenLockedDoor;
      }
      else if ((unsigned)line->special >= GenLiftBase)
      {
         if (!thing->player)
            if (!(line->special & LiftMonster))
               return; // monsters disallowed
         if (!line->tag) //jff 2/27/98 all walk generalized types require tag
            return;
         linefunc = EV_DoGenLift;
      }
      else if ((unsigned)line->special >= GenStairsBase)
      {
         if (!thing->player)
            if (!(line->special & StairMonster))
               return; // monsters disallowed
         if (!line->tag) //jff 2/27/98 all walk generalized types require tag
            return;
         linefunc = EV_DoGenStairs;
      }

      if (linefunc) // if it was a valid generalized type
         switch((line->special & TriggerType) >> TriggerTypeShift)
         {
         case WalkOnce:
            if (linefunc(line))
               line->special = 0;    // clear special if a walk once type
            return;
         case WalkMany:
            linefunc(line);
            return;
         default:                  // if not a walk type, do nothing here
            return;
         }
   }

   if (!thing->player)
   {
      ok = 0;
      switch(line->special)
      {
      case 39:      // teleport trigger
      case 97:      // teleport retrigger
      case 125:     // teleport monsteronly trigger
      case 126:     // teleport monsteronly retrigger
      case 4:       // raise door
      case 10:      // plat down-wait-up-stay trigger
      case 88:      // plat down-wait-up-stay retrigger
         //jff 3/5/98 add ability of monsters etc. to use teleporters
      case 208:     //silent thing teleporters
      case 207:
      case 243:     //silent line-line teleporter
      case 244:     //jff 3/6/98 make fit within DCK's 256 linedef types
      case 262:     //jff 4/14/98 add monster only
      case 263:     //jff 4/14/98 silent thing,line,line rev types
      case 264:     //jff 4/14/98 plus player/monster silent line
      case 265:     //            reversed types
      case 266:
      case 267:
      case 268:
      case 269:
         ok = 1;
         break;
      }
      if (!ok)
         return;
   }

   if (!P_CheckTag(line))  //jff 2/27/98 disallow zero tag on some types
      return;

   // Dispatch on the line special value to the line's action routine
   // If a once only function, and successful, clear the line special

   switch (line->special)
   {
      // Regular walk once triggers

   case 2:
      // Open Door
      if (EV_DoDoor(line,p_open) || demo_compatibility)
         line->special = 0;
      break;

   case 3:
      // Close Door
      if (EV_DoDoor(line,p_close) || demo_compatibility)
         line->special = 0;
      break;

   case 4:
      // Raise Door
      if (EV_DoDoor(line,normal) || demo_compatibility)
         line->special = 0;
      break;

   case 5:
      // Raise Floor
      if (EV_DoFloor(line,raiseFloor) || demo_compatibility)
         line->special = 0;
      break;

   case 6:
      // Fast Ceiling Crush & Raise
      if (EV_DoCeiling(line,fastCrushAndRaise) || demo_compatibility)
         line->special = 0;
      break;

   case 8:
      // Build Stairs
      if (EV_BuildStairs(line,build8) || demo_compatibility)
         line->special = 0;
      break;

   case 10:
      // PlatDownWaitUp
      if (EV_DoPlat(line,downWaitUpStay,0) || demo_compatibility)
         line->special = 0;
      break;

   case 12:
      // Light Turn On - brightest near
      if (EV_LightTurnOn(line,0) || demo_compatibility)
         line->special = 0;
      break;

   case 13:
      // Light Turn On 255
      if (EV_LightTurnOn(line,255) || demo_compatibility)
         line->special = 0;
      break;

   case 16:
      // Close Door 30
      if (EV_DoDoor(line,close30ThenOpen) || demo_compatibility)
         line->special = 0;
      break;

   case 17:
      // Start Light Strobing
      if (EV_StartLightStrobing(line) || demo_compatibility)
         line->special = 0;
      break;

   case 19:
      // Lower Floor
      if (EV_DoFloor(line,lowerFloor) || demo_compatibility)
         line->special = 0;
      break;

   case 22:
      // Raise floor to nearest height and change texture
      if (EV_DoPlat(line,raiseToNearestAndChange,0) || demo_compatibility)
         line->special = 0;
      break;

   case 25:
      // Ceiling Crush and Raise
      if (EV_DoCeiling(line,crushAndRaise) || demo_compatibility)
         line->special = 0;
      break;

   case 30:
      // Raise floor to shortest texture height
      //  on either side of lines.
      if (EV_DoFloor(line,raiseToTexture) || demo_compatibility)
         line->special = 0;
      break;

   case 35:
      // Lights Very Dark
      if (EV_LightTurnOn(line,35) || demo_compatibility)
         line->special = 0;
      break;

   case 36:
      // Lower Floor (TURBO)
      if (EV_DoFloor(line,turboLower) || demo_compatibility)
         line->special = 0;
      break;

   case 37:
      // LowerAndChange
      if (EV_DoFloor(line,lowerAndChange) || demo_compatibility)
         line->special = 0;
      break;

   case 38:
      // Lower Floor To Lowest
      if (EV_DoFloor(line, lowerFloorToLowest) || demo_compatibility)
         line->special = 0;
      break;

   case 39:
      // TELEPORT! //jff 02/09/98 fix using up with wrong side crossing
      if (EV_Teleport(line, side, thing) || demo_compatibility)
         line->special = 0;
      break;

   case 40:
      // RaiseCeilingLowerFloor
      if (demo_compatibility)
      {
         EV_DoCeiling( line, raiseToHighest );
         EV_DoFloor( line, lowerFloorToLowest ); //jff 02/12/98 doesn't work
         line->special = 0;
      }
      else
         if (EV_DoCeiling(line, raiseToHighest))
            line->special = 0;
      break;

   case 44:
      // Ceiling Crush
      if (EV_DoCeiling(line, lowerAndCrush) || demo_compatibility)
         line->special = 0;
      break;

   case 52:
      // EXIT!
      // killough 10/98: prevent zombies from exiting levels
      if (!(thing->player && thing->player->health <= 0 && !comp[comp_zombie]))
         G_ExitLevel ();
      break;

   case 53:
      // Perpetual Platform Raise
      if (EV_DoPlat(line,perpetualRaise,0) || demo_compatibility)
         line->special = 0;
      break;

   case 54:
      // Platform Stop
      if (EV_StopPlat(line) || demo_compatibility)
         line->special = 0;
      break;

   case 56:
      // Raise Floor Crush
      if (EV_DoFloor(line,raiseFloorCrush) || demo_compatibility)
         line->special = 0;
      break;

   case 57:
      // Ceiling Crush Stop
      if (EV_CeilingCrushStop(line) || demo_compatibility)
         line->special = 0;
      break;

   case 58:
      // Raise Floor 24
      if (EV_DoFloor(line,raiseFloor24) || demo_compatibility)
         line->special = 0;
      break;

   case 59:
      // Raise Floor 24 And Change
      if (EV_DoFloor(line,raiseFloor24AndChange) || demo_compatibility)
         line->special = 0;
      break;

   case 100:
      // Build Stairs Turbo 16
      if (EV_BuildStairs(line,turbo16) || demo_compatibility)
         line->special = 0;
      break;

   case 104:
      // Turn lights off in sector(tag)
      if (EV_TurnTagLightsOff(line) || demo_compatibility)
         line->special = 0;
      break;

   case 108:
      // Blazing Door Raise (faster than TURBO!)
      if (EV_DoDoor(line,blazeRaise) || demo_compatibility)
         line->special = 0;
      break;

   case 109:
      // Blazing Door Open (faster than TURBO!)
      if (EV_DoDoor (line,blazeOpen) || demo_compatibility)
         line->special = 0;
      break;

   case 110:
      // Blazing Door Close (faster than TURBO!)
      if (EV_DoDoor (line,blazeClose) || demo_compatibility)
         line->special = 0;
      break;

   case 119:
      // Raise floor to nearest surr. floor
      if (EV_DoFloor(line,raiseFloorToNearest) || demo_compatibility)
         line->special = 0;
      break;

   case 121:
      // Blazing PlatDownWaitUpStay
      if (EV_DoPlat(line,blazeDWUS,0) || demo_compatibility)
         line->special = 0;
      break;

   case 124:
      // Secret EXIT
      // killough 10/98: prevent zombies from exiting levels
      // CPhipps - change for lxdoom's compatibility handling
      if (!(thing->player && thing->player->health <= 0 && !comp[comp_zombie]))
         G_SecretExitLevel ();
      break;

   case 125:
      // TELEPORT MonsterONLY
      if (!thing->player &&
            (EV_Teleport(line, side, thing) || demo_compatibility))
         line->special = 0;
      break;

   case 130:
      // Raise Floor Turbo
      if (EV_DoFloor(line,raiseFloorTurbo) || demo_compatibility)
         line->special = 0;
      break;

   case 141:
      // Silent Ceiling Crush & Raise
      if (EV_DoCeiling(line,silentCrushAndRaise) || demo_compatibility)
         line->special = 0;
      break;

      // Regular walk many retriggerable

   case 72:
      // Ceiling Crush
      EV_DoCeiling( line, lowerAndCrush );
      break;

   case 73:
      // Ceiling Crush and Raise
      EV_DoCeiling(line,crushAndRaise);
      break;

   case 74:
      // Ceiling Crush Stop
      EV_CeilingCrushStop(line);
      break;

   case 75:
      // Close Door
      EV_DoDoor(line,p_close);
      break;

   case 76:
      // Close Door 30
      EV_DoDoor(line,close30ThenOpen);
      break;

   case 77:
      // Fast Ceiling Crush & Raise
      EV_DoCeiling(line,fastCrushAndRaise);
      break;

   case 79:
      // Lights Very Dark
      EV_LightTurnOn(line,35);
      break;

   case 80:
      // Light Turn On - brightest near
      EV_LightTurnOn(line,0);
      break;

   case 81:
      // Light Turn On 255
      EV_LightTurnOn(line,255);
      break;

   case 82:
      // Lower Floor To Lowest
      EV_DoFloor( line, lowerFloorToLowest );
      break;

   case 83:
      // Lower Floor
      EV_DoFloor(line,lowerFloor);
      break;

   case 84:
      // LowerAndChange
      EV_DoFloor(line,lowerAndChange);
      break;

   case 86:
      // Open Door
      EV_DoDoor(line,p_open);
      break;

   case 87:
      // Perpetual Platform Raise
      EV_DoPlat(line,perpetualRaise,0);
      break;

   case 88:
      // PlatDownWaitUp
      EV_DoPlat(line,downWaitUpStay,0);
      break;

   case 89:
      // Platform Stop
      EV_StopPlat(line);
      break;

   case 90:
      // Raise Door
      EV_DoDoor(line,normal);
      break;

   case 91:
      // Raise Floor
      EV_DoFloor(line,raiseFloor);
      break;

   case 92:
      // Raise Floor 24
      EV_DoFloor(line,raiseFloor24);
      break;

   case 93:
      // Raise Floor 24 And Change
      EV_DoFloor(line,raiseFloor24AndChange);
      break;

   case 94:
      // Raise Floor Crush
      EV_DoFloor(line,raiseFloorCrush);
      break;

   case 95:
      // Raise floor to nearest height
      // and change texture.
      EV_DoPlat(line,raiseToNearestAndChange,0);
      break;

   case 96:
      // Raise floor to shortest texture height
      // on either side of lines.
      EV_DoFloor(line,raiseToTexture);
      break;

   case 97:
      // TELEPORT!
      EV_Teleport( line, side, thing );
      break;

   case 98:
      // Lower Floor (TURBO)
      EV_DoFloor(line,turboLower);
      break;

   case 105:
      // Blazing Door Raise (faster than TURBO!)
      EV_DoDoor (line,blazeRaise);
      break;

   case 106:
      // Blazing Door Open (faster than TURBO!)
      EV_DoDoor (line,blazeOpen);
      break;

   case 107:
      // Blazing Door Close (faster than TURBO!)
      EV_DoDoor (line,blazeClose);
      break;

   case 120:
      // Blazing PlatDownWaitUpStay.
      EV_DoPlat(line,blazeDWUS,0);
      break;

   case 126:
      // TELEPORT MonsterONLY.
      if (!thing->player)
         EV_Teleport( line, side, thing );
      break;

   case 128:
      // Raise To Nearest Floor
      EV_DoFloor(line,raiseFloorToNearest);
      break;

   case 129:
      // Raise Floor Turbo
      EV_DoFloor(line,raiseFloorTurbo);
      break;

      // Extended walk triggers

      // jff 1/29/98 added new linedef types to fill all functions out so that
      // all have varieties SR, S1, WR, W1

      // killough 1/31/98: "factor out" compatibility test, by
      // adding inner switch qualified by compatibility flag.
      // relax test to demo_compatibility

      // killough 2/16/98: Fix problems with W1 types being cleared too early

   default:
      if (!demo_compatibility)
         switch (line->special)
         {
            // Extended walk once triggers

         case 142:
            // Raise Floor 512
            // 142 W1  EV_DoFloor(raiseFloor512)
            if (EV_DoFloor(line,raiseFloor512))
               line->special = 0;
            break;

         case 143:
            // Raise Floor 24 and change
            // 143 W1  EV_DoPlat(raiseAndChange,24)
            if (EV_DoPlat(line,raiseAndChange,24))
               line->special = 0;
            break;

         case 144:
            // Raise Floor 32 and change
            // 144 W1  EV_DoPlat(raiseAndChange,32)
            if (EV_DoPlat(line,raiseAndChange,32))
               line->special = 0;
            break;

         case 145:
            // Lower Ceiling to Floor
            // 145 W1  EV_DoCeiling(lowerToFloor)
            if (EV_DoCeiling( line, lowerToFloor ))
               line->special = 0;
            break;

         case 146:
            // Lower Pillar, Raise Donut
            // 146 W1  EV_DoDonut()
            if (EV_DoDonut(line))
               line->special = 0;
            break;

         case 199:
            // Lower ceiling to lowest surrounding ceiling
            // 199 W1 EV_DoCeiling(lowerToLowest)
            if (EV_DoCeiling(line,lowerToLowest))
               line->special = 0;
            break;

         case 200:
            // Lower ceiling to highest surrounding floor
            // 200 W1 EV_DoCeiling(lowerToMaxFloor)
            if (EV_DoCeiling(line,lowerToMaxFloor))
               line->special = 0;
            break;

         case 207:
            // killough 2/16/98: W1 silent teleporter (normal kind)
            if (EV_SilentTeleport(line, side, thing))
               line->special = 0;
            break;

            //jff 3/16/98 renumber 215->153
         case 153: //jff 3/15/98 create texture change no motion type
            // Texture/Type Change Only (Trig)
            // 153 W1 Change Texture/Type Only
            if (EV_DoChange(line,trigChangeOnly))
               line->special = 0;
            break;

         case 239: //jff 3/15/98 create texture change no motion type
            // Texture/Type Change Only (Numeric)
            // 239 W1 Change Texture/Type Only
            if (EV_DoChange(line,numChangeOnly))
               line->special = 0;
            break;

         case 219:
            // Lower floor to next lower neighbor
            // 219 W1 Lower Floor Next Lower Neighbor
            if (EV_DoFloor(line,lowerFloorToNearest))
               line->special = 0;
            break;

         case 227:
            // Raise elevator next floor
            // 227 W1 Raise Elevator next floor
            if (EV_DoElevator(line,elevateUp))
               line->special = 0;
            break;

         case 231:
            // Lower elevator next floor
            // 231 W1 Lower Elevator next floor
            if (EV_DoElevator(line,elevateDown))
               line->special = 0;
            break;

         case 235:
            // Elevator to current floor
            // 235 W1 Elevator to current floor
            if (EV_DoElevator(line,elevateCurrent))
               line->special = 0;
            break;

         case 243: //jff 3/6/98 make fit within DCK's 256 linedef types
            // killough 2/16/98: W1 silent teleporter (linedef-linedef kind)
            if (EV_SilentLineTeleport(line, side, thing, false))
               line->special = 0;
            break;

         case 262: //jff 4/14/98 add silent line-line reversed
            if (EV_SilentLineTeleport(line, side, thing, true))
               line->special = 0;
            break;

         case 264: //jff 4/14/98 add monster-only silent line-line reversed
            if (!thing->player &&
                  EV_SilentLineTeleport(line, side, thing, true))
               line->special = 0;
            break;

         case 266: //jff 4/14/98 add monster-only silent line-line
            if (!thing->player &&
                  EV_SilentLineTeleport(line, side, thing, false))
               line->special = 0;
            break;

         case 268: //jff 4/14/98 add monster-only silent
            if (!thing->player && EV_SilentTeleport(line, side, thing))
               line->special = 0;
            break;

            //jff 1/29/98 end of added W1 linedef types

            // Extended walk many retriggerable

            //jff 1/29/98 added new linedef types to fill all functions
            //out so that all have varieties SR, S1, WR, W1

         case 147:
            // Raise Floor 512
            // 147 WR  EV_DoFloor(raiseFloor512)
            EV_DoFloor(line,raiseFloor512);
            break;

         case 148:
            // Raise Floor 24 and Change
            // 148 WR  EV_DoPlat(raiseAndChange,24)
            EV_DoPlat(line,raiseAndChange,24);
            break;

         case 149:
            // Raise Floor 32 and Change
            // 149 WR  EV_DoPlat(raiseAndChange,32)
            EV_DoPlat(line,raiseAndChange,32);
            break;

         case 150:
            // Start slow silent crusher
            // 150 WR  EV_DoCeiling(silentCrushAndRaise)
            EV_DoCeiling(line,silentCrushAndRaise);
            break;

         case 151:
            // RaiseCeilingLowerFloor
            // 151 WR  EV_DoCeiling(raiseToHighest),
            //         EV_DoFloor(lowerFloortoLowest)
            EV_DoCeiling( line, raiseToHighest );
            EV_DoFloor( line, lowerFloorToLowest );
            break;

         case 152:
            // Lower Ceiling to Floor
            // 152 WR  EV_DoCeiling(lowerToFloor)
            EV_DoCeiling( line, lowerToFloor );
            break;

            //jff 3/16/98 renumber 153->256
         case 256:
            // Build stairs, step 8
            // 256 WR EV_BuildStairs(build8)
            EV_BuildStairs(line,build8);
            break;

            //jff 3/16/98 renumber 154->257
         case 257:
            // Build stairs, step 16
            // 257 WR EV_BuildStairs(turbo16)
            EV_BuildStairs(line,turbo16);
            break;

         case 155:
            // Lower Pillar, Raise Donut
            // 155 WR  EV_DoDonut()
            EV_DoDonut(line);
            break;

         case 156:
            // Start lights strobing
            // 156 WR Lights EV_StartLightStrobing()
            EV_StartLightStrobing(line);
            break;

         case 157:
            // Lights to dimmest near
            // 157 WR Lights EV_TurnTagLightsOff()
            EV_TurnTagLightsOff(line);
            break;

         case 201:
            // Lower ceiling to lowest surrounding ceiling
            // 201 WR EV_DoCeiling(lowerToLowest)
            EV_DoCeiling(line,lowerToLowest);
            break;

         case 202:
            // Lower ceiling to highest surrounding floor
            // 202 WR EV_DoCeiling(lowerToMaxFloor)
            EV_DoCeiling(line,lowerToMaxFloor);
            break;

         case 208:
            // killough 2/16/98: WR silent teleporter (normal kind)
            EV_SilentTeleport(line, side, thing);
            break;

         case 212: //jff 3/14/98 create instant toggle floor type
            // Toggle floor between C and F instantly
            // 212 WR Instant Toggle Floor
            EV_DoPlat(line,toggleUpDn,0);
            break;

            //jff 3/16/98 renumber 216->154
         case 154: //jff 3/15/98 create texture change no motion type
            // Texture/Type Change Only (Trigger)
            // 154 WR Change Texture/Type Only
            EV_DoChange(line,trigChangeOnly);
            break;

         case 240: //jff 3/15/98 create texture change no motion type
            // Texture/Type Change Only (Numeric)
            // 240 WR Change Texture/Type Only
            EV_DoChange(line,numChangeOnly);
            break;

         case 220:
            // Lower floor to next lower neighbor
            // 220 WR Lower Floor Next Lower Neighbor
            EV_DoFloor(line,lowerFloorToNearest);
            break;

         case 228:
            // Raise elevator next floor
            // 228 WR Raise Elevator next floor
            EV_DoElevator(line,elevateUp);
            break;

         case 232:
            // Lower elevator next floor
            // 232 WR Lower Elevator next floor
            EV_DoElevator(line,elevateDown);
            break;

         case 236:
            // Elevator to current floor
            // 236 WR Elevator to current floor
            EV_DoElevator(line,elevateCurrent);
            break;

         case 244: //jff 3/6/98 make fit within DCK's 256 linedef types
            // killough 2/16/98: WR silent teleporter (linedef-linedef kind)
            EV_SilentLineTeleport(line, side, thing, false);
            break;

         case 263: //jff 4/14/98 add silent line-line reversed
            EV_SilentLineTeleport(line, side, thing, true);
            break;

         case 265: //jff 4/14/98 add monster-only silent line-line reversed
            if (!thing->player)
               EV_SilentLineTeleport(line, side, thing, true);
            break;

         case 267: //jff 4/14/98 add monster-only silent line-line
            if (!thing->player)
               EV_SilentLineTeleport(line, side, thing, false);
            break;

         case 269: //jff 4/14/98 add monster-only silent
            if (!thing->player)
               EV_SilentTeleport(line, side, thing);
            break;

            //jff 1/29/98 end of added WR linedef types
         }
      break;
   }
}

//
// P_ShootSpecialLine - Gun trigger special dispatcher
//
// Called when a thing shoots a special line with bullet, shell, saw, or fist.
//
// jff 02/12/98 all G1 lines were fixed to check the result from the EV_
// function before clearing the special. This avoids losing the function
// of the line, should the sector already be in motion when the line is
// impacted. Change is qualified by demo_compatibility.
//
void P_ShootSpecialLine
( mobj_t*       thing,
  line_t*       line )
{
   //jff 02/04/98 add check here for generalized linedef
   if (!demo_compatibility)
   {
      // pointer to line function is NULL by default, set non-null if
      // line special is gun triggered generalized linedef type
      int (*linefunc)(line_t *line)=NULL;

      // check each range of generalized linedefs
      if ((unsigned)line->special >= GenEnd)
      {
         // Out of range for GenFloors
      }
      else if ((unsigned)line->special >= GenFloorBase)
      {
         if (!thing->player)
            if ((line->special & FloorChange) || !(line->special & FloorModel))
               return;   // FloorModel is "Allow Monsters" if FloorChange is 0
         if (!line->tag) //jff 2/27/98 all gun generalized types require tag
            return;

         linefunc = EV_DoGenFloor;
      }
      else if ((unsigned)line->special >= GenCeilingBase)
      {
         if (!thing->player)
            if ((line->special & CeilingChange) || !(line->special & CeilingModel))
               return;   // CeilingModel is "Allow Monsters" if CeilingChange is 0
         if (!line->tag) //jff 2/27/98 all gun generalized types require tag
            return;
         linefunc = EV_DoGenCeiling;
      }
      else if ((unsigned)line->special >= GenDoorBase)
      {
         if (!thing->player)
         {
            if (!(line->special & DoorMonster))
               return;   // monsters disallowed from this door
            if (line->flags & ML_SECRET) // they can't open secret doors either
               return;
         }
         if (!line->tag) //jff 3/2/98 all gun generalized types require tag
            return;
         linefunc = EV_DoGenDoor;
      }
      else if ((unsigned)line->special >= GenLockedBase)
      {
         if (!thing->player)
            return;   // monsters disallowed from unlocking doors
         if (((line->special&TriggerType)==GunOnce) || ((line->special&TriggerType)==GunMany))
         { //jff 4/1/98 check for being a gun type before reporting door type
            if (!P_CanUnlockGenDoor(line,thing->player))
               return;
         }
         else
            return;
         if (!line->tag) //jff 2/27/98 all gun generalized types require tag
            return;

         linefunc = EV_DoGenLockedDoor;
      }
      else if ((unsigned)line->special >= GenLiftBase)
      {
         if (!thing->player)
            if (!(line->special & LiftMonster))
               return; // monsters disallowed
         linefunc = EV_DoGenLift;
      }
      else if ((unsigned)line->special >= GenStairsBase)
      {
         if (!thing->player)
            if (!(line->special & StairMonster))
               return; // monsters disallowed
         if (!line->tag) //jff 2/27/98 all gun generalized types require tag
            return;
         linefunc = EV_DoGenStairs;
      }
      else if ((unsigned)line->special >= GenCrusherBase)
      {
         if (!thing->player)
            if (!(line->special & StairMonster))
               return; // monsters disallowed
         if (!line->tag) //jff 2/27/98 all gun generalized types require tag
            return;
         linefunc = EV_DoGenCrusher;
      }

      if (linefunc)
         switch((line->special & TriggerType) >> TriggerTypeShift)
         {
         case GunOnce:
            if (linefunc(line))
               P_ChangeSwitchTexture(line,0);
            return;
         case GunMany:
            if (linefunc(line))
               P_ChangeSwitchTexture(line,1);
            return;
         default:  // if not a gun type, do nothing here
            return;
         }
   }

   // Impacts that other things can activate.
   if (!thing->player)
   {
      int ok = 0;
      switch(line->special)
      {
      case 46:
         // 46 GR Open door on impact weapon is monster activatable
         ok = 1;
         break;
      }
      if (!ok)
         return;
   }

   if (!P_CheckTag(line))  //jff 2/27/98 disallow zero tag on some types
      return;

   switch(line->special)
   {
   case 24:
      // 24 G1 raise floor to highest adjacent
      if (EV_DoFloor(line,raiseFloor) || demo_compatibility)
         P_ChangeSwitchTexture(line,0);
      break;

   case 46:
      // 46 GR open door, stay open
      EV_DoDoor(line,p_open);
      P_ChangeSwitchTexture(line,1);
      break;

   case 47:
      // 47 G1 raise floor to nearest and change texture and type
      if (EV_DoPlat(line,raiseToNearestAndChange,0) || demo_compatibility)
         P_ChangeSwitchTexture(line,0);
      break;

      //jff 1/30/98 added new gun linedefs here
      // killough 1/31/98: added demo_compatibility check, added inner switch

   default:
      if (!demo_compatibility)
         switch (line->special)
         {
         case 197:
            // Exit to next level
            // killough 10/98: prevent zombies from exiting levels
            if(thing->player && thing->player->health<=0 && !comp[comp_zombie])
               break;
            P_ChangeSwitchTexture(line,0);
            G_ExitLevel();
            break;

         case 198:
            // Exit to secret level
            // killough 10/98: prevent zombies from exiting levels
            if(thing->player && thing->player->health<=0 && !comp[comp_zombie])
               break;
            P_ChangeSwitchTexture(line,0);
            G_SecretExitLevel();
            break;
            //jff end addition of new gun linedefs
         }
      break;
   }
}


//
// P_PlayerInSpecialSector()
//
// Called every tick frame
//  that the player origin is in a special sector
//
// Changed to ignore sector types the engine does not recognize
//
void P_PlayerInSpecialSector (player_t* player)
{
   sector_t*   sector;

   sector = player->mo->subsector->sector;

   // Falling, not all the way down yet?
   // Sector specials don't apply in mid-air
   if (player->mo->z != sector->floorheight)
      return;

   // Has hit ground.
   //jff add if to handle old vs generalized types
   if (sector->special<32) // regular sector specials
   {
      switch (sector->special)
      {
      case 5:
         // 5/10 unit damage per 31 ticks
         if (!player->powers[pw_ironfeet])
            if (!(leveltime&0x1f))
               P_DamageMobj (player->mo, NULL, NULL, 10);
         break;

      case 7:
         // 2/5 unit damage per 31 ticks
         if (!player->powers[pw_ironfeet])
            if (!(leveltime&0x1f))
               P_DamageMobj (player->mo, NULL, NULL, 5);
         break;

      case 16:
         // 10/20 unit damage per 31 ticks
      case 4:
         // 10/20 unit damage plus blinking light (light already spawned)
         if (!player->powers[pw_ironfeet]
               || (P_Random(pr_slimehurt)<5) ) // even with suit, take damage
         {
            if (!(leveltime&0x1f))
               P_DamageMobj (player->mo, NULL, NULL, 20);
         }
         break;

      case 9:
         // Tally player in secret sector, clear secret special
         player->secretcount++;
         sector->special = 0;
         break;

      case 11:
         // Exit on health < 11, take 10/20 damage per 31 ticks
         if (comp[comp_god]) /* killough 2/21/98: add compatibility switch */
            player->cheats &= ~CF_GODMODE; // on godmode cheat clearing
         // does not affect invulnerability
         if (!(leveltime&0x1f))
            P_DamageMobj (player->mo, NULL, NULL, 20);

         if (player->health <= 10)
            G_ExitLevel();
         break;

      default:
         //jff 1/24/98 Don't exit as DOOM2 did, just ignore
         break;
      };
   }
   else //jff 3/14/98 handle extended sector types for secrets and damage
   {
      switch ((sector->special&DAMAGE_MASK)>>DAMAGE_SHIFT)
      {
      case 0: // no damage
         break;
      case 1: // 2/5 damage per 31 ticks
         if (!player->powers[pw_ironfeet])
            if (!(leveltime&0x1f))
               P_DamageMobj (player->mo, NULL, NULL, 5);
         break;
      case 2: // 5/10 damage per 31 ticks
         if (!player->powers[pw_ironfeet])
            if (!(leveltime&0x1f))
               P_DamageMobj (player->mo, NULL, NULL, 10);
         break;
      case 3: // 10/20 damage per 31 ticks
         if (!player->powers[pw_ironfeet]
               || (P_Random(pr_slimehurt)<5))  // take damage even with suit
         {
            if (!(leveltime&0x1f))
               P_DamageMobj (player->mo, NULL, NULL, 20);
         }
         break;
      }
      if (sector->special&SECRET_MASK)
      {
         player->secretcount++;
         sector->special &= ~SECRET_MASK;
         if (sector->special<32) // if all extended bits clear,
            sector->special=0;    // sector is not special anymore
      }

      // phares 3/19/98:
      //
      // If FRICTION_MASK or PUSH_MASK is set, we don't care at this
      // point, since the code to deal with those situations is
      // handled by Thinkers.

   }
}

//
// P_UpdateSpecials()
//
// Check level timer, frag counter,
// animate flats, scroll walls,
// change button textures
//
// Reads and modifies globals:
//  levelTimer, levelTimeCount,
//  levelFragLimit, levelFragLimitCount
//

boolean         levelTimer;
int             levelTimeCount;
boolean         levelFragLimit;      // Ty 03/18/98 Added -frags support
int             levelFragLimitCount; // Ty 03/18/98 Added -frags support

void P_UpdateSpecials (void)
{
   anim_t*     anim;
   int         pic;
   int         i;

   // Downcount level timer, exit level if elapsed
   if (levelTimer == true)
   {
      levelTimeCount--;
      if (!levelTimeCount)
         G_ExitLevel();
   }

   // Check frag counters, if frag limit reached, exit level // Ty 03/18/98
   //  Seems like the total frags should be kept in a simple
   //  array somewhere, but until they are...
   if (levelFragLimit == true)  // we used -frags so compare count
   {
      int k,m,fragcount,exitflag=false;
      for (k=0;k<MAXPLAYERS;k++)
      {
         if (!playeringame[k]) continue;
         fragcount = 0;
         for (m=0;m<MAXPLAYERS;m++)
         {
            if (!playeringame[m]) continue;
            fragcount += (m!=k)?  players[k].frags[m] : -players[k].frags[m];
         }
         if (fragcount >= levelFragLimitCount) exitflag = true;
         if (exitflag == true) break; // skip out of the loop--we're done
      }
      if (exitflag == true)
         G_ExitLevel();
   }

   // Animate flats and textures globally
   for (anim = anims ; anim < lastanim ; anim++)
   {
      for (i=anim->basepic ; i<anim->basepic+anim->numpics ; i++)
      {
         pic = anim->basepic + ( (leveltime/anim->speed + i)%anim->numpics );
         if (anim->istexture)
            texturetranslation[i] = pic;
         else
            flattranslation[i] = pic;
      }
   }

   // Check buttons (retriggerable switches) and change texture on timeout
   for (i = 0; i < MAXBUTTONS; i++)
      if (buttonlist[i].btimer)
      {
         buttonlist[i].btimer--;
         if (!buttonlist[i].btimer)
         {
            switch(buttonlist[i].where)
            {
            case top:
               sides[buttonlist[i].line->sidenum[0]].toptexture =
                  buttonlist[i].btexture;
               break;

            case middle:
               sides[buttonlist[i].line->sidenum[0]].midtexture =
                  buttonlist[i].btexture;
               break;

            case bottom:
               sides[buttonlist[i].line->sidenum[0]].bottomtexture =
                  buttonlist[i].btexture;
               break;
            }
            S_StartSound((mobj_t *)&buttonlist[i].soundorg,sfx_swtchn);
            memset(&buttonlist[i],0,sizeof(button_t));
         }
      }
}

//////////////////////////////////////////////////////////////////////
//
// Sector and Line special thinker spawning at level startup
//
//////////////////////////////////////////////////////////////////////

//
// P_SpawnSpecials
// After the map has been loaded,
//  scan for specials that spawn thinkers
//

// Parses command line parameters.
void P_SpawnSpecials (void)
{
   sector_t*   sector;
   int         i;
   int         episode;

   episode = 1;
   if (W_CheckNumForName("texture2") >= 0)
      episode = 2;

   // See if -timer needs to be used.
   levelTimer = false;

   i = M_CheckParm("-avg");   // Austin Virtual Gaming 20 min timer on DM play
   if (i && deathmatch)
   {
      levelTimer = true;
      levelTimeCount = 20 * 60 * TICRATE;
   }

   i = M_CheckParm("-timer"); // user defined timer on game play
   if (i && deathmatch)
   {
      int time;
      time = atoi(myargv[i+1]) * 60 * TICRATE;
      levelTimer = true;
      levelTimeCount = time;
   }

   // See if -frags has been used
   levelFragLimit = false;
   i = M_CheckParm("-frags");  // Ty 03/18/98 Added -frags support
   if (i && deathmatch)
   {
      int frags;
      frags = atoi(myargv[i+1]);
      if (frags <= 0) frags = 10;  // default 10 if no count provided
      levelFragLimit = true;
      levelFragLimitCount = frags;
   }


   //  Init special sectors.
   sector = sectors;
   for (i=0 ; i<numsectors ; i++, sector++)
   {
      if (!sector->special)
         continue;

      if (sector->special&SECRET_MASK) //jff 3/15/98 count extended
         totalsecret++;                 // secret sectors too

      switch (sector->special&31)
      {
      case 1:
         // random off
         P_SpawnLightFlash (sector);
         break;

      case 2:
         // strobe fast
         P_SpawnStrobeFlash(sector,FASTDARK,0);
         break;

      case 3:
         // strobe slow
         P_SpawnStrobeFlash(sector,SLOWDARK,0);
         break;

      case 4:
         // strobe fast/death slime
         P_SpawnStrobeFlash(sector,FASTDARK,0);
         sector->special |= 3<<DAMAGE_SHIFT; //jff 3/14/98 put damage bits in
         break;

      case 8:
         // glowing light
         P_SpawnGlowingLight(sector);
         break;
      case 9:
         // secret sector
         if (sector->special<32) //jff 3/14/98 bits don't count unless not
            totalsecret++;        // a generalized sector type
         break;

      case 10:
         // door close in 30 seconds
         P_SpawnDoorCloseIn30 (sector);
         break;

      case 12:
         // sync strobe slow
         P_SpawnStrobeFlash (sector, SLOWDARK, 1);
         break;

      case 13:
         // sync strobe fast
         P_SpawnStrobeFlash (sector, FASTDARK, 1);
         break;

      case 14:
         // door raise in 5 minutes
         P_SpawnDoorRaiseIn5Mins (sector, i);
         break;

      case 17:
         // fire flickering
         P_SpawnFireFlicker(sector);
         break;
      }
   }

   P_RemoveAllActiveCeilings();  // jff 2/22/98 use killough's scheme

   P_RemoveAllActivePlats();     // killough

   for (i = 0;i < MAXBUTTONS;i++)
      memset(&buttonlist[i],0,sizeof(button_t));

   // P_InitTagLists() must be called before P_FindSectorFromLineTag()
   // or P_FindLineFromLineTag() can be called.

   P_InitTagLists();   // killough 1/30/98: Create xref tables for tags

   P_SpawnScrollers(); // killough 3/7/98: Add generalized scrollers

   P_SpawnFriction();  // phares 3/12/98: New friction model using linedefs

   P_SpawnPushers();   // phares 3/20/98: New pusher model using linedefs

   for (i=0; i<numlines; i++)
      switch (lines[i].special)
      {
         int s, sec;

         // killough 3/7/98:
         // support for drawn heights coming from different sector
      case 242:
         sec = sides[*lines[i].sidenum].sector-sectors;
         for (s = -1; (s = P_FindSectorFromLineTag(lines+i,s)) >= 0;)
            sectors[s].heightsec = sec;
         break;

         // killough 3/16/98: Add support for setting
         // floor lighting independently (e.g. lava)
      case 213:
         sec = sides[*lines[i].sidenum].sector-sectors;
         for (s = -1; (s = P_FindSectorFromLineTag(lines+i,s)) >= 0;)
            sectors[s].floorlightsec = sec;
         break;

         // killough 4/11/98: Add support for setting
         // ceiling lighting independently
      case 261:
         sec = sides[*lines[i].sidenum].sector-sectors;
         for (s = -1; (s = P_FindSectorFromLineTag(lines+i,s)) >= 0;)
            sectors[s].ceilinglightsec = sec;
         break;

         // killough 10/98:
         //
         // Support for sky textures being transferred from sidedefs.
         // Allows scrolling and other effects (but if scrolling is
         // used, then the same sector tag needs to be used for the
         // sky sector, the sky-transfer linedef, and the scroll-effect
         // linedef). Still requires user to use F_SKY1 for the floor
         // or ceiling texture, to distinguish floor and ceiling sky.

      case 271:   // Regular sky
      case 272:   // Same, only flipped
         for (s = -1; (s = P_FindSectorFromLineTag(lines+i,s)) >= 0;)
            sectors[s].sky = i | PL_SKYFLAT;
         break;
      }
}

// killough 2/28/98:
//
// This function, with the help of r_plane.c and r_bsp.c, supports generalized
// scrolling floors and walls, with optional mobj-carrying properties, e.g.
// conveyor belts, rivers, etc. A linedef with a special type affects all
// tagged sectors the same way, by creating scrolling and/or object-carrying
// properties. Multiple linedefs may be used on the same sector and are
// cumulative, although the special case of scrolling a floor and carrying
// things on it, requires only one linedef. The linedef's direction determines
// the scrolling direction, and the linedef's length determines the scrolling
// speed. This was designed so that an edge around the sector could be used to
// control the direction of the sector's scrolling, which is usually what is
// desired.
//
// Process the active scrollers.
//
// This is the main scrolling code
// killough 3/7/98

void T_Scroll(scroll_t *s)
{
   fixed_t dx = s->dx, dy = s->dy;

   if (s->control != -1)
   {   // compute scroll amounts based on a sector's height changes
      fixed_t height = sectors[s->control].floorheight +
                       sectors[s->control].ceilingheight;
      fixed_t delta = height - s->last_height;
      s->last_height = height;
      dx = FixedMul(dx, delta);
      dy = FixedMul(dy, delta);
   }

   // killough 3/14/98: Add acceleration
   if (s->accel)
   {
      s->vdx = dx += s->vdx;
      s->vdy = dy += s->vdy;
   }

   if (!(dx | dy))                   // no-op if both (x,y) offsets 0
      return;

   switch (s->type)
   {
      side_t *side;
      sector_t *sec;
      fixed_t height, waterheight;  // killough 4/4/98: add waterheight
      msecnode_t *node;
      mobj_t *thing;

   case sc_side:                   // killough 3/7/98: Scroll wall texture
      side = sides + s->affectee;
      side->textureoffset += dx;
      side->rowoffset += dy;
      break;

   case sc_floor:                  // killough 3/7/98: Scroll floor texture
      sec = sectors + s->affectee;
      sec->floor_xoffs += dx;
      sec->floor_yoffs += dy;
      break;

   case sc_ceiling:               // killough 3/7/98: Scroll ceiling texture
      sec = sectors + s->affectee;
      sec->ceiling_xoffs += dx;
      sec->ceiling_yoffs += dy;
      break;

   case sc_carry:

      // killough 3/7/98: Carry things on floor
      // killough 3/20/98: use new sector list which reflects true members
      // killough 3/27/98: fix carrier bug
      // killough 4/4/98: Underwater, carry things even w/o gravity

      sec = sectors + s->affectee;
      height = sec->floorheight;
      waterheight = sec->heightsec != -1 &&
                    sectors[sec->heightsec].floorheight > height ?
                    sectors[sec->heightsec].floorheight : INT_MIN;

      for (node = sec->touching_thinglist; node; node = node->m_snext)
         if (!((thing = node->m_thing)->flags & MF_NOCLIP) &&
               (!(thing->flags & MF_NOGRAVITY || thing->z > height) ||
                thing->z < waterheight))
         {
            // Move objects only if on floor or underwater,
            // non-floating, and clipped.
            thing->momx += dx;
            thing->momy += dy;
         }
      break;

   case sc_carry_ceiling:       // to be added later
      break;
   }
}

//
// Add_Scroller()
//
// Add a generalized scroller to the thinker list.
//
// type: the enumerated type of scrolling: floor, ceiling, floor carrier,
//   wall, floor carrier & scroller
//
// (dx,dy): the direction and speed of the scrolling or its acceleration
//
// control: the sector whose heights control this scroller's effect
//   remotely, or -1 if no control sector
//
// affectee: the index of the affected object (sector or sidedef)
//
// accel: non-zero if this is an accelerative effect
//

static void Add_Scroller(int type, fixed_t dx, fixed_t dy,
                         int control, int affectee, int accel)
{
   scroll_t *s = Z_Malloc(sizeof *s, PU_LEVSPEC, 0);
   s->thinker.function = T_Scroll;
   s->type = type;
   s->dx = dx;
   s->dy = dy;
   s->accel = accel;
   s->vdx = s->vdy = 0;
   if ((s->control = control) != -1)
      s->last_height =
         sectors[control].floorheight + sectors[control].ceilingheight;
   s->affectee = affectee;
   P_AddThinker(&s->thinker);
}

// Adds wall scroller. Scroll amount is rotated with respect to wall's
// linedef first, so that scrolling towards the wall in a perpendicular
// direction is translated into vertical motion, while scrolling along
// the wall in a parallel direction is translated into horizontal motion.
//
// killough 5/25/98: cleaned up arithmetic to avoid drift due to roundoff
//
// killough 10/98:
// fix scrolling aliasing problems, caused by long linedefs causing overflowing

static void Add_WallScroller(fixed_t dx, fixed_t dy, const line_t *l,
                             int control, int accel)
{
   fixed_t x = D_abs(l->dx), y = D_abs(l->dy), d;
   if (y > x)
      d = x, x = y, y = d;
   d = FixedDiv(x, finesine[(tantoangle[FixedDiv(y,x) >> DBITS] + ANG90)
                            >> ANGLETOFINESHIFT]);

   // CPhipps - Import scroller calc overflow fix, compatibility optioned
   if (compatibility_level >= lxdoom_1_compatibility) {
      x = (fixed_t)(((int_64_t)dy * -(int_64_t)l->dy - (int_64_t)dx * (int_64_t)l->dx) / (int_64_t)d);  // killough 10/98:
      y = (fixed_t)(((int_64_t)dy * (int_64_t)l->dx - (int_64_t)dx * (int_64_t)l->dy) / (int_64_t)d);   // Use long long arithmetic
   } else {
      x = -FixedDiv(FixedMul(dy, l->dy) + FixedMul(dx, l->dx), d);
      y = -FixedDiv(FixedMul(dx, l->dy) - FixedMul(dy, l->dx), d);
   }
   Add_Scroller(sc_side, x, y, control, *l->sidenum, accel);
}

// Amount (dx,dy) vector linedef is shifted right to get scroll amount
#define SCROLL_SHIFT 5

// Factor to scale scrolling effect into mobj-carrying properties = 3/32.
// (This is so scrolling floors and objects on them can move at same speed.)
#define CARRYFACTOR ((fixed_t)(FRACUNIT*.09375))

// Initialize the scrollers
static void P_SpawnScrollers(void)
{
   int i;
   line_t *l = lines;

   for (i=0;i<numlines;i++,l++)
   {
      fixed_t dx = l->dx >> SCROLL_SHIFT;  // direction and speed of scrolling
      fixed_t dy = l->dy >> SCROLL_SHIFT;
      int control = -1, accel = 0;         // no control sector or acceleration
      int special = l->special;

      // killough 3/7/98: Types 245-249 are same as 250-254 except that the
      // first side's sector's heights cause scrolling when they change, and
      // this linedef controls the direction and speed of the scrolling. The
      // most complicated linedef since donuts, but powerful :)
      //
      // killough 3/15/98: Add acceleration. Types 214-218 are the same but
      // are accelerative.

      if (special >= 245 && special <= 249)         // displacement scrollers
      {
         special += 250-245;
         control = sides[*l->sidenum].sector - sectors;
      }
      else
         if (special >= 214 && special <= 218)       // accelerative scrollers
         {
            accel = 1;
            special += 250-214;
            control = sides[*l->sidenum].sector - sectors;
         }

      switch (special)
      {
         register int s;

      case 250:   // scroll effect ceiling
         for (s=-1; (s = P_FindSectorFromLineTag(l,s)) >= 0;)
            Add_Scroller(sc_ceiling, -dx, dy, control, s, accel);
         break;

      case 251:   // scroll effect floor
      case 253:   // scroll and carry objects on floor
         for (s=-1; (s = P_FindSectorFromLineTag(l,s)) >= 0;)
            Add_Scroller(sc_floor, -dx, dy, control, s, accel);
         if (special != 253)
            break;

      case 252: // carry objects on floor
         dx = FixedMul(dx,CARRYFACTOR);
         dy = FixedMul(dy,CARRYFACTOR);
         for (s=-1; (s = P_FindSectorFromLineTag(l,s)) >= 0;)
            Add_Scroller(sc_carry, dx, dy, control, s, accel);
         break;

         // killough 3/1/98: scroll wall according to linedef
         // (same direction and speed as scrolling floors)
      case 254:
         for (s=-1; (s = P_FindLineFromLineTag(l,s)) >= 0;)
            if (s != i)
               Add_WallScroller(dx, dy, lines+s, control, accel);
         break;

      case 255:    // killough 3/2/98: scroll according to sidedef offsets
         s = lines[i].sidenum[0];
         Add_Scroller(sc_side, -sides[s].textureoffset,
                      sides[s].rowoffset, -1, s, accel);
         break;

      case 48:                  // scroll first side
         Add_Scroller(sc_side,  FRACUNIT, 0, -1, lines[i].sidenum[0], accel);
         break;

      case 85:                  // jff 1/30/98 2-way scroll
         Add_Scroller(sc_side, -FRACUNIT, 0, -1, lines[i].sidenum[0], accel);
         break;
      }
   }
}

// killough 3/7/98 -- end generalized scroll effects

////////////////////////////////////////////////////////////////////////////
//
// FRICTION EFFECTS
//
// phares 3/12/98: Start of friction effects
//
// As the player moves, friction is applied by decreasing the x and y
// momentum values on each tic. By varying the percentage of decrease,
// we can simulate muddy or icy conditions. In mud, the player slows
// down faster. In ice, the player slows down more slowly.
//
// The amount of friction change is controlled by the length of a linedef
// with type 223. A length < 100 gives you mud. A length > 100 gives you ice.
//
// Also, each sector where these effects are to take place is given a
// new special type _______. Changing the type value at runtime allows
// these effects to be turned on or off.
//
// Sector boundaries present problems. The player should experience these
// friction changes only when his feet are touching the sector floor. At
// sector boundaries where floor height changes, the player can find
// himself still 'in' one sector, but with his feet at the floor level
// of the next sector (steps up or down). To handle this, Thinkers are used
// in icy/muddy sectors. These thinkers examine each object that is touching
// their sectors, looking for players whose feet are at the same level as
// their floors. Players satisfying this condition are given new friction
// values that are applied by the player movement code later.
//
// killough 8/28/98:
//
// Completely redid code, which did not need thinkers, and which put a heavy
// drag on CPU. Friction is now a property of sectors, NOT objects inside
// them. All objects, not just players, are affected by it, if they touch
// the sector's floor. Code simpler and faster, only calling on friction
// calculations when an object needs friction considered, instead of doing
// friction calculations on every sector during every tic.
//
// Although this -might- ruin Boom demo sync involving friction, it's the only
// way, short of code explosion, to fix the original design bug. Fixing the
// design bug in Boom's original friction code, while maintaining demo sync
// under every conceivable circumstance, would double or triple code size, and
// would require maintenance of buggy legacy code which is only useful for old
// demos. Doom demos, which are more important IMO, are not affected by this
// change.
//
/////////////////////////////
//
// Initialize the sectors where friction is increased or decreased

static void P_SpawnFriction(void)
{
   int i;
   line_t *l = lines;

   // killough 8/28/98: initialize all sectors to normal friction first
   for (i = 0; i < numsectors; i++)
   {
      sectors[i].friction = ORIG_FRICTION;
      sectors[i].movefactor = ORIG_FRICTION_FACTOR;
   }

   for (i = 0 ; i < numlines ; i++,l++)
      if (l->special == 223)
      {
         int length = P_AproxDistance(l->dx,l->dy)>>FRACBITS;
         int friction = (0x1EB8*length)/0x80 + 0xD000;
         int movefactor, s;

         // The following check might seem odd. At the time of movement,
         // the move distance is multiplied by 'friction/0x10000', so a
         // higher friction value actually means 'less friction'.

         if (friction > ORIG_FRICTION)       // ice
            movefactor = ((0x10092 - friction)*(0x70))/0x158;
         else
            movefactor = ((friction - 0xDB34)*(0xA))/0x80;

         if (mbf_features)
         { // killough 8/28/98: prevent odd situations
            if (friction > FRACUNIT)
               friction = FRACUNIT;
            if (friction < 0)
               friction = 0;
            if (movefactor < 32)
               movefactor = 32;
         }

         for (s = -1; (s = P_FindSectorFromLineTag(l,s)) >= 0 ; )
         {
            // killough 8/28/98:
            //
            // Instead of spawning thinkers, which are slow and expensive,
            // modify the sector's own friction values. Friction should be
            // a property of sectors, not objects which reside inside them.
            // Original code scanned every object in every friction sector
            // on every tic, adjusting its friction, putting unnecessary
            // drag on CPU. New code adjusts friction of sector only once
            // at level startup, and then uses this friction value.

            sectors[s].friction = friction;
            sectors[s].movefactor = movefactor;
         }
      }
}

//
// phares 3/12/98: End of friction effects
//
////////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////
//
// PUSH/PULL EFFECT
//
// phares 3/20/98: Start of push/pull effects
//
// This is where push/pull effects are applied to objects in the sectors.
//
// There are four kinds of push effects
//
// 1) Pushing Away
//
//    Pushes you away from a point source defined by the location of an
//    MT_PUSH Thing. The force decreases linearly with distance from the
//    source. This force crosses sector boundaries and is felt w/in a circle
//    whose center is at the MT_PUSH. The force is felt only if the point
//    MT_PUSH can see the target object.
//
// 2) Pulling toward
//
//    Same as Pushing Away except you're pulled toward an MT_PULL point
//    source. This force crosses sector boundaries and is felt w/in a circle
//    whose center is at the MT_PULL. The force is felt only if the point
//    MT_PULL can see the target object.
//
// 3) Wind
//
//    Pushes you in a constant direction. Full force above ground, half
//    force on the ground, nothing if you're below it (water).
//
// 4) Current
//
//    Pushes you in a constant direction. No force above ground, full
//    force if on the ground or below it (water).
//
// The magnitude of the force is controlled by the length of a controlling
// linedef. The force vector for types 3 & 4 is determined by the angle
// of the linedef, and is constant.
//
// For each sector where these effects occur, the sector special type has
// to have the PUSH_MASK bit set. If this bit is turned off by a switch
// at run-time, the effect will not occur. The controlling sector for
// types 1 & 2 is the sector containing the MT_PUSH/MT_PULL Thing.


#define PUSH_FACTOR 7

/////////////////////////////
//
// Add a push thinker to the thinker list

static void Add_Pusher(int type, int x_mag, int y_mag, mobj_t* source, int affectee)
{
   pusher_t *p = Z_Malloc(sizeof *p, PU_LEVSPEC, 0);

   p->thinker.function = T_Pusher;
   p->source = source;
   p->type = type;
   p->x_mag = x_mag>>FRACBITS;
   p->y_mag = y_mag>>FRACBITS;
   p->magnitude = P_AproxDistance(p->x_mag,p->y_mag);
   if (source) // point source exist?
   {
      p->radius = (p->magnitude)<<(FRACBITS+1); // where force goes to zero
      p->x = p->source->x;
      p->y = p->source->y;
   }
   p->affectee = affectee;
   P_AddThinker(&p->thinker);
}

/////////////////////////////
//
// PIT_PushThing determines the angle and magnitude of the effect.
// The object's x and y momentum values are changed.
//
// tmpusher belongs to the point source (MT_PUSH/MT_PULL).
//
// killough 10/98: allow to affect things besides players

pusher_t* tmpusher; // pusher structure for blockmap searches

boolean PIT_PushThing(mobj_t* thing)
{
   /* killough 10/98: made more general */
   if (!mbf_features ?
         thing->player && !(thing->flags & (MF_NOCLIP | MF_NOGRAVITY)) :
         (sentient(thing) || thing->flags & MF_SHOOTABLE) &&
         !(thing->flags & MF_NOCLIP))
   {
      angle_t pushangle;
      fixed_t speed;
      fixed_t sx = tmpusher->x;
      fixed_t sy = tmpusher->y;

      speed = (tmpusher->magnitude -
               ((P_AproxDistance(thing->x - sx,thing->y - sy)
                 >>FRACBITS)>>1))<<(FRACBITS-PUSH_FACTOR-1);

      // killough 10/98: make magnitude decrease with square
      // of distance, making it more in line with real nature,
      // so long as it's still in range with original formula.
      //
      // Removes angular distortion, and makes effort required
      // to stay close to source, grow increasingly hard as you
      // get closer, as expected. Still, it doesn't consider z :(

      if (speed > 0 && mbf_features)
      {
         int x = (thing->x-sx) >> FRACBITS;
         int y = (thing->y-sy) >> FRACBITS;
         speed = (int)(((uint_64_t) tmpusher->magnitude << 23) / (x*x+y*y+1));
      }

      // If speed <= 0, you're outside the effective radius. You also have
      // to be able to see the push/pull source point.

      if (speed > 0 && P_CheckSight(thing,tmpusher->source))
      {
         pushangle = R_PointToAngle2(thing->x,thing->y,sx,sy);
         if (tmpusher->source->type == MT_PUSH)
            pushangle += ANG180;    // away
         pushangle >>= ANGLETOFINESHIFT;
         thing->momx += FixedMul(speed,finecosine[pushangle]);
         thing->momy += FixedMul(speed,finesine[pushangle]);
      }
   }
   return true;
}

/////////////////////////////
//
// T_Pusher looks for all objects that are inside the radius of
// the effect.
//

void T_Pusher(pusher_t *p)
{
   sector_t *sec;
   mobj_t   *thing;
   msecnode_t* node;
   int xspeed,yspeed;
   int xl,xh,yl,yh,bx,by;
   int radius;
   int ht = 0;

   if (!allow_pushers)
      return;

   sec = sectors + p->affectee;

   // Be sure the special sector type is still turned on. If so, proceed.
   // Else, bail out; the sector type has been changed on us.

   if (!(sec->special & PUSH_MASK))
      return;

   // For constant pushers (wind/current) there are 3 situations:
   //
   // 1) Affected Thing is above the floor.
   //
   //    Apply the full force if wind, no force if current.
   //
   // 2) Affected Thing is on the ground.
   //
   //    Apply half force if wind, full force if current.
   //
   // 3) Affected Thing is below the ground (underwater effect).
   //
   //    Apply no force if wind, full force if current.

   if (p->type == p_push)
   {

      // Seek out all pushable things within the force radius of this
      // point pusher. Crosses sectors, so use blockmap.

      tmpusher = p; // MT_PUSH/MT_PULL point source
      radius = p->radius; // where force goes to zero
      tmbbox[BOXTOP]    = p->y + radius;
      tmbbox[BOXBOTTOM] = p->y - radius;
      tmbbox[BOXRIGHT]  = p->x + radius;
      tmbbox[BOXLEFT]   = p->x - radius;

      xl = (tmbbox[BOXLEFT] - bmaporgx - MAXRADIUS)>>MAPBLOCKSHIFT;
      xh = (tmbbox[BOXRIGHT] - bmaporgx + MAXRADIUS)>>MAPBLOCKSHIFT;
      yl = (tmbbox[BOXBOTTOM] - bmaporgy - MAXRADIUS)>>MAPBLOCKSHIFT;
      yh = (tmbbox[BOXTOP] - bmaporgy + MAXRADIUS)>>MAPBLOCKSHIFT;
      for (bx=xl ; bx<=xh ; bx++)
         for (by=yl ; by<=yh ; by++)
            P_BlockThingsIterator(bx,by,PIT_PushThing);
      return;
   }

   // constant pushers p_wind and p_current

   if (sec->heightsec != -1) // special water sector?
      ht = sectors[sec->heightsec].floorheight;
   node = sec->touching_thinglist; // things touching this sector
   for ( ; node ; node = node->m_snext)
   {
      thing = node->m_thing;
      if (!thing->player || (thing->flags & (MF_NOGRAVITY | MF_NOCLIP)))
         continue;
      if (p->type == p_wind)
      {
         if (sec->heightsec == -1) // NOT special water sector
            if (thing->z > thing->floorz) // above ground
            {
               xspeed = p->x_mag; // full force
               yspeed = p->y_mag;
            }
            else // on ground
            {
               xspeed = (p->x_mag)>>1; // half force
               yspeed = (p->y_mag)>>1;
            }
         else // special water sector
         {
            if (thing->z > ht) // above ground
            {
               xspeed = p->x_mag; // full force
               yspeed = p->y_mag;
            }
            else if (thing->player->viewz < ht) // underwater
               xspeed = yspeed = 0; // no force
            else // wading in water
            {
               xspeed = (p->x_mag)>>1; // half force
               yspeed = (p->y_mag)>>1;
            }
         }
      }
      else // p_current
      {
         if (sec->heightsec == -1) // NOT special water sector
            if (thing->z > sec->floorheight) // above ground
               xspeed = yspeed = 0; // no force
            else // on ground
            {
               xspeed = p->x_mag; // full force
               yspeed = p->y_mag;
            }
         else // special water sector
            if (thing->z > ht) // above ground
               xspeed = yspeed = 0; // no force
            else // underwater
            {
               xspeed = p->x_mag; // full force
               yspeed = p->y_mag;
            }
      }
      thing->momx += xspeed<<(FRACBITS-PUSH_FACTOR);
      thing->momy += yspeed<<(FRACBITS-PUSH_FACTOR);
   }
}

/////////////////////////////
//
// P_GetPushThing() returns a pointer to an MT_PUSH or MT_PULL thing,
// NULL otherwise.

mobj_t* P_GetPushThing(int s)
{
   mobj_t* thing;
   sector_t* sec;

   sec = sectors + s;
   thing = sec->thinglist;
   while (thing)
   {
      switch(thing->type)
      {
      case MT_PUSH:
      case MT_PULL:
         return thing;
      default:
         break;
      }
      thing = thing->snext;
   }
   return NULL;
}

/////////////////////////////
//
// Initialize the sectors where pushers are present
//

static void P_SpawnPushers(void)
{
   int i;
   line_t *l = lines;
   register int s;
   mobj_t* thing;

   for (i = 0 ; i < numlines ; i++,l++)
      switch(l->special)
      {
      case 224: // wind
         for (s = -1; (s = P_FindSectorFromLineTag(l,s)) >= 0 ; )
            Add_Pusher(p_wind,l->dx,l->dy,NULL,s);
         break;
      case 225: // current
         for (s = -1; (s = P_FindSectorFromLineTag(l,s)) >= 0 ; )
            Add_Pusher(p_current,l->dx,l->dy,NULL,s);
         break;
      case 226: // push/pull
         for (s = -1; (s = P_FindSectorFromLineTag(l,s)) >= 0 ; )
         {
            thing = P_GetPushThing(s);
            if (thing) // No MT_P* means no effect
               Add_Pusher(p_push,l->dx,l->dy,thing,s);
         }
         break;
      }
}

//
// phares 3/20/98: End of Pusher effects
//
////////////////////////////////////////////////////////////////////////////