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/* xscreensaver, Copyright (c) 1992, 1997 Jamie Zawinski <jwz@jwz.org>
*
* Permission to use, copy, modify, distribute, and sell this software and its
* documentation for any purpose is hereby granted without fee, provided that
* the above copyright notice appear in all copies and that both that
* copyright notice and this permission notice appear in supporting
* documentation. No representations are made about the suitability of this
* software for any purpose. It is provided "as is" without express or
* implied warranty.
*/
/* This file contains some utility routines for randomly picking the colors
to hack the screen with.
*/
#include "utils.h"
#include "hsv.h"
void
hsv_to_rgb (int h, double s, double v,
unsigned short *r, unsigned short *g, unsigned short *b)
{
double H, S, V, R, G, B;
double p1, p2, p3;
double f;
int i;
if (s < 0) s = 0;
if (v < 0) v = 0;
if (s > 1) s = 1;
if (v > 1) v = 1;
S = s; V = v;
H = (h % 360) / 60.0;
i = H;
f = H - i;
p1 = V * (1 - S);
p2 = V * (1 - (S * f));
p3 = V * (1 - (S * (1 - f)));
if (i == 0) { R = V; G = p3; B = p1; }
else if (i == 1) { R = p2; G = V; B = p1; }
else if (i == 2) { R = p1; G = V; B = p3; }
else if (i == 3) { R = p1; G = p2; B = V; }
else if (i == 4) { R = p3; G = p1; B = V; }
else { R = V; G = p1; B = p2; }
*r = R * 65535;
*g = G * 65535;
*b = B * 65535;
}
void
rgb_to_hsv (unsigned short r, unsigned short g, unsigned short b,
int *h, double *s, double *v)
{
double R, G, B, H, S, V;
double cmax, cmin;
double cmm;
int imax;
R = ((double) r) / 65535.0;
G = ((double) g) / 65535.0;
B = ((double) b) / 65535.0;
cmax = R; cmin = G; imax = 1;
if ( cmax < G ) { cmax = G; cmin = R; imax = 2; }
if ( cmax < B ) { cmax = B; imax = 3; }
if ( cmin > B ) { cmin = B; }
cmm = cmax - cmin;
V = cmax;
if (cmm == 0)
S = H = 0;
else
{
S = cmm / cmax;
if (imax == 1) H = (G - B) / cmm;
else if (imax == 2) H = 2.0 + (B - R) / cmm;
else /*if (imax == 3)*/ H = 4.0 + (R - G) / cmm;
if (H < 0) H += 6.0;
}
*h = (H * 60.0);
*s = S;
*v = V;
}
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