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/*
* Motif Tools Library, Version 3.1
* $Id$
*
* Written by David Flanagan.
* Copyright (c) 1992-2001 by David Flanagan.
* All Rights Reserved. See the file COPYRIGHT for details.
* This is open source software. See the file LICENSE for details.
* There is no warranty for this software. See NO_WARRANTY for details.
*
* $Log$
* Revision 1.1.1.1 2001/07/18 11:06:02 root
* Initial checkin.
*
* Revision 1.2 2001/06/12 16:25:28 andre
* *** empty log message ***
*
*
*/
#include <Xmt/Xmt.h>
/*
* RGB <--> HSL conversions were modified from code with the
* following attributions;
*
* A Fast HSL-to-RGB Transform
* by Ken Fishkin, Pixar Inc., January 1989.
* from "Graphics Gems", Academic Press, 1990
*/
/*
* 0 <= h <= 359
* 0 <= s,l <= 100
* 0 <= r,g,b <= 65535
*/
#if NeedFunctionPrototypes
void XmtHSLToRGB(unsigned h, unsigned s, unsigned l,
unsigned *r, unsigned *g, unsigned *b)
#else
void XmtHSLToRGB(h, s, l, r, g, b)
unsigned int h;
unsigned int s;
unsigned int l;
unsigned int *r;
unsigned int *g;
unsigned int *b;
#endif
{
int v;
int m, sv, fract, vsf, mid1, mid2, sextant;
v = (l < 50) ? (l * (s + 100) / 100) : (l + s - (l * s / 100));
if (v <= 0) { *r = *g = *b = 0; return;}
m = l + l - v;
sv = 100 * (v - m) / v;
sextant = h/60;
fract = 100 * (h - (sextant * 60)) / 60;
vsf = v * sv * fract / 10000;
mid1 = m + vsf;
mid2 = v - vsf;
switch (sextant) {
case 0: *r = v; *g = mid1; *b = m; break;
case 1: *r = mid2; *g = v; *b = m; break;
case 2: *r = m; *g = v; *b = mid1; break;
case 3: *r = m; *g = mid2; *b = v; break;
case 4: *r = mid1; *g = m; *b = v; break;
case 5: *r = v; *g = m; *b = mid2; break;
}
*r = (*r * 65535) / 100;
*g = (*g * 65535) / 100;
*b = (*b * 65535) / 100;
}
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