#ifndef lint
static char sccsid[] = "@(#)hsvrgb.c 9.2 88/01/19 Copyright 1985 Sun Micro";
#endif

/*
 * Copyright (c) 1985 by Sun Microsystems, Inc. 
 */

/*-
	Convert between hue/saturation/brightness and red/green/blue

	hsvrgb.c, Mon Jun 24 21:42:13 1985


		These were borrowed from some code by D C Martin
		and minimally adapted.
 */

#ifdef REF
#include <sys/types.h>
#include <ref/config.h>
#endif
#include "shape.h"

/*
 * Convert red/green/blue to hue/saturation/brightness.
 */
cs_frcolortohsb(color, huep, saturationp, brightnessp)
    struct color color;
    fract      *huep,
               *saturationp,
               *brightnessp;
{
    unsigned char cmax, cmin;
    fract       redc,
                greenc,
                bluec;
    cmax = color.red > color.green ? color.red : color.green;
    if (color.blue > cmax)
	cmax = color.blue;
    cmin = color.red < color.green ? color.red : color.green;
    if (color.blue < cmin)
	cmin = color.blue;
    *brightnessp = fraction(cmax,0xFF);
    if (cmax != 0)
	*saturationp = fraction(cmax - cmin, cmax);
    else
	*saturationp = 0;
    if (*saturationp == 0)
	*huep = 0;
    else {
	redc = frdiv(fracti(cmax - color.red), fracti(cmax - cmin));
	greenc = frdiv(fracti(cmax - color.green), fracti(cmax - cmin));
	bluec = frdiv(fracti(cmax - color.blue), fracti(cmax - cmin));
	if (color.red == cmax)
	    *huep = bluec - greenc;
	else if (color.green == cmax)
	    *huep = fracti(2) + redc - bluec;
	else
	    *huep = fracti(4) + greenc - redc;
	*huep = *huep / 6;
	if (*huep < 0)
	    *huep += fracti(1);
    }
}

/*
 * Convert hue/saturation/brightness to red/green/blue color struct.
 */
struct color
cs_frhsbcolor(hue, saturation, brightness)
    fract       hue,
                saturation,
                brightness;
{
    int         i, f;
    fract       p, q, t;
    fract       red, green, blue;
    struct color color;
    if (saturation == 0)
	red = green = blue = brightness;
    else {
	hue = (hue & (fracti(1) - 1)) * 6;
	i = cfloorfr(hue);
	f = hue & (fracti(1) - 1);
	p = frmul(brightness, fracti(1) - saturation);
	q = frmul(brightness, fracti(1) - frmul(saturation, f));
	t = frmul(brightness, (fracti(1) - frmul(saturation, fracti(1) - f)));
	switch (i) {
	case 0:
	    red = brightness;
	    green = t;
	    blue = p;
	    break;
	case 1:
	    red = q;
	    green = brightness;
	    blue = p;
	    break;
	case 2:
	    red = p;
	    green = brightness;
	    blue = t;
	    break;
	case 3:
	    red = p;
	    green = q;
	    blue = brightness;
	    break;
	case 4:
	    red = t;
	    green = p;
	    blue = brightness;
	    break;
	case 5:
	    red = brightness;
	    green = p;
	    blue = q;
	    break;
	}
    }
    red *= 0xFF;
    color.red = cfloorfr(red) < 0xFF ? cfloorfr(red) : 0xFF;
    green *= 0xFF;
    color.green = cfloorfr(green) < 0xFF ? cfloorfr(green) : 0xFF;
    blue *= 0xFF;
    color.blue = cfloorfr(blue) < 0xFF ? cfloorfr(blue) : 0xFF;
    color.hint = sh_colorhint(&color);
    return color;
}

/*
 * Convert red/green/blue to color struct.
 */
struct color
cs_frrgbcolor(red, green, blue)
    fract       red, green, blue;
{
    struct color color;
    red *= 0xFF;
    color.red = cfloorfr(red) < 0xFF ? cfloorfr(red) : 0xFF;
    green *= 0xFF;
    color.green = cfloorfr(green) < 0xFF ? cfloorfr(green) : 0xFF;
    blue *= 0xFF;
    color.blue = cfloorfr(blue) < 0xFF ? cfloorfr(blue) : 0xFF;
    color.hint = sh_colorhint(&color);
    return color;
}