/*-

 * HSBmap.c - Create an HSB ramp.

 *

 * Copyright 1995 Sun Microsystems, Inc.  All rights reserved.

 *

 * Permission is hereby granted, free of charge, to any person obtaining a

 * copy of this software and associated documentation files (the

 * "Software"), to deal in the Software without restriction, including

 * without limitation the rights to use, copy, modify, merge, publish,

 * distribute, and/or sell copies of the Software, and to permit persons

 * to whom the Software is furnished to do so, provided that the above

 * copyright notice(s) and this permission notice appear in all copies of

 * the Software and that both the above copyright notice(s) and this

 * permission notice appear in supporting documentation.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS

 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT

 * OF THIRD PARTY RIGHTS. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR

 * HOLDERS INCLUDED IN THIS NOTICE BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL

 * INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING

 * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,

 * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION

 * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

 *

 * Except as contained in this notice, the name of a copyright holder

 * shall not be used in advertising or otherwise to promote the sale, use

 * or other dealings in this Software without prior written authorization

 * of the copyright holder.

 *

 * Author: Patrick J. Naughton

 * [email protected]

 */

#include <sys/types.h>

#include <math.h>

void

hsb2rgb(H, S, B, r, g, b)

    double      H,

                S,

                B;

    u_char     *r,

               *g,

               *b;

{

    register int i;

    register double f,

                bb;

    register u_char p,

                q,

                t;

    H -= floor(H);		/* remove anything over 1 */

    H *= 6.0;

    i = floor(H);		/* 0..5 */

    f = H - (float) i;		/* f = fractional part of H */

    bb = 255.0 * B;

    p = (u_char) (bb * (1.0 - S));

    q = (u_char) (bb * (1.0 - (S * f)));

    t = (u_char) (bb * (1.0 - (S * (1.0 - f))));

    switch (i) {

    case 0:

	*r = (u_char) bb;

	*g = t;

	*b = p;

	break;

    case 1:

	*r = q;

	*g = (u_char) bb;

	*b = p;

	break;

    case 2:

	*r = p;

	*g = (u_char) bb;

	*b = t;

	break;

    case 3:

	*r = p;

	*g = q;

	*b = (u_char) bb;

	break;

    case 4:

	*r = t;

	*g = p;

	*b = (u_char) bb;

	break;

    case 5:

	*r = (u_char) bb;

	*g = p;

	*b = q;

	break;

    }

}

void

HSBramp(h1, s1, b1, h2, s2, b2, start, end, red, green, blue)

    double      h1,

                s1,

                b1,

                h2,

                s2,

                b2;

    int         start,

                end;

    u_char     *red,

               *green,

               *blue;

{

    double      dh,

                ds,

                db;

    register u_char *r,

               *g,

               *b;

    register int i;

    r = red;

    g = green;

    b = blue;

    dh = (h2 - h1) / 255.0;

    ds = (s2 - s1) / 255.0;

    db = (b2 - b1) / 255.0;

    for (i = start; i <= end; i++) {

	hsb2rgb(h1, s1, b1, r++, g++, b++);

	h1 += dh;

	s1 += ds;

	b1 += db;

    }

}