/*
 * Copyright (c) 1988-91 by Patrick J. Naughton.
 *
 * Permission to use, copy, modify, and distribute this software and its
 * documentation for any purpose and without fee is hereby granted,
 * provided that the above copyright notice appear in all copies and that
 * both that copyright notice and this permission notice appear in
 * supporting documentation.
 *
 * This file is provided AS IS with no warranties of any kind.  The author
 * shall have no liability with respect to the infringement of copyrights,
 * trade secrets or any patents by this file or any part thereof.  In no
 * event will the author be liable for any lost revenue or profits or
 * other special, indirect and consequential damages.
 */

/*
 * Copyright (c) 1988, 2011, Oracle and/or its affiliates. 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, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * 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.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

/*-
 * hsbramp.c - Create an HSB ramp.
 *
 * Copyright (c) 1991 by Patrick J. Naughton.
 *
 * See xlock.c for copying information.
 *
 * Revision History:
 * 29-Jul-90: renamed hsbramp.c from HSBmap.c
 *	      minor optimizations.
 * 01-Sep-88: Written.
 */

#include <sys/types.h>
#include <math.h>

static void
hsb2rgb(
    double      H,
    double      S,
    double      B,
    u_char     *r,
    u_char     *g,
    u_char     *b)
{
    int         i;
    double      f;
    double      bb;
    u_char      p;
    u_char      q;
    u_char      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;
    }
}


/*
 * Input is two points in HSB color space and a count
 * of how many discreet rgb space values the caller wants.
 *
 * Output is that many rgb triples which describe a linear
 * interpolate ramp between the two input colors.
 */

void
hsbramp(
    double      h1,
    double      s1,
    double      b1,
    double      h2,
    double      s2,
    double      b2,
    int         count,

    u_char     *red,
    u_char     *green,
    u_char     *blue)
{
    double      dh;
    double      ds;
    double      db;

    dh = (h2 - h1) / count;
    ds = (s2 - s1) / count;
    db = (b2 - b1) / count;
    while (count--) {
	hsb2rgb(h1, s1, b1, red++, green++, blue++);
	h1 += dh;
	s1 += ds;
	b1 += db;
    }
}