/*

 * 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;

    }

}