hsbramp.c revision 919
/*
* 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 1994 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*
* 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>
void
hsb2rgb(H, S, B, r, g, b)
double H,
S,
B;
u_char *r,
*g,
*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(h1, s1, b1, h2, s2, b2, count, red, green, blue)
double h1,
s1,
b1,
h2,
s2,
b2;
int count;
u_char *red,
*green,
*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;
}
}