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3144ee8a AT |
1 | /* xscreensaver, Copyright (c) 1992, 1997 Jamie Zawinski <jwz@jwz.org> |
2 | * | |
3 | * Permission to use, copy, modify, distribute, and sell this software and its | |
4 | * documentation for any purpose is hereby granted without fee, provided that | |
5 | * the above copyright notice appear in all copies and that both that | |
6 | * copyright notice and this permission notice appear in supporting | |
7 | * documentation. No representations are made about the suitability of this | |
8 | * software for any purpose. It is provided "as is" without express or | |
9 | * implied warranty. | |
10 | */ | |
11 | ||
12 | /* This file contains some utility routines for randomly picking the colors | |
13 | to hack the screen with. | |
14 | */ | |
15 | ||
16 | #include "utils.h" | |
17 | #include "hsv.h" | |
18 | ||
19 | void | |
20 | hsv_to_rgb (int h, double s, double v, | |
21 | unsigned short *r, unsigned short *g, unsigned short *b) | |
22 | { | |
23 | double H, S, V, R, G, B; | |
24 | double p1, p2, p3; | |
25 | double f; | |
26 | int i; | |
27 | ||
28 | if (s < 0) s = 0; | |
29 | if (v < 0) v = 0; | |
30 | if (s > 1) s = 1; | |
31 | if (v > 1) v = 1; | |
32 | ||
33 | S = s; V = v; | |
34 | H = (h % 360) / 60.0; | |
35 | i = H; | |
36 | f = H - i; | |
37 | p1 = V * (1 - S); | |
38 | p2 = V * (1 - (S * f)); | |
39 | p3 = V * (1 - (S * (1 - f))); | |
40 | if (i == 0) { R = V; G = p3; B = p1; } | |
41 | else if (i == 1) { R = p2; G = V; B = p1; } | |
42 | else if (i == 2) { R = p1; G = V; B = p3; } | |
43 | else if (i == 3) { R = p1; G = p2; B = V; } | |
44 | else if (i == 4) { R = p3; G = p1; B = V; } | |
45 | else { R = V; G = p1; B = p2; } | |
46 | *r = R * 65535; | |
47 | *g = G * 65535; | |
48 | *b = B * 65535; | |
49 | } | |
50 | ||
51 | void | |
52 | rgb_to_hsv (unsigned short r, unsigned short g, unsigned short b, | |
53 | int *h, double *s, double *v) | |
54 | { | |
55 | double R, G, B, H, S, V; | |
56 | double cmax, cmin; | |
57 | double cmm; | |
58 | int imax; | |
59 | R = ((double) r) / 65535.0; | |
60 | G = ((double) g) / 65535.0; | |
61 | B = ((double) b) / 65535.0; | |
62 | cmax = R; cmin = G; imax = 1; | |
63 | if ( cmax < G ) { cmax = G; cmin = R; imax = 2; } | |
64 | if ( cmax < B ) { cmax = B; imax = 3; } | |
65 | if ( cmin > B ) { cmin = B; } | |
66 | cmm = cmax - cmin; | |
67 | V = cmax; | |
68 | if (cmm == 0) | |
69 | S = H = 0; | |
70 | else | |
71 | { | |
72 | S = cmm / cmax; | |
73 | if (imax == 1) H = (G - B) / cmm; | |
74 | else if (imax == 2) H = 2.0 + (B - R) / cmm; | |
75 | else /*if (imax == 3)*/ H = 4.0 + (R - G) / cmm; | |
76 | if (H < 0) H += 6.0; | |
77 | } | |
78 | *h = (H * 60.0); | |
79 | *s = S; | |
80 | *v = V; | |
81 | } |