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