projects / screensavers / blame
| Commit | Line | Data |
|---|---|---|
| 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 | } |