3 // -- This header file contains color related functions
5 // Copyright (C) 2003 FlightGear Flight Simulator
7 // This program is free software; you can redistribute it and/or
8 // modify it under the terms of the GNU General Public License as
9 // published by the Free Software Foundation; either version 2 of the
10 // License, or (at your option) any later version.
12 // This program is distributed in the hope that it will be useful, but
13 // WITHOUT ANY WARRANTY; without even the implied warranty of
14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 // General Public License for more details.
17 // You should have received a copy of the GNU General Public License
18 // along with this program; if not, write to the Free Software
19 // Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 #ifndef _SG_COLORS_HXX
25 #define _SG_COLORS_HXX 1
29 #if defined( macintosh )
30 const float system_gamma = 1.4;
33 const float system_gamma = 1.7;
36 const float system_gamma = 2.5;
39 // simple architecture independant gamma correction function.
40 inline void gamma_correct_rgb(float *color,
41 float reff = 2.5, float system = system_gamma)
46 float tmp = reff/system;
47 color[0] = pow(color[0], tmp);
48 color[1] = pow(color[1], tmp);
49 color[2] = pow(color[2], tmp);
51 if ( color[0] < 0.0 ) { color[0] = 0.0; }
52 if ( color[1] < 0.0 ) { color[1] = 0.0; }
53 if ( color[2] < 0.0 ) { color[2] = 0.0; }
54 if ( color[0] > 1.0 ) { color[0] = 1.0; }
55 if ( color[1] > 1.0 ) { color[1] = 1.0; }
56 if ( color[2] > 1.0 ) { color[2] = 1.0; }
59 inline void gamma_correct_c(float *color,
60 float reff = 2.5, float system = system_gamma)
65 *color = pow(*color, reff/system);
66 if ( *color < 0.0 ) { *color = 0.0; }
67 if ( *color > 1.0 ) { *color = 1.0; }
70 inline void gamma_restore_rgb(float *color,
71 float reff = 2.5, float system = system_gamma)
76 float tmp = system/reff;
77 color[0] = pow(color[0], tmp);
78 color[1] = pow(color[1], tmp);
79 color[2] = pow(color[2], tmp);
81 if ( color[0] < 0.0 ) { color[0] = 0.0; }
82 if ( color[1] < 0.0 ) { color[1] = 0.0; }
83 if ( color[2] < 0.0 ) { color[2] = 0.0; }
84 if ( color[0] > 1.0 ) { color[0] = 1.0; }
85 if ( color[1] > 1.0 ) { color[1] = 1.0; }
86 if ( color[2] > 1.0 ) { color[2] = 1.0; }
89 inline void gamma_restore_c(float *color,
90 float reff = 2.5, float system = system_gamma)
95 *color = pow(*color, system/reff);
96 if ( *color < 0.0 ) { *color = 0.0; }
97 if ( *color > 1.0 ) { *color = 1.0; }
101 #endif // _SG_COLORS_HXX