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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
24 #ifndef _SG_COLORS_HXX
25 #define _SG_COLORS_HXX 1
30 const float system_gamma = 2.0/1.7;
33 const float system_gamma = 2.5;
36 // simple architecture independant gamma correction function.
37 inline void gamma_correct_rgb(float *color,
38 float reff = 2.5, float system = system_gamma)
43 float tmp = reff/system;
44 color[0] = pow(color[0], tmp);
45 color[1] = pow(color[1], tmp);
46 color[2] = pow(color[2], tmp);
49 inline void gamma_correct_c(float *color,
50 float reff = 2.5, float system = system_gamma)
55 *color = pow(*color, reff/system);
58 inline void gamma_restore_rgb(float *color,
59 float reff = 2.5, float system = system_gamma)
64 float tmp = system/reff;
65 color[0] = pow(color[0], tmp);
66 color[1] = pow(color[1], tmp);
67 color[2] = pow(color[2], tmp);
70 inline void gamma_restore_c(float *color,
71 float reff = 2.5, float system = system_gamma)
76 *color = pow(*color, system/reff);
80 #endif // _SG_COLORS_HXX