2 // light.cxx -- lighting routines
4 // Written by Curtis Olson, started April 1998.
6 // Copyright (C) 1998 Curtis L. Olson - curt@me.umn.edu
8 // This program is free software; you can redistribute it and/or
9 // modify it under the terms of the GNU General Public License as
10 // published by the Free Software Foundation; either version 2 of the
11 // License, or (at your option) any later version.
13 // This program is distributed in the hope that it will be useful, but
14 // WITHOUT ANY WARRANTY; without even the implied warranty of
15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 // General Public License for more details.
18 // You should have received a copy of the GNU General Public License
19 // along with this program; if not, write to the Free Software
20 // Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
35 #include <simgear/compiler.h>
37 #ifdef SG_MATH_EXCEPTION_CLASH
38 # define exception c_exception
41 #ifdef SG_HAVE_STD_INCLUDES
50 #include <simgear/constants.h>
51 #include <simgear/debug/logstream.hxx>
52 #include <simgear/math/interpolater.hxx>
53 #include <simgear/math/polar3d.hxx>
54 #include <simgear/misc/sg_path.hxx>
55 #include <simgear/scene/sky/sky.hxx>
56 #include <simgear/screen/colors.hxx>
58 #include <Main/main.hxx>
59 #include <Main/globals.hxx>
60 #include <Main/fg_props.hxx>
61 #include <Main/viewer.hxx>
69 : _ambient_tbl( NULL ),
71 _specular_tbl( NULL ),
74 _prev_sun_angle(-9999.0),
89 // initialize lighting tables
90 void FGLight::init () {
91 SG_LOG( SG_EVENT, SG_INFO,
92 "Initializing Lighting interpolation tables." );
94 // build the path names of the lookup tables
95 SGPath path( globals->get_fg_root() );
97 // initialize ambient, diffuse and specular tables
98 SGPath ambient_path = path;
99 ambient_path.append( "Lighting/ambient" );
100 _ambient_tbl = new SGInterpTable( ambient_path.str() );
102 SGPath diffuse_path = path;
103 diffuse_path.append( "Lighting/diffuse" );
104 _diffuse_tbl = new SGInterpTable( diffuse_path.str() );
106 SGPath specular_path = path;
107 specular_path.append( "Lighting/specular" );
108 _specular_tbl = new SGInterpTable( specular_path.str() );
110 // initialize sky table
111 SGPath sky_path = path;
112 sky_path.append( "Lighting/sky" );
113 _sky_tbl = new SGInterpTable( sky_path.str() );
117 void FGLight::reinit () {
118 _prev_sun_angle = -9999.0;
123 delete _specular_tbl;
132 update_adj_fog_color();
135 void FGLight::bind () {
138 void FGLight::unbind () {
142 // update lighting parameters based on current sun position
143 void FGLight::update( double dt ) {
146 if (_dt_total >= 0.5) {
152 update_adj_fog_color();
154 if (_prev_sun_angle != _sun_angle) {
155 _prev_sun_angle = _sun_angle;
160 void FGLight::update_sky_color () {
161 // if the 4th field is 0.0, this specifies a direction ...
162 const GLfloat white[4] = { 1.0, 1.0, 1.0, 1.0 };
163 const GLfloat base_sky_color[4] = { 0.39, 0.50, 0.74, 1.0 };
164 const GLfloat base_fog_color[4] = { 0.84, 0.87, 1.0, 1.0 };
166 SG_LOG( SG_EVENT, SG_INFO, "Updating light parameters." );
168 // calculate lighting parameters based on sun's relative angle to
171 float deg = _sun_angle * SGD_RADIANS_TO_DEGREES;
172 SG_LOG( SG_EVENT, SG_INFO, " Sun angle = " << deg );
174 float ambient = _ambient_tbl->interpolate( deg );
175 float diffuse = _diffuse_tbl->interpolate( deg );
176 float specular = _specular_tbl->interpolate( deg );
177 float sky_brightness = _sky_tbl->interpolate( deg );
179 SG_LOG( SG_EVENT, SG_INFO,
180 " ambient = " << ambient << " diffuse = " << diffuse
181 << " specular = " << specular << " sky = " << sky_brightness );
183 // sky_brightness = 0.15; // used to force a dark sky (when testing)
185 // if ( ambient < 0.02 ) { ambient = 0.02; }
186 // if ( diffuse < 0.0 ) { diffuse = 0.0; }
187 // if ( sky_brightness < 0.1 ) { sky_brightness = 0.1; }
190 _sky_color[0] = base_sky_color[0] * sky_brightness;
191 _sky_color[1] = base_sky_color[1] * sky_brightness;
192 _sky_color[2] = base_sky_color[2] * sky_brightness;
193 _sky_color[3] = base_sky_color[3];
194 gamma_correct_rgb( _sky_color );
196 // set cloud and fog color
197 _cloud_color[0] = _fog_color[0] = base_fog_color[0] * sky_brightness;
198 _cloud_color[1] = _fog_color[1] = base_fog_color[1] * sky_brightness;
199 _cloud_color[2] = _fog_color[2] = base_fog_color[2] * sky_brightness;
200 _cloud_color[3] = _fog_color[3] = base_fog_color[3];
201 gamma_correct_rgb( _fog_color );
203 // adjust the cloud colors for sunrise/sunset effects (darken them)
204 if (_sun_angle > 1.0) {
205 float sun2 = sqrt(_sun_angle);
206 _cloud_color[0] /= sun2;
207 _cloud_color[1] /= sun2;
208 _cloud_color[2] /= sun2;
210 gamma_correct_rgb( _cloud_color );
212 float *sun_color = thesky->get_sun_color();
214 _scene_ambient[0] = ((sun_color[0]*0.25 + _cloud_color[0]*0.75) + ambient) / 2;
215 _scene_ambient[1] = ((sun_color[1]*0.25 + _cloud_color[1]*0.75) + ambient) / 2;
216 _scene_ambient[2] = ((sun_color[2]*0.25 + _cloud_color[2]*0.75) + ambient) / 2;
217 _scene_ambient[3] = 1.0;
219 _scene_diffuse[0] = (sun_color[0]*0.25 + _fog_color[0]*0.75) * diffuse;
220 _scene_diffuse[1] = (sun_color[1]*0.25 + _fog_color[1]*0.75) * diffuse;
221 _scene_diffuse[2] = (sun_color[2]*0.25 + _fog_color[2]*0.75) * diffuse;
222 _scene_diffuse[3] = 1.0;
224 _scene_specular[0] = sun_color[0] * specular;
225 _scene_specular[1] = sun_color[1] * specular;
226 _scene_specular[2] = sun_color[2] * specular;
227 _scene_specular[3] = 1.0;
231 // calculate fog color adjusted for sunrise/sunset effects
232 void FGLight::update_adj_fog_color () {
234 double heading = globals->get_current_view()->getHeading_deg()
235 * SGD_DEGREES_TO_RADIANS;
236 double heading_offset = globals->get_current_view()->getHeadingOffset_deg()
237 * SGD_DEGREES_TO_RADIANS;
239 SG_LOG( SG_EVENT, SG_DEBUG, "Updating adjusted fog parameters." );
241 // set fog color (we'll try to match the sunset color in the
242 // direction we are looking
244 // Do some sanity checking ...
245 if ( _sun_rotation < -2.0 * SGD_2PI || _sun_rotation > 2.0 * SGD_2PI ) {
246 SG_LOG( SG_EVENT, SG_ALERT, "Sun rotation bad = " << _sun_rotation );
250 if ( heading < -2.0 * SGD_2PI || heading > 2.0 * SGD_2PI ) {
251 SG_LOG( SG_EVENT, SG_ALERT, "Heading rotation bad = " << heading );
255 if ( heading_offset < -2.0 * SGD_2PI || heading_offset > 2.0 * SGD_2PI ) {
256 SG_LOG( SG_EVENT, SG_ALERT, "Heading offset bad = " << heading_offset );
262 // first determine the difference between our view angle and local
263 // direction to the sun
264 rotation = -(_sun_rotation + SGD_PI) - heading + heading_offset;
265 while ( rotation < 0 ) {
268 while ( rotation > SGD_2PI ) {
272 // revert to unmodified values before usign them.
274 float *sun_color = thesky->get_sun_color();
276 gamma_restore_rgb( _fog_color );
278 // Calculate the fog color in the direction of the sun for
279 // sunrise/sunset effects.
281 float s_red = (_fog_color[0] + 2 * sun_color[0]*sun_color[0]) / 3;
282 float s_green = (_fog_color[1] + 2 * sun_color[1]*sun_color[1]) / 3;
283 float s_blue = (_fog_color[2] + 2 * sun_color[2]) / 3;
285 // interpolate beween the sunrise/sunset color and the color
286 // at the opposite direction of this effect. Take in account
287 // the current visibility.
289 float av = thesky->get_visibility();
293 float avf = 0.87 - (45000 - av) / 83333.33;
294 float sif = 0.5 - cos(_sun_angle*2)/2;
296 float rf1 = fabs((rotation - SGD_PI) / SGD_PI); // 0.0 .. 1.0
297 float rf2 = avf * pow(rf1 * rf1, 1/sif);
298 float rf3 = 0.94 - rf2;
300 _adj_fog_color[0] = rf3 * _fog_color[0] + rf2 * s_red;
301 _adj_fog_color[1] = rf3 * _fog_color[1] + rf2 * s_green;
302 _adj_fog_color[2] = rf3 * _fog_color[2] + rf2 * s_blue;
303 gamma_correct_rgb( _adj_fog_color );
305 // make sure the colors have their original value before they are being
306 // used by the rest of the program.
308 gamma_correct_rgb( _fog_color );