1 // oursun.hxx -- model earth's sun
3 // Written by Durk Talsma. Originally started October 1997, for distribution
4 // with the FlightGear project. Version 2 was written in August and
5 // September 1998. This code is based upon algorithms and data kindly
6 // provided by Mr. Paul Schlyter. (pausch@saaf.se).
8 // Separated out rendering pieces and converted to ssg by Curt Olson,
10 // This library is free software; you can redistribute it and/or
11 // modify it under the terms of the GNU Library General Public
12 // License as published by the Free Software Foundation; either
13 // version 2 of the License, or (at your option) any later version.
15 // This library is distributed in the hope that it will be useful,
16 // but WITHOUT ANY WARRANTY; without even the implied warranty of
17 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 // Library General Public License for more details.
20 // You should have received a copy of the GNU General Public License
21 // along with this program; if not, write to the Free Software
22 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
28 # include <simgear_config.h>
31 #include <simgear/compiler.h>
39 // define the following to enable a cheesy lens flare effect for the sun
40 // #define FG_TEST_CHEESY_LENS_FLARE
42 #ifdef FG_TEST_CHEESY_LENS_FLARE
43 # include <plib/ssgaLensFlare.h>
46 #include <simgear/screen/colors.hxx>
51 static double sun_exp2_punch_through;
53 // Set up sun rendering call backs
54 static int sgSunOrbPreDraw( ssgEntity *e ) {
55 /* cout << endl << "Sun orb pre draw" << endl << "----------------"
58 ssgLeaf *f = (ssgLeaf *)e;
59 if ( f -> hasState () ) f->getState()->apply() ;
61 glPushAttrib( GL_DEPTH_BUFFER_BIT | GL_FOG_BIT );
62 // cout << "push error = " << glGetError() << endl;
64 glDisable( GL_DEPTH_TEST );
70 static int sgSunOrbPostDraw( ssgEntity *e ) {
71 /* cout << endl << "Sun orb post draw" << endl << "----------------"
75 // cout << "pop error = " << glGetError() << endl;
80 static int sgSunHaloPreDraw( ssgEntity *e ) {
81 /* cout << endl << "Sun halo pre draw" << endl << "----------------"
84 ssgLeaf *f = (ssgLeaf *)e;
85 if ( f -> hasState () ) f->getState()->apply() ;
87 glPushAttrib( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_FOG_BIT );
88 // cout << "push error = " << glGetError() << endl;
90 glDisable( GL_DEPTH_TEST );
91 // glDisable( GL_FOG );
92 glFogf (GL_FOG_DENSITY, sun_exp2_punch_through);
93 glBlendFunc ( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA ) ;
98 static int sgSunHaloPostDraw( ssgEntity *e ) {
99 /* cout << endl << "Sun halo post draw" << endl << "----------------"
103 // cout << "pop error = " << glGetError() << endl;
110 SGSun::SGSun( void ) {
111 prev_sun_angle = -9999.0;
112 visibility = -9999.0;
117 SGSun::~SGSun( void ) {
122 // this might be nice to keep, just as an example of how to generate a
123 // texture on the fly ...
124 static GLuint makeHalo( GLubyte *sun_texbuf, int width ) {
131 // create a texture id
132 #ifdef GL_VERSION_1_1
133 glGenTextures(1, &texid);
134 glBindTexture(GL_TEXTURE_2D, texid);
135 #elif GL_EXT_texture_object
136 glGenTexturesEXT(1, &texid);
137 glBindTextureEXT(GL_TEXTURE_2D, texid);
142 glPixelStorei( GL_UNPACK_ALIGNMENT, 4 );
143 glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
144 glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
145 glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE ) ;
147 // create the actual texture contents
148 texSize = width * width;
151 SG_LOG( SG_EVENT, SG_ALERT,
152 "Could not allocate memroy for the sun texture");
158 radius = (double)(width / 2);
162 for ( i = 0; i < width; i++ ) {
163 for ( j = 0; j < width; j++ ) {
164 x = fabs((double)(i - (width / 2)));
165 y = fabs((double)(j - (width / 2)));
166 d = sqrt((x * x) + (y * y));
168 // t is 1.0 at center, 0.0 at edge
169 double t = 1.0 - (d / radius);
171 // inverse square looks nice
172 value = (int)((double) 0xff * (t*t));
185 /* glTexImage2D( GL_TEXTURE_2D,
190 GL_RGBA, GL_UNSIGNED_BYTE,
197 #define RGB 3 // 3 bytes of color info per pixel
198 #define RGBA 4 // 4 bytes of color+alpha info
199 void my_glWritePPMFile(const char *filename, GLubyte *buffer, int win_width, int win_height, int mode)
202 unsigned char *ibuffer;
204 int pixelSize = mode==GL_RGBA?4:3;
206 ibuffer = (unsigned char *) malloc(win_width*win_height*RGB);
208 fp = fopen(filename, "wb");
209 fprintf(fp, "P6\n# CREATOR: glReadPixel()\n%d %d\n%d\n",
210 win_width, win_height, UCHAR_MAX);
212 for (i = 0; i < win_height; i++) {
213 for (j = 0; j < win_width; j++) {
214 for (k = 0; k < RGB; k++) {
215 ibuffer[q++] = (unsigned char)
216 *(buffer + (pixelSize*((win_height-1-i)*win_width+j)+k));
221 // *(buffer + (pixelSize*((win_height-1-i)*win_width+j)+k));
223 fwrite(ibuffer, sizeof(unsigned char), RGB*win_width*win_height, fp);
227 printf("wrote file (%d x %d pixels, %d bytes)\n",
228 win_width, win_height, RGB*win_width*win_height);
233 // initialize the sun object and connect it into our scene graph root
234 ssgBranch * SGSun::build( SGPath path, double sun_size ) {
236 // set up the orb state
237 orb_state = new ssgSimpleState();
238 orb_state->setShadeModel( GL_SMOOTH );
239 orb_state->disable( GL_LIGHTING );
240 // orb_state->enable( GL_LIGHTING );
241 orb_state->disable( GL_CULL_FACE );
242 orb_state->disable( GL_TEXTURE_2D );
243 orb_state->enable( GL_COLOR_MATERIAL );
244 orb_state->setColourMaterial( GL_AMBIENT_AND_DIFFUSE );
245 orb_state->setMaterial( GL_EMISSION, 0, 0, 0, 1 );
246 orb_state->setMaterial( GL_SPECULAR, 0, 0, 0, 1 );
247 orb_state->disable( GL_BLEND );
248 orb_state->disable( GL_ALPHA_TEST );
250 cl = new ssgColourArray( 1 );
252 sgSetVec4( color, 1.0, 1.0, 1.0, 1.0 );
255 ssgBranch *orb = ssgMakeSphere( orb_state, cl, sun_size, 10, 10,
256 sgSunOrbPreDraw, sgSunOrbPostDraw );
258 // force a repaint of the sun colors with arbitrary defaults
262 // sun_texbuf = new GLubyte[64*64*3];
263 // sun_texid = makeHalo( sun_texbuf, 64 );
264 // my_glWritePPMFile("sunhalo.ppm", sun_texbuf, 64, 64, RGB);
266 // set up the halo state
267 path.append( "halo.rgba" );
268 halo_state = new ssgSimpleState();
269 halo_state->setTexture( (char *)path.c_str() );
270 halo_state->enable( GL_TEXTURE_2D );
271 halo_state->disable( GL_LIGHTING );
272 // halo_state->enable( GL_LIGHTING );
273 halo_state->setShadeModel( GL_SMOOTH );
274 halo_state->disable( GL_CULL_FACE );
275 halo_state->enable( GL_COLOR_MATERIAL );
276 halo_state->setColourMaterial( GL_AMBIENT_AND_DIFFUSE );
277 halo_state->setMaterial( GL_EMISSION, 0, 0, 0, 1 );
278 halo_state->setMaterial( GL_SPECULAR, 0, 0, 0, 1 );
279 halo_state->enable( GL_ALPHA_TEST );
280 halo_state->setAlphaClamp(0.01);
281 halo_state->enable ( GL_BLEND ) ;
283 // Build ssg structure
284 double size = sun_size * 10.0;
286 halo_vl = new ssgVertexArray;
287 sgSetVec3( v3, -size, 0.0, -size );
289 sgSetVec3( v3, size, 0.0, -size );
291 sgSetVec3( v3, -size, 0.0, size );
293 sgSetVec3( v3, size, 0.0, size );
297 halo_tl = new ssgTexCoordArray;
298 sgSetVec2( v2, 0.0f, 0.0f );
300 sgSetVec2( v2, 1.0, 0.0 );
302 sgSetVec2( v2, 0.0, 1.0 );
304 sgSetVec2( v2, 1.0, 1.0 );
308 new ssgVtxTable ( GL_TRIANGLE_STRIP, halo_vl, NULL, halo_tl, cl );
309 halo->setState( halo_state );
311 // build the ssg scene graph sub tree for the sky and connected
312 // into the provide scene graph branch
313 sun_transform = new ssgTransform;
315 halo->setCallback( SSG_CALLBACK_PREDRAW, sgSunHaloPreDraw );
316 halo->setCallback( SSG_CALLBACK_POSTDRAW, sgSunHaloPostDraw );
317 sun_transform->addKid( halo );
318 sun_transform->addKid( orb );
320 #ifdef FG_TEST_CHEESY_LENS_FLARE
322 sun_transform->addKid( new ssgaLensFlare );
325 return sun_transform;
329 // repaint the sun colors based on current value of sun_angle in
330 // degrees relative to verticle
331 // 0 degrees = high noon
332 // 90 degrees = sun rise/set
333 // 180 degrees = darkest midnight
334 bool SGSun::repaint( double sun_angle, double new_visibility ) {
335 if ( visibility != new_visibility ) {
336 visibility = new_visibility;
338 static double sqrt_m_log01 = sqrt( -log( 0.01 ) );
339 sun_exp2_punch_through = sqrt_m_log01 / (visibility * 15);
342 if (prev_sun_angle != sun_angle) {
343 prev_sun_angle = sun_angle;
345 double nv = (new_visibility > 5000.0) ? new_visibility : 5000.0;
346 double vis_factor = 10000.0 / (nv - 5000.0);
347 if ( vis_factor < 0.25 ) {
349 } else if ( vis_factor > 1.0) {
353 float sun_factor = 4 * (cos(sun_angle) + cos(sun_angle)/2) * vis_factor;
355 if (sun_factor > 1) sun_factor = 1.0;
356 if (sun_factor < -1) sun_factor = -1.0;
357 sun_factor = (sun_factor/2) + 0.5;
360 color[1] = sqrt(sun_factor);
361 color[0] = sqrt(color[1]);
362 color[2] = sun_factor * sun_factor;
363 color[2] *= color[2];
366 gamma_correct_rgb( color );
368 // cout << "color = " << color[0] << " " << color[1] << " "
369 // << color[2] << endl;
373 sgCopyVec4( ptr, color );
380 // reposition the sun at the specified right ascension and
381 // declination, offset by our current position (p) so that it appears
382 // fixed at a great distance from the viewer. Also add in an optional
383 // rotation (i.e. for the current time of day.)
384 bool SGSun::reposition( sgVec3 p, double angle,
385 double rightAscension, double declination,
388 sgMat4 T1, T2, GST, RA, DEC;
392 sgMakeTransMat4( T1, p );
394 sgSetVec3( axis, 0.0, 0.0, -1.0 );
395 sgMakeRotMat4( GST, angle, axis );
397 // xglRotatef( ((SGD_RADIANS_TO_DEGREES * rightAscension)- 90.0),
399 sgSetVec3( axis, 0.0, 0.0, 1.0 );
400 sgMakeRotMat4( RA, (rightAscension * SGD_RADIANS_TO_DEGREES) - 90.0, axis );
402 // xglRotatef((SGD_RADIANS_TO_DEGREES * declination), 1.0, 0.0, 0.0);
403 sgSetVec3( axis, 1.0, 0.0, 0.0 );
404 sgMakeRotMat4( DEC, declination * SGD_RADIANS_TO_DEGREES, axis );
406 // xglTranslatef(0,sun_dist);
407 sgSetVec3( v, 0.0, sun_dist, 0.0 );
408 sgMakeTransMat4( T2, v );
411 sgCopyMat4( TRANSFORM, T1 );
412 sgPreMultMat4( TRANSFORM, GST );
413 sgPreMultMat4( TRANSFORM, RA );
414 sgPreMultMat4( TRANSFORM, DEC );
415 sgPreMultMat4( TRANSFORM, T2 );
418 sgSetCoord( &skypos, TRANSFORM );
420 sun_transform->setTransform( &skypos );