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 program is free software; you can redistribute it and/or
11 // modify it under the terms of the GNU General Public License as
12 // published by the Free Software Foundation; either version 2 of the
13 // License, or (at your option) any later version.
15 // This program is distributed in the hope that it will be useful, but
16 // WITHOUT ANY WARRANTY; without even the implied warranty of
17 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 // 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., 675 Mass Ave, Cambridge, MA 02139, USA.
41 // Set up sun rendering call backs
42 static int sgSunOrbPreDraw( ssgEntity *e ) {
43 /* cout << endl << "Sun orb pre draw" << endl << "----------------"
45 glDisable( GL_DEPTH_TEST );
51 static int sgSunOrbPostDraw( ssgEntity *e ) {
52 /* cout << endl << "Sun orb post draw" << endl << "----------------"
54 glEnable( GL_DEPTH_TEST );
60 static int sgSunHaloPreDraw( ssgEntity *e ) {
61 /* cout << endl << "Sun halo pre draw" << endl << "----------------"
63 glDisable( GL_DEPTH_TEST );
65 glBlendFunc ( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA ) ;
70 static int sgSunHaloPostDraw( ssgEntity *e ) {
71 /* cout << endl << "Sun halo post draw" << endl << "----------------"
73 glEnable( GL_DEPTH_TEST );
81 SGSun::SGSun( void ) {
86 SGSun::~SGSun( void ) {
91 static GLuint makeHalo( GLubyte *sun_texbuf, int width ) {
98 // create a texture id
100 glGenTextures(1, &texid);
101 glBindTexture(GL_TEXTURE_2D, texid);
102 #elif GL_EXT_texture_object
103 glGenTexturesEXT(1, &texid);
104 glBindTextureEXT(GL_TEXTURE_2D, texid);
109 glPixelStorei( GL_UNPACK_ALIGNMENT, 4 );
110 glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
111 glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
112 glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE ) ;
114 // create the actual texture contents
115 texSize = width * width;
118 cout << "ouch ..." << endl;
124 radius = (double)(width / 2);
128 for ( i = 0; i < width; i++ ) {
129 for ( j = 0; j < width; j++ ) {
130 x = fabs((double)(i - (width / 2)));
131 y = fabs((double)(j - (width / 2)));
132 d = sqrt((x * x) + (y * y));
134 // t is 1.0 at center, 0.0 at edge
135 double t = 1.0 - (d / radius);
137 // inverse square looks nice
138 value = (int)((double) 0xff * (t*t));
151 /* glTexImage2D( GL_TEXTURE_2D,
156 GL_RGBA, GL_UNSIGNED_BYTE,
163 #define RGB 3 // 3 bytes of color info per pixel
164 #define RGBA 4 // 4 bytes of color+alpha info
165 void my_glWritePPMFile(const char *filename, GLubyte *buffer, int win_width, int win_height, int mode)
168 unsigned char *ibuffer;
170 int pixelSize = mode==GL_RGBA?4:3;
172 ibuffer = (unsigned char *) malloc(win_width*win_height*RGB);
174 fp = fopen(filename, "wb");
175 fprintf(fp, "P6\n# CREATOR: glReadPixel()\n%d %d\n%d\n",
176 win_width, win_height, UCHAR_MAX);
178 for (i = 0; i < win_height; i++) {
179 for (j = 0; j < win_width; j++) {
180 for (k = 0; k < RGB; k++) {
181 ibuffer[q++] = (unsigned char)
182 *(buffer + (pixelSize*((win_height-1-i)*win_width+j)+k));
187 // *(buffer + (pixelSize*((win_height-1-i)*win_width+j)+k));
189 fwrite(ibuffer, sizeof(unsigned char), RGB*win_width*win_height, fp);
193 printf("wrote file (%d x %d pixels, %d bytes)\n",
194 win_width, win_height, RGB*win_width*win_height);
199 // initialize the sun object and connect it into our scene graph root
200 ssgBranch * SGSun::build( FGPath path, double sun_size ) {
202 // set up the orb state
203 orb_state = new ssgSimpleState();
204 orb_state->setShadeModel( GL_SMOOTH );
205 orb_state->disable( GL_LIGHTING );
206 // orb_state->enable( GL_LIGHTING );
207 orb_state->disable( GL_CULL_FACE );
208 orb_state->disable( GL_TEXTURE_2D );
209 orb_state->enable( GL_COLOR_MATERIAL );
210 orb_state->setColourMaterial( GL_AMBIENT_AND_DIFFUSE );
211 orb_state->setMaterial( GL_EMISSION, 0, 0, 0, 1 );
212 orb_state->setMaterial( GL_SPECULAR, 0, 0, 0, 1 );
213 orb_state->disable( GL_BLEND );
214 orb_state->disable( GL_ALPHA_TEST );
216 cl = new ssgColourArray( 1 );
218 sgSetVec4( color, 1.0, 1.0, 1.0, 1.0 );
221 ssgBranch *orb = ssgMakeSphere( orb_state, cl, sun_size, 10, 10,
222 sgSunOrbPreDraw, sgSunOrbPostDraw );
224 // force a repaint of the sun colors with arbitrary defaults
228 // sun_texbuf = new GLubyte[64*64*3];
229 // sun_texid = makeHalo( sun_texbuf, 64 );
230 // my_glWritePPMFile("sunhalo.ppm", sun_texbuf, 64, 64, RGB);
232 // set up the halo state
233 path.append( "halo.rgba" );
234 halo_state = new ssgSimpleState();
235 halo_state->setTexture( (char *)path.c_str() );
236 halo_state->enable( GL_TEXTURE_2D );
237 halo_state->disable( GL_LIGHTING );
238 // halo_state->enable( GL_LIGHTING );
239 halo_state->setShadeModel( GL_SMOOTH );
240 halo_state->disable( GL_CULL_FACE );
241 halo_state->enable( GL_COLOR_MATERIAL );
242 halo_state->setColourMaterial( GL_AMBIENT_AND_DIFFUSE );
243 halo_state->setMaterial( GL_EMISSION, 0, 0, 0, 1 );
244 halo_state->setMaterial( GL_SPECULAR, 0, 0, 0, 1 );
245 halo_state->enable( GL_ALPHA_TEST );
246 halo_state->setAlphaClamp(0.01);
247 halo_state->enable ( GL_BLEND ) ;
249 // Build ssg structure
250 double size = sun_size * 10.0;
252 halo_vl = new ssgVertexArray;
253 sgSetVec3( v3, -size, 0.0, -size );
255 sgSetVec3( v3, size, 0.0, -size );
257 sgSetVec3( v3, -size, 0.0, size );
259 sgSetVec3( v3, size, 0.0, size );
263 halo_tl = new ssgTexCoordArray;
264 sgSetVec2( v2, 0.0f, 0.0f );
266 sgSetVec2( v2, 1.0, 0.0 );
268 sgSetVec2( v2, 0.0, 1.0 );
270 sgSetVec2( v2, 1.0, 1.0 );
274 new ssgVtxTable ( GL_TRIANGLE_STRIP, halo_vl, NULL, halo_tl, cl );
275 halo->setState( halo_state );
277 // build the ssg scene graph sub tree for the sky and connected
278 // into the provide scene graph branch
279 sun_transform = new ssgTransform;
281 halo->setCallback( SSG_CALLBACK_PREDRAW, sgSunHaloPreDraw );
282 halo->setCallback( SSG_CALLBACK_POSTDRAW, sgSunHaloPostDraw );
283 sun_transform->addKid( halo );
284 sun_transform->addKid( orb );
286 return sun_transform;
290 // repaint the sun colors based on current value of sun_angle in
291 // degrees relative to verticle
292 // 0 degrees = high noon
293 // 90 degrees = sun rise/set
294 // 180 degrees = darkest midnight
295 bool SGSun::repaint( double sun_angle ) {
296 if ( sun_angle * SGD_RADIANS_TO_DEGREES < 100 ) {
297 // else sun is well below horizon (so no point in repainting it)
299 // x_10 = sun_angle^10
300 double x_10 = sun_angle * sun_angle * sun_angle * sun_angle * sun_angle
301 * sun_angle * sun_angle * sun_angle * sun_angle * sun_angle;
303 float ambient = (float)(0.4 * pow (1.1, - x_10 / 30.0));
304 if (ambient < 0.3) { ambient = 0.3; }
305 if (ambient > 1.0) { ambient = 1.0; }
309 (ambient * 6.0) - 1.0, // minimum value = 0.8
310 (ambient * 11.0) - 3.0, // minimum value = 0.3
311 (ambient * 12.0) - 3.6, // minimum value = 0.0
314 // temp test, forces the color to always be white
315 // sgSetVec4( color, 1.0, 1.0, 1.0, 1.0 );
317 if (color[0] > 1.0) color[0] = 1.0;
318 if (color[1] > 1.0) color[1] = 1.0;
319 if (color[2] > 1.0) color[2] = 1.0;
321 // cout << "color = " << color[0] << " " << color[1] << " "
322 // << color[2] << endl;
326 sgCopyVec4( ptr, color );
333 // reposition the sun at the specified right ascension and
334 // declination, offset by our current position (p) so that it appears
335 // fixed at a great distance from the viewer. Also add in an optional
336 // rotation (i.e. for the current time of day.)
337 bool SGSun::reposition( sgVec3 p, double angle,
338 double rightAscension, double declination,
341 sgMat4 T1, T2, GST, RA, DEC;
345 sgMakeTransMat4( T1, p );
347 sgSetVec3( axis, 0.0, 0.0, -1.0 );
348 sgMakeRotMat4( GST, angle, axis );
350 // xglRotatef( ((SGD_RADIANS_TO_DEGREES * rightAscension)- 90.0),
352 sgSetVec3( axis, 0.0, 0.0, 1.0 );
353 sgMakeRotMat4( RA, (rightAscension * SGD_RADIANS_TO_DEGREES) - 90.0, axis );
355 // xglRotatef((SGD_RADIANS_TO_DEGREES * declination), 1.0, 0.0, 0.0);
356 sgSetVec3( axis, 1.0, 0.0, 0.0 );
357 sgMakeRotMat4( DEC, declination * SGD_RADIANS_TO_DEGREES, axis );
359 // xglTranslatef(0,sun_dist);
360 sgSetVec3( v, 0.0, sun_dist, 0.0 );
361 sgMakeTransMat4( T2, v );
364 sgCopyMat4( TRANSFORM, T1 );
365 sgPreMultMat4( TRANSFORM, GST );
366 sgPreMultMat4( TRANSFORM, RA );
367 sgPreMultMat4( TRANSFORM, DEC );
368 sgPreMultMat4( TRANSFORM, T2 );
371 sgSetCoord( &skypos, TRANSFORM );
373 sun_transform->setTransform( &skypos );