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 Library General Public
21 // License along with this library; if not, write to the
22 // Free Software Foundation, Inc., 59 Temple Place - Suite 330,
23 // Boston, MA 02111-1307, USA.
28 #include <simgear/compiler.h>
40 // Set up sun rendering call backs
41 static int sgSunOrbPreDraw( ssgEntity *e ) {
42 /* cout << endl << "Sun orb pre draw" << endl << "----------------"
45 ssgLeaf *f = (ssgLeaf *)e;
46 if ( f -> hasState () ) f->getState()->apply() ;
48 glPushAttrib( GL_DEPTH_BUFFER_BIT | GL_FOG_BIT );
49 // cout << "push error = " << glGetError() << endl;
51 glDisable( GL_DEPTH_TEST );
57 static int sgSunOrbPostDraw( ssgEntity *e ) {
58 /* cout << endl << "Sun orb post draw" << endl << "----------------"
62 // cout << "pop error = " << glGetError() << endl;
64 // glEnable( GL_DEPTH_TEST );
65 // glEnable( GL_FOG );
70 static int sgSunHaloPreDraw( ssgEntity *e ) {
71 /* cout << endl << "Sun halo pre draw" << endl << "----------------"
74 ssgLeaf *f = (ssgLeaf *)e;
75 if ( f -> hasState () ) f->getState()->apply() ;
77 glPushAttrib( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_FOG_BIT );
78 // cout << "push error = " << glGetError() << endl;
80 glDisable( GL_DEPTH_TEST );
82 glBlendFunc ( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA ) ;
87 static int sgSunHaloPostDraw( ssgEntity *e ) {
88 /* cout << endl << "Sun halo post draw" << endl << "----------------"
92 // cout << "pop error = " << glGetError() << endl;
94 // glEnable( GL_DEPTH_TEST );
95 // glEnable( GL_FOG );
102 SGSun::SGSun( void ) {
107 SGSun::~SGSun( void ) {
112 static GLuint makeHalo( GLubyte *sun_texbuf, int width ) {
119 // create a texture id
120 #ifdef GL_VERSION_1_1
121 glGenTextures(1, &texid);
122 glBindTexture(GL_TEXTURE_2D, texid);
123 #elif GL_EXT_texture_object
124 glGenTexturesEXT(1, &texid);
125 glBindTextureEXT(GL_TEXTURE_2D, texid);
130 glPixelStorei( GL_UNPACK_ALIGNMENT, 4 );
131 glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
132 glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
133 glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE ) ;
135 // create the actual texture contents
136 texSize = width * width;
139 cout << "ouch ..." << endl;
145 radius = (double)(width / 2);
149 for ( i = 0; i < width; i++ ) {
150 for ( j = 0; j < width; j++ ) {
151 x = fabs((double)(i - (width / 2)));
152 y = fabs((double)(j - (width / 2)));
153 d = sqrt((x * x) + (y * y));
155 // t is 1.0 at center, 0.0 at edge
156 double t = 1.0 - (d / radius);
158 // inverse square looks nice
159 value = (int)((double) 0xff * (t*t));
172 /* glTexImage2D( GL_TEXTURE_2D,
177 GL_RGBA, GL_UNSIGNED_BYTE,
184 #define RGB 3 // 3 bytes of color info per pixel
185 #define RGBA 4 // 4 bytes of color+alpha info
186 void my_glWritePPMFile(const char *filename, GLubyte *buffer, int win_width, int win_height, int mode)
189 unsigned char *ibuffer;
191 int pixelSize = mode==GL_RGBA?4:3;
193 ibuffer = (unsigned char *) malloc(win_width*win_height*RGB);
195 fp = fopen(filename, "wb");
196 fprintf(fp, "P6\n# CREATOR: glReadPixel()\n%d %d\n%d\n",
197 win_width, win_height, UCHAR_MAX);
199 for (i = 0; i < win_height; i++) {
200 for (j = 0; j < win_width; j++) {
201 for (k = 0; k < RGB; k++) {
202 ibuffer[q++] = (unsigned char)
203 *(buffer + (pixelSize*((win_height-1-i)*win_width+j)+k));
208 // *(buffer + (pixelSize*((win_height-1-i)*win_width+j)+k));
210 fwrite(ibuffer, sizeof(unsigned char), RGB*win_width*win_height, fp);
214 printf("wrote file (%d x %d pixels, %d bytes)\n",
215 win_width, win_height, RGB*win_width*win_height);
220 // initialize the sun object and connect it into our scene graph root
221 ssgBranch * SGSun::build( SGPath path, double sun_size ) {
223 // set up the orb state
224 orb_state = new ssgSimpleState();
225 orb_state->setShadeModel( GL_SMOOTH );
226 orb_state->disable( GL_LIGHTING );
227 // orb_state->enable( GL_LIGHTING );
228 orb_state->disable( GL_CULL_FACE );
229 orb_state->disable( GL_TEXTURE_2D );
230 orb_state->enable( GL_COLOR_MATERIAL );
231 orb_state->setColourMaterial( GL_AMBIENT_AND_DIFFUSE );
232 orb_state->setMaterial( GL_EMISSION, 0, 0, 0, 1 );
233 orb_state->setMaterial( GL_SPECULAR, 0, 0, 0, 1 );
234 orb_state->disable( GL_BLEND );
235 orb_state->disable( GL_ALPHA_TEST );
237 cl = new ssgColourArray( 1 );
239 sgSetVec4( color, 1.0, 1.0, 1.0, 1.0 );
242 ssgBranch *orb = ssgMakeSphere( orb_state, cl, sun_size, 10, 10,
243 sgSunOrbPreDraw, sgSunOrbPostDraw );
245 // force a repaint of the sun colors with arbitrary defaults
249 // sun_texbuf = new GLubyte[64*64*3];
250 // sun_texid = makeHalo( sun_texbuf, 64 );
251 // my_glWritePPMFile("sunhalo.ppm", sun_texbuf, 64, 64, RGB);
253 // set up the halo state
254 path.append( "halo.rgba" );
255 halo_state = new ssgSimpleState();
256 halo_state->setTexture( (char *)path.c_str() );
257 halo_state->enable( GL_TEXTURE_2D );
258 halo_state->disable( GL_LIGHTING );
259 // halo_state->enable( GL_LIGHTING );
260 halo_state->setShadeModel( GL_SMOOTH );
261 halo_state->disable( GL_CULL_FACE );
262 halo_state->enable( GL_COLOR_MATERIAL );
263 halo_state->setColourMaterial( GL_AMBIENT_AND_DIFFUSE );
264 halo_state->setMaterial( GL_EMISSION, 0, 0, 0, 1 );
265 halo_state->setMaterial( GL_SPECULAR, 0, 0, 0, 1 );
266 halo_state->enable( GL_ALPHA_TEST );
267 halo_state->setAlphaClamp(0.01);
268 halo_state->enable ( GL_BLEND ) ;
270 // Build ssg structure
271 double size = sun_size * 10.0;
273 halo_vl = new ssgVertexArray;
274 sgSetVec3( v3, -size, 0.0, -size );
276 sgSetVec3( v3, size, 0.0, -size );
278 sgSetVec3( v3, -size, 0.0, size );
280 sgSetVec3( v3, size, 0.0, size );
284 halo_tl = new ssgTexCoordArray;
285 sgSetVec2( v2, 0.0f, 0.0f );
287 sgSetVec2( v2, 1.0, 0.0 );
289 sgSetVec2( v2, 0.0, 1.0 );
291 sgSetVec2( v2, 1.0, 1.0 );
295 new ssgVtxTable ( GL_TRIANGLE_STRIP, halo_vl, NULL, halo_tl, cl );
296 halo->setState( halo_state );
298 // build the ssg scene graph sub tree for the sky and connected
299 // into the provide scene graph branch
300 sun_transform = new ssgTransform;
302 halo->setCallback( SSG_CALLBACK_PREDRAW, sgSunHaloPreDraw );
303 halo->setCallback( SSG_CALLBACK_POSTDRAW, sgSunHaloPostDraw );
304 sun_transform->addKid( halo );
305 sun_transform->addKid( orb );
307 return sun_transform;
311 // repaint the sun colors based on current value of sun_angle in
312 // degrees relative to verticle
313 // 0 degrees = high noon
314 // 90 degrees = sun rise/set
315 // 180 degrees = darkest midnight
316 bool SGSun::repaint( double sun_angle ) {
317 if ( sun_angle * SGD_RADIANS_TO_DEGREES < 100 ) {
318 // else sun is well below horizon (so no point in repainting it)
320 // x_10 = sun_angle^10
321 double x_10 = sun_angle * sun_angle * sun_angle * sun_angle * sun_angle
322 * sun_angle * sun_angle * sun_angle * sun_angle * sun_angle;
324 float ambient = (float)(0.4 * pow (1.1, - x_10 / 30.0));
325 if (ambient < 0.3) { ambient = 0.3; }
326 if (ambient > 1.0) { ambient = 1.0; }
330 (ambient * 6.0) - 1.0, // minimum value = 0.8
331 (ambient * 11.0) - 3.0, // minimum value = 0.3
332 (ambient * 12.0) - 3.6, // minimum value = 0.0
335 // temp test, forces the color to always be white
336 // sgSetVec4( color, 1.0, 1.0, 1.0, 1.0 );
338 if (color[0] > 1.0) color[0] = 1.0;
339 if (color[1] > 1.0) color[1] = 1.0;
340 if (color[2] > 1.0) color[2] = 1.0;
342 // cout << "color = " << color[0] << " " << color[1] << " "
343 // << color[2] << endl;
347 sgCopyVec4( ptr, color );
354 // reposition the sun at the specified right ascension and
355 // declination, offset by our current position (p) so that it appears
356 // fixed at a great distance from the viewer. Also add in an optional
357 // rotation (i.e. for the current time of day.)
358 bool SGSun::reposition( sgVec3 p, double angle,
359 double rightAscension, double declination,
362 sgMat4 T1, T2, GST, RA, DEC;
366 sgMakeTransMat4( T1, p );
368 sgSetVec3( axis, 0.0, 0.0, -1.0 );
369 sgMakeRotMat4( GST, angle, axis );
371 // xglRotatef( ((SGD_RADIANS_TO_DEGREES * rightAscension)- 90.0),
373 sgSetVec3( axis, 0.0, 0.0, 1.0 );
374 sgMakeRotMat4( RA, (rightAscension * SGD_RADIANS_TO_DEGREES) - 90.0, axis );
376 // xglRotatef((SGD_RADIANS_TO_DEGREES * declination), 1.0, 0.0, 0.0);
377 sgSetVec3( axis, 1.0, 0.0, 0.0 );
378 sgMakeRotMat4( DEC, declination * SGD_RADIANS_TO_DEGREES, axis );
380 // xglTranslatef(0,sun_dist);
381 sgSetVec3( v, 0.0, sun_dist, 0.0 );
382 sgMakeTransMat4( T2, v );
385 sgCopyMat4( TRANSFORM, T1 );
386 sgPreMultMat4( TRANSFORM, GST );
387 sgPreMultMat4( TRANSFORM, RA );
388 sgPreMultMat4( TRANSFORM, DEC );
389 sgPreMultMat4( TRANSFORM, T2 );
392 sgSetCoord( &skypos, TRANSFORM );
394 sun_transform->setTransform( &skypos );