1 // moon.hxx -- model earth's moon
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>
36 #include <simgear/constants.h>
37 #include <simgear/screen/colors.hxx>
43 // Set up moon rendering call backs
44 static int sgMoonOrbPreDraw( ssgEntity *e ) {
45 /* cout << endl << "Moon orb pre draw" << endl << "----------------"
48 ssgLeaf *f = (ssgLeaf *)e;
49 if ( f -> hasState () ) f->getState()->apply() ;
51 glPushAttrib( GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT | GL_ENABLE_BIT );
52 // cout << "push error = " << glGetError() << endl;
54 glDisable( GL_DEPTH_TEST );
56 glBlendFunc ( GL_SRC_ALPHA, GL_ONE ) ;
62 static int sgMoonOrbPostDraw( ssgEntity *e ) {
63 /* cout << endl << "Moon orb post draw" << endl << "----------------"
66 // Some drivers don't properly reset glBendFunc with a
67 // glPopAttrib() so we reset it to the 'default' here.
68 glBlendFunc ( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA ) ;
71 // cout << "pop error = " << glGetError() << endl;
78 static int sgMoonHaloPreDraw( ssgEntity *e ) {
79 /* cout << endl << "Moon halo pre draw" << endl << "----------------"
82 ssgLeaf *f = (ssgLeaf *)e;
83 if ( f -> hasState () ) f->getState()->apply() ;
85 glPushAttrib( GL_DEPTH_BUFFER_BIT | GL_FOG_BIT | GL_COLOR_BUFFER_BIT);
86 // cout << "push error = " << glGetError() << endl;
88 glDisable( GL_DEPTH_TEST );
90 glBlendFunc ( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA ) ;
95 static int sgMoonHaloPostDraw( ssgEntity *e ) {
96 /* cout << endl << "Moon halo post draw" << endl << "----------------"
100 // cout << "pop error = " << glGetError() << endl;
108 SGMoon::SGMoon( void ) :
115 SGMoon::~SGMoon( void ) {
119 // build the moon object
120 ssgBranch * SGMoon::build( SGPath path, double moon_size ) {
122 // set up the orb state
123 path.append( "moon.rgba" );
124 orb_state = new ssgSimpleState();
125 orb_state->setTexture( (char *)path.c_str() );
126 orb_state->setShadeModel( GL_SMOOTH );
127 orb_state->enable( GL_LIGHTING );
128 orb_state->enable( GL_CULL_FACE );
129 orb_state->enable( GL_TEXTURE_2D );
130 orb_state->enable( GL_COLOR_MATERIAL );
131 orb_state->setColourMaterial( GL_DIFFUSE );
132 orb_state->setMaterial( GL_AMBIENT, 0, 0, 0, 1.0 );
133 orb_state->setMaterial( GL_EMISSION, 0.0, 0.0, 0.0, 1 );
134 orb_state->setMaterial( GL_SPECULAR, 0, 0, 0, 1 );
135 orb_state->enable( GL_BLEND );
136 orb_state->enable( GL_ALPHA_TEST );
137 orb_state->setAlphaClamp( 0.01 );
139 cl = new ssgColourArray( 1 );
141 sgSetVec4( color, 1.0, 1.0, 1.0, 1.0 );
144 ssgBranch *orb = ssgMakeSphere( orb_state, cl, moon_size, 15, 15,
145 sgMoonOrbPreDraw, sgMoonOrbPostDraw );
147 // force a repaint of the moon colors with arbitrary defaults
151 // moon_texbuf = new GLubyte[64*64*3];
152 // moon_texid = makeHalo( moon_texbuf, 64 );
153 // my_glWritePPMFile("moonhalo.ppm", moon_texbuf, 64, 64, RGB);
156 // set up the halo state
157 halo_state = new ssgSimpleState();
158 halo_state->setTexture( "halo.rgb" );
159 // halo_state->setTexture( moon_texid );
160 halo_state->enable( GL_TEXTURE_2D );
161 halo_state->disable( GL_LIGHTING );
162 halo_state->setShadeModel( GL_SMOOTH );
163 halo_state->disable( GL_CULL_FACE );
165 halo_state->disable( GL_COLOR_MATERIAL );
166 halo_state->setColourMaterial( GL_AMBIENT_AND_DIFFUSE );
167 halo_state->setMaterial ( GL_AMBIENT_AND_DIFFUSE, 1, 1, 1, 1 ) ;
168 halo_state->setMaterial ( GL_EMISSION, 0, 0, 0, 1 ) ;
169 halo_state->setMaterial ( GL_SPECULAR, 0, 0, 0, 1 ) ;
170 // halo_state -> setShininess ( 0 ) ;
171 halo_state->enable( GL_ALPHA_TEST );
172 halo_state->setAlphaClamp(0.01);
173 halo_state->enable ( GL_BLEND ) ;
176 // Build ssg structure
177 double size = moon_size * 10.0;
179 halo_vl = new ssgVertexArray;
180 sgSetVec3( v3, -size, 0.0, -size );
182 sgSetVec3( v3, size, 0.0, -size );
184 sgSetVec3( v3, -size, 0.0, size );
186 sgSetVec3( v3, size, 0.0, size );
190 halo_tl = new ssgTexCoordArray;
191 sgSetVec2( v2, 0.0f, 0.0f );
193 sgSetVec2( v2, 1.0, 0.0 );
195 sgSetVec2( v2, 0.0, 1.0 );
197 sgSetVec2( v2, 1.0, 1.0 );
201 new ssgVtxTable ( GL_TRIANGLE_STRIP, halo_vl, NULL, halo_tl, cl );
202 halo->setState( halo_state );
205 // build the ssg scene graph sub tree for the sky and connected
206 // into the provide scene graph branch
207 moon_transform = new ssgTransform;
209 // moon_transform->addKid( halo );
210 moon_transform->addKid( orb );
212 return moon_transform;
216 // repaint the moon colors based on current value of moon_angle in
217 // degrees relative to verticle
218 // 0 degrees = high noon
219 // 90 degrees = moon rise/set
220 // 180 degrees = darkest midnight
221 bool SGMoon::repaint( double moon_angle ) {
223 if (prev_moon_angle != moon_angle) {
224 prev_moon_angle = moon_angle;
226 float moon_factor = 4*cos(moon_angle);
228 if (moon_factor > 1) moon_factor = 1.0;
229 if (moon_factor < -1) moon_factor = -1.0;
230 moon_factor = moon_factor/2 + 0.5;
233 color[1] = sqrt(moon_factor);
234 color[0] = sqrt(color[1]);
235 color[2] = moon_factor * moon_factor;
236 color[2] *= color[2];
239 gamma_correct_rgb( color );
241 // cout << "color = " << color[0] << " " << color[1] << " "
242 // << color[2] << endl;
246 sgCopyVec4( ptr, color );
253 // reposition the moon at the specified right ascension and
254 // declination, offset by our current position (p) so that it appears
255 // fixed at a great distance from the viewer. Also add in an optional
256 // rotation (i.e. for the current time of day.)
257 bool SGMoon::reposition( sgVec3 p, double angle,
258 double rightAscension, double declination,
261 sgMat4 T1, T2, GST, RA, DEC;
265 sgMakeTransMat4( T1, p );
267 sgSetVec3( axis, 0.0, 0.0, -1.0 );
268 sgMakeRotMat4( GST, angle, axis );
270 // xglRotatef( ((SGD_RADIANS_TO_DEGREES * rightAscension)- 90.0),
272 sgSetVec3( axis, 0.0, 0.0, 1.0 );
273 sgMakeRotMat4( RA, (rightAscension * SGD_RADIANS_TO_DEGREES) - 90.0, axis );
275 // xglRotatef((SGD_RADIANS_TO_DEGREES * declination), 1.0, 0.0, 0.0);
276 sgSetVec3( axis, 1.0, 0.0, 0.0 );
277 sgMakeRotMat4( DEC, declination * SGD_RADIANS_TO_DEGREES, axis );
279 // xglTranslatef(0,moon_dist);
280 sgSetVec3( v, 0.0, moon_dist, 0.0 );
281 sgMakeTransMat4( T2, v );
284 sgCopyMat4( TRANSFORM, T1 );
285 sgPreMultMat4( TRANSFORM, GST );
286 sgPreMultMat4( TRANSFORM, RA );
287 sgPreMultMat4( TRANSFORM, DEC );
288 sgPreMultMat4( TRANSFORM, T2 );
291 sgSetCoord( &skypos, TRANSFORM );
293 moon_transform->setTransform( &skypos );