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 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.
27 # include <simgear_config.h>
30 #include <simgear/compiler.h>
38 #include <simgear/constants.h>
39 #include <simgear/screen/colors.hxx>
45 // Set up moon rendering call backs
46 static int sgMoonOrbPreDraw( ssgEntity *e ) {
47 /* cout << endl << "Moon orb pre draw" << endl << "----------------"
50 ssgLeaf *f = (ssgLeaf *)e;
51 if ( f -> hasState () ) f->getState()->apply() ;
53 glPushAttrib( GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT | GL_ENABLE_BIT );
54 // cout << "push error = " << glGetError() << endl;
56 glDisable( GL_DEPTH_TEST );
58 glBlendFunc ( GL_SRC_ALPHA, GL_ONE ) ;
64 static int sgMoonOrbPostDraw( ssgEntity *e ) {
65 /* cout << endl << "Moon orb post draw" << endl << "----------------"
68 // Some drivers don't properly reset glBendFunc with a
69 // glPopAttrib() so we reset it to the 'default' here.
70 glBlendFunc ( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA ) ;
73 // cout << "pop error = " << glGetError() << endl;
80 static int sgMoonHaloPreDraw( ssgEntity *e ) {
81 /* cout << endl << "Moon halo pre draw" << endl << "----------------"
84 ssgLeaf *f = (ssgLeaf *)e;
85 if ( f -> hasState () ) f->getState()->apply() ;
87 glPushAttrib( GL_DEPTH_BUFFER_BIT | GL_FOG_BIT | GL_COLOR_BUFFER_BIT);
88 // cout << "push error = " << glGetError() << endl;
90 glDisable( GL_DEPTH_TEST );
92 glBlendFunc ( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA ) ;
97 static int sgMoonHaloPostDraw( ssgEntity *e ) {
98 /* cout << endl << "Moon halo post draw" << endl << "----------------"
102 // cout << "pop error = " << glGetError() << endl;
110 SGMoon::SGMoon( void ) :
117 SGMoon::~SGMoon( void ) {
121 // build the moon object
122 ssgBranch * SGMoon::build( SGPath path, double moon_size ) {
124 // set up the orb state
125 path.append( "moon.rgba" );
126 orb_state = new ssgSimpleState();
127 orb_state->setTexture( (char *)path.c_str() );
128 orb_state->setShadeModel( GL_SMOOTH );
129 orb_state->enable( GL_LIGHTING );
130 orb_state->enable( GL_CULL_FACE );
131 orb_state->enable( GL_TEXTURE_2D );
132 orb_state->enable( GL_COLOR_MATERIAL );
133 orb_state->setColourMaterial( GL_DIFFUSE );
134 orb_state->setMaterial( GL_AMBIENT, 0, 0, 0, 1.0 );
135 orb_state->setMaterial( GL_EMISSION, 0.0, 0.0, 0.0, 1 );
136 orb_state->setMaterial( GL_SPECULAR, 0, 0, 0, 1 );
137 orb_state->enable( GL_BLEND );
138 orb_state->enable( GL_ALPHA_TEST );
139 orb_state->setAlphaClamp( 0.01 );
141 cl = new ssgColourArray( 1 );
143 sgSetVec4( color, 1.0, 1.0, 1.0, 1.0 );
146 ssgBranch *orb = ssgMakeSphere( orb_state, cl, moon_size, 15, 15,
147 sgMoonOrbPreDraw, sgMoonOrbPostDraw );
149 // force a repaint of the moon colors with arbitrary defaults
153 // moon_texbuf = new GLubyte[64*64*3];
154 // moon_texid = makeHalo( moon_texbuf, 64 );
155 // my_glWritePPMFile("moonhalo.ppm", moon_texbuf, 64, 64, RGB);
158 // set up the halo state
159 halo_state = new ssgSimpleState();
160 halo_state->setTexture( "halo.rgb" );
161 // halo_state->setTexture( moon_texid );
162 halo_state->enable( GL_TEXTURE_2D );
163 halo_state->disable( GL_LIGHTING );
164 halo_state->setShadeModel( GL_SMOOTH );
165 halo_state->disable( GL_CULL_FACE );
167 halo_state->disable( GL_COLOR_MATERIAL );
168 halo_state->setColourMaterial( GL_AMBIENT_AND_DIFFUSE );
169 halo_state->setMaterial ( GL_AMBIENT_AND_DIFFUSE, 1, 1, 1, 1 ) ;
170 halo_state->setMaterial ( GL_EMISSION, 0, 0, 0, 1 ) ;
171 halo_state->setMaterial ( GL_SPECULAR, 0, 0, 0, 1 ) ;
172 // halo_state -> setShininess ( 0 ) ;
173 halo_state->enable( GL_ALPHA_TEST );
174 halo_state->setAlphaClamp(0.01);
175 halo_state->enable ( GL_BLEND ) ;
178 // Build ssg structure
179 double size = moon_size * 10.0;
181 halo_vl = new ssgVertexArray;
182 sgSetVec3( v3, -size, 0.0, -size );
184 sgSetVec3( v3, size, 0.0, -size );
186 sgSetVec3( v3, -size, 0.0, size );
188 sgSetVec3( v3, size, 0.0, size );
192 halo_tl = new ssgTexCoordArray;
193 sgSetVec2( v2, 0.0f, 0.0f );
195 sgSetVec2( v2, 1.0, 0.0 );
197 sgSetVec2( v2, 0.0, 1.0 );
199 sgSetVec2( v2, 1.0, 1.0 );
203 new ssgVtxTable ( GL_TRIANGLE_STRIP, halo_vl, NULL, halo_tl, cl );
204 halo->setState( halo_state );
207 // build the ssg scene graph sub tree for the sky and connected
208 // into the provide scene graph branch
209 moon_transform = new ssgTransform;
211 // moon_transform->addKid( halo );
212 moon_transform->addKid( orb );
214 return moon_transform;
218 // repaint the moon colors based on current value of moon_angle in
219 // degrees relative to verticle
220 // 0 degrees = high noon
221 // 90 degrees = moon rise/set
222 // 180 degrees = darkest midnight
223 bool SGMoon::repaint( double moon_angle ) {
225 if (prev_moon_angle != moon_angle) {
226 prev_moon_angle = moon_angle;
228 float moon_factor = 4*cos(moon_angle);
230 if (moon_factor > 1) moon_factor = 1.0;
231 if (moon_factor < -1) moon_factor = -1.0;
232 moon_factor = moon_factor/2 + 0.5;
235 color[1] = sqrt(moon_factor);
236 color[0] = sqrt(color[1]);
237 color[2] = moon_factor * moon_factor;
238 color[2] *= color[2];
241 gamma_correct_rgb( color );
243 // cout << "color = " << color[0] << " " << color[1] << " "
244 // << color[2] << endl;
248 sgCopyVec4( ptr, color );
255 // reposition the moon at the specified right ascension and
256 // declination, offset by our current position (p) so that it appears
257 // fixed at a great distance from the viewer. Also add in an optional
258 // rotation (i.e. for the current time of day.)
259 bool SGMoon::reposition( sgVec3 p, double angle,
260 double rightAscension, double declination,
263 sgMat4 T1, T2, GST, RA, DEC;
267 sgMakeTransMat4( T1, p );
269 sgSetVec3( axis, 0.0, 0.0, -1.0 );
270 sgMakeRotMat4( GST, angle, axis );
272 // xglRotatef( ((SGD_RADIANS_TO_DEGREES * rightAscension)- 90.0),
274 sgSetVec3( axis, 0.0, 0.0, 1.0 );
275 sgMakeRotMat4( RA, (rightAscension * SGD_RADIANS_TO_DEGREES) - 90.0, axis );
277 // xglRotatef((SGD_RADIANS_TO_DEGREES * declination), 1.0, 0.0, 0.0);
278 sgSetVec3( axis, 1.0, 0.0, 0.0 );
279 sgMakeRotMat4( DEC, declination * SGD_RADIANS_TO_DEGREES, axis );
281 // xglTranslatef(0,moon_dist);
282 sgSetVec3( v, 0.0, moon_dist, 0.0 );
283 sgMakeTransMat4( T2, v );
286 sgCopyMat4( TRANSFORM, T1 );
287 sgPreMultMat4( TRANSFORM, GST );
288 sgPreMultMat4( TRANSFORM, RA );
289 sgPreMultMat4( TRANSFORM, DEC );
290 sgPreMultMat4( TRANSFORM, T2 );
293 sgSetCoord( &skypos, TRANSFORM );
295 moon_transform->setTransform( &skypos );