simgear/scene/sky/cloud.cxx

   1 // cloud.cxx -- model a single cloud layer
   2 //
   3 // Written by Curtis Olson, started June 2000.
   4 //
   5 // Copyright (C) 2000  Curtis L. Olson  - curt@flightgear.org
   6 //
   7 // This program is distributed in the hope that it will be useful, but
   8 // WITHOUT ANY WARRANTY; without even the implied warranty of
   9 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  10 // General Public License for more details.
  11 //
  12 // You should have received a copy of the GNU General Public License
  13 // along with this program; if not, write to the Free Software
  14 // Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  15 //
  16 // $Id$
  17
  18
  19 #include <simgear/compiler.h>
  20
  21 // #include <stdio.h>
  22 #include <math.h>
  23
  24 // #if defined (__APPLE__)
  25 // // any C++ header file undefines isinf and isnan
  26 // // so this should be included before <iostream>
  27 // inline int (isinf)(double r) { return isinf(r); }
  28 // inline int (isnan)(double r) { return isnan(r); }
  29 // #endif
  30
  31 // #include STL_IOSTREAM
  32
  33 #include <plib/sg.h>
  34 #include <plib/ssg.h>
  35
  36 #include <simgear/math/point3d.hxx>
  37 #include <simgear/math/polar3d.hxx>
  38 #include <simgear/math/sg_random.h>
  39 #include <simgear/debug/logstream.hxx>
  40 #include <simgear/misc/sg_path.hxx>
  41 #include <simgear/screen/extensions.hxx>
  42 #include <simgear/screen/texture.hxx>
  43
  44 #include "cloud.hxx"
  45
  46
  47 static ssgStateSelector *layer_states[SGCloudLayer::SG_MAX_CLOUD_COVERAGES];
  48 static bool state_initialized = false;
  49 static bool bump_mapping = false;
  50 static int nb_texture_unit = 0;
  51 static ssgTexture *normal_map[SGCloudLayer::SG_MAX_CLOUD_COVERAGES][2] = { 0 };
  52 static ssgTexture *color_map[SGCloudLayer::SG_MAX_CLOUD_COVERAGES][2] = { 0 };
  53 static GLuint normalization_cube_map;
  54
  55 static glActiveTextureProc glActiveTexturePtr = 0;
  56 static glClientActiveTextureProc glClientActiveTexturePtr = 0;
  57 static glBlendColorProc glBlendColorPtr = 0;
  58
  59 bool SGCloudLayer::enable_bump_mapping = false;
  60
  61 static void
  62 generateNormalizationCubeMap()
  63 {
  64     unsigned char data[ 32 * 32 * 3 ];
  65     const int size = 32;
  66     const float half_size = 16.0f,
  67                 offset = 0.5f;
  68     sgVec3 zero_normal;
  69     sgSetVec3( zero_normal, 0.5f, 0.5f, 0.5f );
  70     int i, j;
  71
  72     unsigned char *ptr = data;
  73     for ( j = 0; j < size; j++ ) {
  74         for ( i = 0; i < size; i++ ) {
  75             sgVec3 tmp;
  76             sgSetVec3( tmp, half_size,
  77                             -( j + offset - half_size ),
  78                             -( i + offset - half_size ) );
  79             sgNormalizeVec3( tmp );
  80             sgScaleVec3( tmp, 0.5f );
  81             sgAddVec3( tmp, zero_normal );
  82
  83             *ptr++ = (unsigned char)( tmp[ 0 ] * 255 );
  84             *ptr++ = (unsigned char)( tmp[ 1 ] * 255 );
  85             *ptr++ = (unsigned char)( tmp[ 2 ] * 255 );
  86         }
  87     }
  88     glTexImage2D( GL_TEXTURE_CUBE_MAP_POSITIVE_X_ARB,
  89                   0, GL_RGBA8, 32, 32, 0, GL_RGB, GL_UNSIGNED_BYTE, data );
  90
  91     ptr = data;
  92     for ( j = 0; j < size; j++ ) {
  93         for ( i = 0; i < size; i++ ) {
  94             sgVec3 tmp;
  95             sgSetVec3( tmp, -half_size,
  96                             -( j + offset - half_size ),
  97                             ( i + offset - half_size ) );
  98             sgNormalizeVec3( tmp );
  99             sgScaleVec3( tmp, 0.5f );
 100             sgAddVec3( tmp, zero_normal );
 101
 102             *ptr++ = (unsigned char)( tmp[ 0 ] * 255 );
 103             *ptr++ = (unsigned char)( tmp[ 1 ] * 255 );
 104             *ptr++ = (unsigned char)( tmp[ 2 ] * 255 );
 105         }
 106     }
 107     glTexImage2D( GL_TEXTURE_CUBE_MAP_NEGATIVE_X_ARB,
 108                   0, GL_RGBA8, 32, 32, 0, GL_RGB, GL_UNSIGNED_BYTE, data );
 109
 110     ptr = data;
 111     for ( j = 0; j < size; j++ ) {
 112         for ( i = 0; i < size; i++ ) {
 113             sgVec3 tmp;
 114             sgSetVec3( tmp, ( i + offset - half_size ),
 115                             half_size,
 116                             ( j + offset - half_size ) );
 117             sgNormalizeVec3( tmp );
 118             sgScaleVec3( tmp, 0.5f );
 119             sgAddVec3( tmp, zero_normal );
 120
 121             *ptr++ = (unsigned char)( tmp[ 0 ] * 255 );
 122             *ptr++ = (unsigned char)( tmp[ 1 ] * 255 );
 123             *ptr++ = (unsigned char)( tmp[ 2 ] * 255 );
 124         }
 125     }
 126     glTexImage2D( GL_TEXTURE_CUBE_MAP_POSITIVE_Y_ARB,
 127                   0, GL_RGBA8, 32, 32, 0, GL_RGB, GL_UNSIGNED_BYTE, data );
 128
 129     ptr = data;
 130     for ( j = 0; j < size; j++ ) {
 131         for ( i = 0; i < size; i++ ) {
 132             sgVec3 tmp;
 133             sgSetVec3( tmp, ( i + offset - half_size ),
 134                             -half_size,
 135                             -( j + offset - half_size ) );
 136             sgNormalizeVec3( tmp );
 137             sgScaleVec3( tmp, 0.5f );
 138             sgAddVec3( tmp, zero_normal );
 139
 140             *ptr++ = (unsigned char)( tmp[ 0 ] * 255 );
 141             *ptr++ = (unsigned char)( tmp[ 1 ] * 255 );
 142             *ptr++ = (unsigned char)( tmp[ 2 ] * 255 );
 143         }
 144     }
 145     glTexImage2D( GL_TEXTURE_CUBE_MAP_NEGATIVE_Y_ARB,
 146                   0, GL_RGBA8, 32, 32, 0, GL_RGB, GL_UNSIGNED_BYTE, data );
 147
 148     ptr = data;
 149     for ( j = 0; j < size; j++ ) {
 150         for ( i = 0; i < size; i++ ) {
 151             sgVec3 tmp;
 152             sgSetVec3( tmp, ( i + offset - half_size ),
 153                             -( j + offset - half_size ),
 154                             half_size );
 155             sgNormalizeVec3( tmp );
 156             sgScaleVec3( tmp, 0.5f );
 157             sgAddVec3( tmp, zero_normal );
 158
 159             *ptr++ = (unsigned char)( tmp[ 0 ] * 255 );
 160             *ptr++ = (unsigned char)( tmp[ 1 ] * 255 );
 161             *ptr++ = (unsigned char)( tmp[ 2 ] * 255 );
 162         }
 163     }
 164     glTexImage2D( GL_TEXTURE_CUBE_MAP_POSITIVE_Z_ARB,
 165                   0, GL_RGBA8, 32, 32, 0, GL_RGB, GL_UNSIGNED_BYTE, data );
 166
 167     ptr = data;
 168     for ( j = 0; j < size; j++ ) {
 169         for ( i = 0; i < size; i++ ) {
 170             sgVec3 tmp;
 171             sgSetVec3( tmp, -( i + offset - half_size ),
 172                             -( j + offset - half_size ),
 173                             -half_size );
 174             sgNormalizeVec3( tmp );
 175             sgScaleVec3( tmp, 0.5f );
 176             sgAddVec3( tmp, zero_normal );
 177
 178             *ptr++ = (unsigned char)( tmp[ 0 ] * 255 );
 179             *ptr++ = (unsigned char)( tmp[ 1 ] * 255 );
 180             *ptr++ = (unsigned char)( tmp[ 2 ] * 255 );
 181         }
 182     }
 183     glTexImage2D( GL_TEXTURE_CUBE_MAP_NEGATIVE_Z_ARB,
 184                   0, GL_RGBA8, 32, 32, 0, GL_RGB, GL_UNSIGNED_BYTE, data );
 185 }
 186
 187
 188 // Constructor
 189 SGCloudLayer::SGCloudLayer( const string &tex_path ) :
 190     layer_root(new ssgRoot),
 191     layer_transform(new ssgTransform),
 192     state_sel(0),
 193     texture_path(tex_path),
 194     layer_span(0.0),
 195     layer_asl(0.0),
 196     layer_thickness(0.0),
 197     layer_transition(0.0),
 198     layer_coverage(SG_CLOUD_CLEAR),
 199     scale(4000.0),
 200     speed(0.0),
 201     direction(0.0),
 202     last_lon(0.0),
 203     last_lat(0.0),
 204     vertices(0),
 205     indices(0)
 206 {
 207     cl[0] = cl[1] = cl[2] = cl[3] = NULL;
 208     vl[0] = vl[1] = vl[2] = vl[3] = NULL;
 209     tl[0] = tl[1] = tl[2] = tl[3] = NULL;
 210     layer[0] = layer[1] = layer[2] = layer[3] = NULL;
 211
 212     layer_root->addKid(layer_transform);
 213     rebuild();
 214 }
 215
 216 // Destructor
 217 SGCloudLayer::~SGCloudLayer()
 218 {
 219     delete vertices;
 220     delete indices;
 221     delete layer_root;          // deletes layer_transform and layer as well
 222 }
 223
 224 float
 225 SGCloudLayer::getSpan_m () const
 226 {
 227     return layer_span;
 228 }
 229
 230 void
 231 SGCloudLayer::setSpan_m (float span_m)
 232 {
 233     if (span_m != layer_span) {
 234         layer_span = span_m;
 235         rebuild();
 236     }
 237 }
 238
 239 float
 240 SGCloudLayer::getElevation_m () const
 241 {
 242     return layer_asl;
 243 }
 244
 245 void
 246 SGCloudLayer::setElevation_m (float elevation_m, bool set_span)
 247 {
 248     layer_asl = elevation_m;
 249
 250     if (set_span) {
 251         if (elevation_m > 4000)
 252             setSpan_m(  elevation_m * 10 );
 253         else
 254             setSpan_m( 40000 );
 255     }
 256 }
 257
 258 float
 259 SGCloudLayer::getThickness_m () const
 260 {
 261     return layer_thickness;
 262 }
 263
 264 void
 265 SGCloudLayer::setThickness_m (float thickness_m)
 266 {
 267     layer_thickness = thickness_m;
 268 }
 269
 270 float
 271 SGCloudLayer::getTransition_m () const
 272 {
 273     return layer_transition;
 274 }
 275
 276 void
 277 SGCloudLayer::setTransition_m (float transition_m)
 278 {
 279     layer_transition = transition_m;
 280 }
 281
 282 SGCloudLayer::Coverage
 283 SGCloudLayer::getCoverage () const
 284 {
 285     return layer_coverage;
 286 }
 287
 288 void
 289 SGCloudLayer::setCoverage (Coverage coverage)
 290 {
 291     if (coverage != layer_coverage) {
 292         layer_coverage = coverage;
 293         rebuild();
 294     }
 295 }
 296
 297
 298 // build the cloud object
 299 void
 300 SGCloudLayer::rebuild()
 301 {
 302     // Initialize states and sizes if necessary.
 303     if ( !state_initialized ) {
 304         state_initialized = true;
 305
 306         SG_LOG(SG_ASTRO, SG_INFO, "initializing cloud layers");
 307
 308         bump_mapping = SGIsOpenGLExtensionSupported("GL_ARB_multitexture") &&
 309                        SGIsOpenGLExtensionSupported("GL_ARB_texture_cube_map") &&
 310                        SGIsOpenGLExtensionSupported("GL_ARB_texture_env_combine") &&
 311                        SGIsOpenGLExtensionSupported("GL_ARB_texture_env_dot3") &&
 312                        SGIsOpenGLExtensionSupported("GL_ARB_imaging");
 313
 314         if ( bump_mapping ) {
 315             glGetIntegerv( GL_MAX_TEXTURE_UNITS_ARB, &nb_texture_unit );
 316             if ( nb_texture_unit < 2 ) {
 317                 bump_mapping = false;
 318             }
 319             nb_texture_unit = 2; // Force the number of units for now
 320         }
 321
 322         if ( bump_mapping ) {
 323
 324             // This bump mapping code was inspired by the tutorial available at
 325             // http://www.paulsprojects.net/tutorials/simplebump/simplebump.html
 326             // and a NVidia white paper
 327             //  http://developer.nvidia.com/object/bumpmappingwithregistercombiners.html
 328             // The normal map textures were generated by the normal map Gimp plugin :
 329             //  http://nifelheim.dyndns.org/~cocidius/normalmap/
 330             //
 331             SGPath cloud_path;
 332
 333             glActiveTexturePtr = (glActiveTextureProc)SGLookupFunction("glActiveTextureARB");
 334             glClientActiveTexturePtr = (glClientActiveTextureProc)SGLookupFunction("glClientActiveTextureARB");
 335             glBlendColorPtr = (glBlendColorProc)SGLookupFunction("glBlendColor");
 336
 337             cloud_path.set(texture_path.str());
 338             cloud_path.append("overcast.rgb");
 339             color_map[ SG_CLOUD_OVERCAST ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 340             color_map[ SG_CLOUD_OVERCAST ][ 0 ]->ref();
 341             cloud_path.set(texture_path.str());
 342             cloud_path.append("overcast_n.rgb");
 343             normal_map[ SG_CLOUD_OVERCAST ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 344             normal_map[ SG_CLOUD_OVERCAST ][ 0 ]->ref();
 345
 346             cloud_path.set(texture_path.str());
 347             cloud_path.append("overcast_top.rgb");
 348             color_map[ SG_CLOUD_OVERCAST ][ 1 ] = new ssgTexture( cloud_path.str().c_str() );
 349             color_map[ SG_CLOUD_OVERCAST ][ 1 ]->ref();
 350             cloud_path.set(texture_path.str());
 351             cloud_path.append("overcast_top_n.rgb");
 352             normal_map[ SG_CLOUD_OVERCAST ][ 1 ] = new ssgTexture( cloud_path.str().c_str() );
 353             normal_map[ SG_CLOUD_OVERCAST ][ 1 ]->ref();
 354
 355             cloud_path.set(texture_path.str());
 356             cloud_path.append("broken.rgba");
 357             color_map[ SG_CLOUD_BROKEN ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 358             color_map[ SG_CLOUD_BROKEN ][ 0 ]->ref();
 359             cloud_path.set(texture_path.str());
 360             cloud_path.append("broken_n.rgb");
 361             normal_map[ SG_CLOUD_BROKEN ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 362             normal_map[ SG_CLOUD_BROKEN ][ 0 ]->ref();
 363
 364             cloud_path.set(texture_path.str());
 365             cloud_path.append("scattered.rgba");
 366             color_map[ SG_CLOUD_SCATTERED ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 367             color_map[ SG_CLOUD_SCATTERED ][ 0 ]->ref();
 368             cloud_path.set(texture_path.str());
 369             cloud_path.append("scattered_n.rgb");
 370             normal_map[ SG_CLOUD_SCATTERED ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 371             normal_map[ SG_CLOUD_SCATTERED ][ 0 ]->ref();
 372
 373             cloud_path.set(texture_path.str());
 374             cloud_path.append("few.rgba");
 375             color_map[ SG_CLOUD_FEW ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 376             color_map[ SG_CLOUD_FEW ][ 0 ]->ref();
 377             cloud_path.set(texture_path.str());
 378             cloud_path.append("few_n.rgb");
 379             normal_map[ SG_CLOUD_FEW ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 380             normal_map[ SG_CLOUD_FEW ][ 0 ]->ref();
 381
 382             cloud_path.set(texture_path.str());
 383             cloud_path.append("cirrus.rgba");
 384             color_map[ SG_CLOUD_CIRRUS ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 385             color_map[ SG_CLOUD_CIRRUS ][ 0 ]->ref();
 386             cloud_path.set(texture_path.str());
 387             cloud_path.append("cirrus_n.rgb");
 388             normal_map[ SG_CLOUD_CIRRUS ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 389             normal_map[ SG_CLOUD_CIRRUS ][ 0 ]->ref();
 390
 391             glGenTextures( 1, &normalization_cube_map );
 392             glBindTexture( GL_TEXTURE_CUBE_MAP_ARB, normalization_cube_map );
 393             generateNormalizationCubeMap();
 394             glTexParameteri( GL_TEXTURE_CUBE_MAP_ARB, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
 395             glTexParameteri( GL_TEXTURE_CUBE_MAP_ARB, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
 396             glTexParameteri( GL_TEXTURE_CUBE_MAP_ARB, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );
 397             glTexParameteri( GL_TEXTURE_CUBE_MAP_ARB, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE );
 398             glTexParameteri( GL_TEXTURE_CUBE_MAP_ARB, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE );
 399         } /* else */ {
 400             SGPath cloud_path;
 401             ssgStateSelector *state_sel;
 402             ssgSimpleState *state;
 403
 404             state_sel = new ssgStateSelector( 2 );
 405             state_sel->ref();
 406             cloud_path.set(texture_path.str());
 407             cloud_path.append("overcast.rgb");
 408             state_sel->setStep( 0, sgCloudMakeState(cloud_path.str()) );
 409             cloud_path.set(texture_path.str());
 410             cloud_path.append("overcast_top.rgb");
 411             state_sel->setStep( 1, sgCloudMakeState(cloud_path.str()) );
 412             layer_states[SG_CLOUD_OVERCAST] = state_sel;
 413
 414             state_sel = new ssgStateSelector( 2 );
 415             state_sel->ref();
 416             cloud_path.set(texture_path.str());
 417             cloud_path.append("broken.rgba");
 418             state = sgCloudMakeState(cloud_path.str());
 419             state_sel->setStep( 0, state );
 420             state_sel->setStep( 1, state );
 421             layer_states[SG_CLOUD_BROKEN] = state_sel;
 422
 423             state_sel = new ssgStateSelector( 2 );
 424             state_sel->ref();
 425             cloud_path.set(texture_path.str());
 426             cloud_path.append("scattered.rgba");
 427             state = sgCloudMakeState(cloud_path.str());
 428             state_sel->setStep( 0, state );
 429             state_sel->setStep( 1, state );
 430             layer_states[SG_CLOUD_SCATTERED] = state_sel;
 431
 432             state_sel = new ssgStateSelector( 2 );
 433             state_sel->ref();
 434             cloud_path.set(texture_path.str());
 435             cloud_path.append("few.rgba");
 436             state = sgCloudMakeState(cloud_path.str());
 437             state_sel->setStep( 0, state );
 438             state_sel->setStep( 1, state );
 439             layer_states[SG_CLOUD_FEW] = state_sel;
 440
 441             state_sel = new ssgStateSelector( 2 );
 442             state_sel->ref();
 443             cloud_path.set(texture_path.str());
 444             cloud_path.append("cirrus.rgba");
 445             state = sgCloudMakeState(cloud_path.str());
 446             state_sel->setStep( 0, state );
 447             state_sel->setStep( 1, state );
 448             layer_states[SG_CLOUD_CIRRUS] = state_sel;
 449
 450             layer_states[SG_CLOUD_CLEAR] = 0;
 451         }
 452     }
 453
 454     if ( bump_mapping ) {
 455
 456         if ( !vertices ) {
 457             vertices = new CloudVertex[ 25 ];
 458             indices = new unsigned int[ 40 ];
 459         }
 460
 461         sgVec2 base;
 462         sgSetVec2( base, sg_random(), sg_random() );
 463
 464         const float layer_scale = layer_span / scale;
 465         const float layer_to_core = (SG_EARTH_RAD * 1000 + layer_asl);
 466         const float half_angle = 0.5 * layer_span / layer_to_core;
 467
 468         int i;
 469         for ( i = -2; i <= 2; i++ ) {
 470             for ( int j = -2; j <= 2; j++ ) {
 471                 CloudVertex &v1 = vertices[ (i+2)*5 + (j+2) ];
 472                 sgSetVec3( v1.position,
 473                            0.5 * i * layer_span,
 474                            0.5 * j * layer_span,
 475                            -layer_to_core * ( 1 - cos( i * half_angle ) * cos( j * half_angle ) ) );
 476                 sgSetVec2( v1.texCoord,
 477                            base[0] + layer_scale * i * 0.25,
 478                            base[1] + layer_scale * j * 0.25 );
 479                 sgSetVec3( v1.sTangent,
 480                            cos( i * half_angle ),
 481                            0.f,
 482                            -sin( i * half_angle ) );
 483                 sgSetVec3( v1.tTangent,
 484                            0.f,
 485                            cos( j * half_angle ),
 486                            -sin( j * half_angle ) );
 487                 sgVectorProductVec3( v1.normal, v1.tTangent, v1.sTangent );
 488                 sgSetVec4( v1.color, 1.0f, 1.0f, 1.0f, (i == 0) ? 0.0f : 0.15f );
 489             }
 490         }
 491         /*
 492          * 0 1 5 6 10 11 15 16 20 21
 493          * 1 2 6 7 11 12 16 17 21 22
 494          * 2 3 7 8 12 13 17 18 22 23
 495          * 3 4 8 9 13 14 18 19 23 24
 496          */
 497         for ( i = 0; i < 4; i++ ) {
 498             for ( int j = 0; j < 5; j++ ) {
 499                 indices[ i*10 + (j*2) ]     =     i + 5 * j;
 500                 indices[ i*10 + (j*2) + 1 ] = 1 + i + 5 * j;
 501             }
 502         }
 503
 504     } /* else */ {
 505
 506         scale = 4000.0;
 507         last_lon = last_lat = -999.0f;
 508
 509         sgVec2 base;
 510         sgSetVec2( base, sg_random(), sg_random() );
 511
 512         // build the cloud layer
 513         sgVec4 color;
 514         sgVec3 vertex;
 515         sgVec2 tc;
 516
 517         const float layer_scale = layer_span / scale;
 518         const float mpi = SG_PI/4;
 519
 520         // caclculate the difference between a flat-earth model and
 521         // a round earth model given the span and altutude ASL of
 522         // the cloud layer. This is the difference in altitude between
 523         // the top of the inverted bowl and the edge of the bowl.
 524         // const float alt_diff = layer_asl * 0.8;
 525         const float layer_to_core = (SG_EARTH_RAD * 1000 + layer_asl);
 526         const float layer_angle = 0.5*layer_span / layer_to_core; // The angle is half the span
 527         const float border_to_core = layer_to_core * cos(layer_angle);
 528         const float alt_diff = layer_to_core - border_to_core;
 529
 530         for (int i = 0; i < 4; i++)
 531         {
 532             if ( layer[i] != NULL ) {
 533                 layer_transform->removeKid(layer[i]); // automatic delete
 534             }
 535
 536             vl[i] = new ssgVertexArray( 10 );
 537             cl[i] = new ssgColourArray( 10 );
 538             tl[i] = new ssgTexCoordArray( 10 );
 539
 540
 541             sgSetVec3( vertex, layer_span*(i-2)/2, -layer_span,
 542                             alt_diff * (sin(i*mpi) - 2) );
 543
 544             sgSetVec2( tc, base[0] + layer_scale * i/4, base[1] );
 545
 546             sgSetVec4( color, 1.0f, 1.0f, 1.0f, (i == 0) ? 0.0f : 0.15f );
 547
 548             cl[i]->add( color );
 549             vl[i]->add( vertex );
 550             tl[i]->add( tc );
 551
 552             for (int j = 0; j < 4; j++)
 553             {
 554                 sgSetVec3( vertex, layer_span*(i-1)/2, layer_span*(j-2)/2,
 555                                 alt_diff * (sin((i+1)*mpi) + sin(j*mpi) - 2) );
 556
 557                 sgSetVec2( tc, base[0] + layer_scale * (i+1)/4,
 558                             base[1] + layer_scale * j/4 );
 559
 560                 sgSetVec4( color, 1.0f, 1.0f, 1.0f,
 561                                 ( (j == 0) || (i == 3)) ?
 562                                 ( (j == 0) && (i == 3)) ? 0.0f : 0.15f : 1.0f );
 563
 564                 cl[i]->add( color );
 565                 vl[i]->add( vertex );
 566                 tl[i]->add( tc );
 567
 568
 569                 sgSetVec3( vertex, layer_span*(i-2)/2, layer_span*(j-1)/2,
 570                                 alt_diff * (sin(i*mpi) + sin((j+1)*mpi) - 2) );
 571
 572                 sgSetVec2( tc, base[0] + layer_scale * i/4,
 573                             base[1] + layer_scale * (j+1)/4 );
 574
 575                 sgSetVec4( color, 1.0f, 1.0f, 1.0f,
 576                                 ((j == 3) || (i == 0)) ?
 577                                 ((j == 3) && (i == 0)) ? 0.0f : 0.15f : 1.0f );
 578                 cl[i]->add( color );
 579                 vl[i]->add( vertex );
 580                 tl[i]->add( tc );
 581             }
 582
 583             sgSetVec3( vertex, layer_span*(i-1)/2, layer_span,
 584                             alt_diff * (sin((i+1)*mpi) - 2) );
 585
 586             sgSetVec2( tc, base[0] + layer_scale * (i+1)/4,
 587                         base[1] + layer_scale );
 588
 589             sgSetVec4( color, 1.0f, 1.0f, 1.0f, (i == 3) ? 0.0f : 0.15f );
 590
 591             cl[i]->add( color );
 592             vl[i]->add( vertex );
 593             tl[i]->add( tc );
 594
 595             layer[i] = new ssgVtxTable(GL_TRIANGLE_STRIP, vl[i], NULL, tl[i], cl[i]);
 596             layer_transform->addKid( layer[i] );
 597
 598             if ( layer_states[layer_coverage] != NULL ) {
 599                 layer[i]->setState( layer_states[layer_coverage] );
 600             }
 601             state_sel = layer_states[layer_coverage];
 602         }
 603
 604         // force a repaint of the sky colors with arbitrary defaults
 605         repaint( color );
 606     }
 607 }
 608
 609
 610 // repaint the cloud layer colors
 611 bool SGCloudLayer::repaint( sgVec3 fog_color ) {
 612
 613     if ( bump_mapping && enable_bump_mapping ) {
 614
 615         for ( int i = 0; i < 25; i++ ) {
 616             sgCopyVec3( vertices[ i ].color, fog_color );
 617         }
 618
 619     } else {
 620         float *color;
 621
 622         for ( int i = 0; i < 4; i++ ) {
 623             for ( int j = 0; j < 10; ++j ) {
 624                 color = cl[i]->get( j );
 625                 sgCopyVec3( color, fog_color );
 626             }
 627         }
 628     }
 629
 630     return true;
 631 }
 632
 633
 634 // reposition the cloud layer at the specified origin and orientation
 635 // lon specifies a rotation about the Z axis
 636 // lat specifies a rotation about the new Y axis
 637 // spin specifies a rotation about the new Z axis (and orients the
 638 // sunrise/set effects
 639 bool SGCloudLayer::reposition( sgVec3 p, sgVec3 up, double lon, double lat,
 640                                double alt, double dt )
 641 {
 642     sgMat4 T1, LON, LAT;
 643     sgVec3 axis;
 644
 645     // combine p and asl (meters) to get translation offset
 646     sgVec3 asl_offset;
 647     sgCopyVec3( asl_offset, up );
 648     sgNormalizeVec3( asl_offset );
 649     if ( alt <= layer_asl ) {
 650         sgScaleVec3( asl_offset, layer_asl );
 651     } else {
 652         sgScaleVec3( asl_offset, layer_asl + layer_thickness );
 653     }
 654     // cout << "asl_offset = " << asl_offset[0] << "," << asl_offset[1]
 655     //      << "," << asl_offset[2] << endl;
 656     sgAddVec3( asl_offset, p );
 657     // cout << "  asl_offset = " << asl_offset[0] << "," << asl_offset[1]
 658     //      << "," << asl_offset[2] << endl;
 659
 660     // Translate to zero elevation
 661     // Point3D zero_elev = current_view.get_cur_zero_elev();
 662     sgMakeTransMat4( T1, asl_offset );
 663
 664     // printf("  Translated to %.2f %.2f %.2f\n",
 665     //        zero_elev.x, zero_elev.y, zero_elev.z );
 666
 667     // Rotate to proper orientation
 668     // printf("  lon = %.2f  lat = %.2f\n",
 669     //        lon * SGD_RADIANS_TO_DEGREES,
 670     //        lat * SGD_RADIANS_TO_DEGREES);
 671     sgSetVec3( axis, 0.0, 0.0, 1.0 );
 672     sgMakeRotMat4( LON, lon * SGD_RADIANS_TO_DEGREES, axis );
 673
 674     sgSetVec3( axis, 0.0, 1.0, 0.0 );
 675     sgMakeRotMat4( LAT, 90.0 - lat * SGD_RADIANS_TO_DEGREES, axis );
 676
 677     sgMat4 TRANSFORM;
 678
 679     sgCopyMat4( TRANSFORM, T1 );
 680     sgPreMultMat4( TRANSFORM, LON );
 681     sgPreMultMat4( TRANSFORM, LAT );
 682
 683     sgCoord layerpos;
 684     sgSetCoord( &layerpos, TRANSFORM );
 685
 686     layer_transform->setTransform( &layerpos );
 687
 688     // now calculate update texture coordinates
 689     if ( last_lon < -900 ) {
 690         last_lon = lon;
 691         last_lat = lat;
 692     }
 693
 694     double sp_dist = speed*dt;
 695
 696     if ( lon != last_lon || lat != last_lat || sp_dist != 0 ) {
 697         Point3D start( last_lon, last_lat, 0.0 );
 698         Point3D dest( lon, lat, 0.0 );
 699         double course = 0.0, dist = 0.0;
 700
 701         calc_gc_course_dist( dest, start, &course, &dist );
 702         // cout << "course = " << course << ", dist = " << dist << endl;
 703
 704         // if start and dest are too close together,
 705         // calc_gc_course_dist() can return a course of "nan".  If
 706         // this happens, lets just use the last known good course.
 707         // This is a hack, and it would probably be better to make
 708         // calc_gc_course_dist() more robust.
 709         if ( isnan(course) ) {
 710             course = last_course;
 711         } else {
 712             last_course = course;
 713         }
 714
 715         // calculate cloud movement due to external forces
 716         double ax = 0.0, ay = 0.0, bx = 0.0, by = 0.0;
 717
 718         if (dist > 0.0) {
 719             ax = cos(course) * dist;
 720             ay = sin(course) * dist;
 721         }
 722
 723         if (sp_dist > 0) {
 724             bx = cos(-direction * SGD_DEGREES_TO_RADIANS) * sp_dist;
 725             by = sin(-direction * SGD_DEGREES_TO_RADIANS) * sp_dist;
 726         }
 727
 728
 729         double xoff = (ax + bx) / (2 * scale);
 730         double yoff = (ay + by) / (2 * scale);
 731
 732         const float layer_scale = layer_span / scale;
 733
 734         // cout << "xoff = " << xoff << ", yoff = " << yoff << endl;
 735
 736         float *base;
 737         if ( bump_mapping && enable_bump_mapping ) {
 738             base = vertices[12].texCoord;
 739         } else {
 740             base = tl[0]->get( 0 );
 741         }
 742         base[0] += xoff;
 743
 744         // the while loops can lead to *long* pauses if base[0] comes
 745         // with a bogus value.
 746         // while ( base[0] > 1.0 ) { base[0] -= 1.0; }
 747         // while ( base[0] < 0.0 ) { base[0] += 1.0; }
 748         if ( base[0] > -10.0 && base[0] < 10.0 ) {
 749             base[0] -= (int)base[0];
 750         } else {
 751             SG_LOG(SG_ASTRO, SG_DEBUG,
 752                 "Error: base = " << base[0] << "," << base[1] <<
 753                 " course = " << course << " dist = " << dist );
 754             base[0] = 0.0;
 755         }
 756
 757         base[1] += yoff;
 758         // the while loops can lead to *long* pauses if base[0] comes
 759         // with a bogus value.
 760         // while ( base[1] > 1.0 ) { base[1] -= 1.0; }
 761         // while ( base[1] < 0.0 ) { base[1] += 1.0; }
 762         if ( base[1] > -10.0 && base[1] < 10.0 ) {
 763             base[1] -= (int)base[1];
 764         } else {
 765             SG_LOG(SG_ASTRO, SG_ALERT,
 766                     "Error: base = " << base[0] << "," << base[1] <<
 767                     " course = " << course << " dist = " << dist );
 768             base[1] = 0.0;
 769         }
 770
 771         if ( bump_mapping && enable_bump_mapping ) {
 772
 773             for ( int i = -2; i <= 2; i++ ) {
 774                 for ( int j = -2; j <= 2; j++ ) {
 775                     if ( i == 0 && j == 0 )
 776                         continue; // Already done on base
 777                     CloudVertex &v1 = vertices[ (i+2)*5 + (j+2) ];
 778                     sgSetVec2( v1.texCoord,
 779                             base[0] + layer_scale * i * 0.25,
 780                             base[1] + layer_scale * j * 0.25 );
 781                 }
 782             }
 783
 784         } else {
 785                 // cout << "base = " << base[0] << "," << base[1] << endl;
 786
 787             float *tc;
 788             for (int i = 0; i < 4; i++) {
 789                 tc = tl[i]->get( 0 );
 790                 sgSetVec2( tc, base[0] + layer_scale * i/4, base[1] );
 791
 792                 for (int j = 0; j < 4; j++)
 793                 {
 794                     tc = tl[i]->get( j*2+1 );
 795                     sgSetVec2( tc, base[0] + layer_scale * (i+1)/4,
 796                                 base[1] + layer_scale * j/4 );
 797
 798                     tc = tl[i]->get( (j+1)*2 );
 799                     sgSetVec2( tc, base[0] + layer_scale * i/4,
 800                                 base[1] + layer_scale * (j+1)/4 );
 801                 }
 802
 803                 tc = tl[i]->get( 9 );
 804                 sgSetVec2( tc, base[0] + layer_scale * (i+1)/4,
 805                             base[1] + layer_scale );
 806             }
 807         }
 808
 809         last_lon = lon;
 810         last_lat = lat;
 811     }
 812
 813     return true;
 814 }
 815
 816
 817 void SGCloudLayer::draw( bool top ) {
 818     if ( layer_coverage != SG_CLOUD_CLEAR ) {
 819
 820         if ( bump_mapping && enable_bump_mapping ) {
 821
 822             sgMat4 modelview,
 823                    tmp,
 824                    transform;
 825             ssgGetModelviewMatrix( modelview );
 826             layer_transform->getTransform( transform );
 827
 828             sgInvertMat4( tmp, transform );
 829
 830             sgPostMultMat4( transform, modelview );
 831             ssgLoadModelviewMatrix( transform );
 832
 833             sgVec3 lightVec;
 834             ssgGetLight( 0 )->getPosition( lightVec );
 835             sgNegateVec3( lightVec );
 836             sgXformVec3( lightVec, tmp );
 837
 838             for ( int i = 0; i < 25; i++ ) {
 839                 CloudVertex &v = vertices[ i ];
 840                 sgSetVec3( v.tangentSpLight,
 841                            sgScalarProductVec3( v.sTangent, lightVec ),
 842                            sgScalarProductVec3( v.tTangent, lightVec ),
 843                            sgScalarProductVec3( v.normal, lightVec ) );
 844             }
 845
 846             ssgTexture *decal = color_map[ layer_coverage ][ top ? 1 : 0 ];
 847             if ( top && decal == 0 ) {
 848                 decal = color_map[ layer_coverage ][ 0 ];
 849             }
 850             ssgTexture *normal = normal_map[ layer_coverage ][ top ? 1 : 0 ];
 851             if ( top && normal == 0 ) {
 852                 normal = normal_map[ layer_coverage ][ 0 ];
 853             }
 854
 855             glDisable( GL_LIGHTING );
 856             glDisable( GL_CULL_FACE );
 857             if ( layer_coverage == SG_CLOUD_FEW ) {
 858                 glEnable( GL_ALPHA_TEST );
 859                 glAlphaFunc ( GL_GREATER, 0.01 );
 860             }
 861             glEnable( GL_BLEND );
 862             glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
 863
 864             glPolygonMode( GL_FILL, GL_FRONT_AND_BACK );
 865             glShadeModel( GL_SMOOTH );
 866             glEnable( GL_COLOR_MATERIAL );
 867             sgVec4 color;
 868             sgSetVec4( color, 0.05, 0.05, 0.05, 0.0 );
 869             glMaterialfv( GL_FRONT_AND_BACK, GL_EMISSION, color );
 870             sgSetVec4( color, 0.8, 0.8, 0.8, 0.0 );
 871             glMaterialfv( GL_FRONT_AND_BACK, GL_AMBIENT, color );
 872             sgSetVec4( color, 0.5, 0.5, 0.5, 0.0 );
 873             glMaterialfv( GL_FRONT_AND_BACK, GL_DIFFUSE, color );
 874             sgSetVec4( color, 1.0, 1.0, 1.0, 1.0 );
 875             glMaterialfv( GL_FRONT_AND_BACK, GL_SPECULAR, color );
 876
 877             glActiveTexturePtr( GL_TEXTURE0_ARB );
 878             glBindTexture( GL_TEXTURE_2D, normal->getHandle() );
 879             glEnable( GL_TEXTURE_2D );
 880
 881             //Bind normalisation cube map to texture unit 1
 882             glActiveTexturePtr( GL_TEXTURE1_ARB );
 883             glBindTexture( GL_TEXTURE_CUBE_MAP_ARB, normalization_cube_map );
 884             glEnable( GL_TEXTURE_CUBE_MAP_ARB );
 885             glActiveTexturePtr( GL_TEXTURE0_ARB );
 886
 887             //Set vertex arrays for cloud
 888             glVertexPointer( 3, GL_FLOAT, sizeof(CloudVertex), &vertices[0].position );
 889             glEnableClientState( GL_VERTEX_ARRAY );
 890
 891             if ( nb_texture_unit >= 3 ) {
 892                 glColorPointer( 4, GL_FLOAT, sizeof(CloudVertex), &vertices[0].color );
 893                 glEnableClientState( GL_COLOR_ARRAY );
 894             }
 895
 896             //Send texture coords for normal map to unit 0
 897             glTexCoordPointer( 2, GL_FLOAT, sizeof(CloudVertex), &vertices[0].texCoord );
 898             glEnableClientState( GL_TEXTURE_COORD_ARRAY );
 899
 900             //Send tangent space light vectors for normalisation to unit 1
 901             glClientActiveTexturePtr( GL_TEXTURE1_ARB );
 902             glTexCoordPointer( 3, GL_FLOAT, sizeof(CloudVertex), &vertices[0].tangentSpLight );
 903             glEnableClientState( GL_TEXTURE_COORD_ARRAY );
 904
 905             //Set up texture environment to do (tex0 dot tex1)*color
 906             glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_ARB );
 907             glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_RGB_ARB, GL_TEXTURE );
 908             glTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_RGB_ARB, GL_REPLACE );
 909             glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_ALPHA_ARB, GL_TEXTURE );
 910             glTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_ALPHA_ARB, GL_REPLACE );
 911
 912             glActiveTexturePtr( GL_TEXTURE1_ARB );
 913
 914             glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_ARB );
 915             glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_RGB_ARB, GL_TEXTURE );
 916             glTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_RGB_ARB, GL_DOT3_RGB_ARB );
 917             glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE1_RGB_ARB, GL_PREVIOUS_ARB );
 918             glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_ALPHA_ARB, GL_PREVIOUS_ARB );
 919             glTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_ALPHA_ARB, GL_REPLACE );
 920
 921             if ( nb_texture_unit >= 3 ) {
 922                 glActiveTexturePtr( GL_TEXTURE2_ARB );
 923                 glBindTexture( GL_TEXTURE_2D, decal->getHandle() );
 924
 925                 glClientActiveTexturePtr( GL_TEXTURE2_ARB );
 926                 glTexCoordPointer( 2, GL_FLOAT, sizeof(CloudVertex), &vertices[0].texCoord );
 927                 glEnableClientState( GL_TEXTURE_COORD_ARRAY );
 928
 929                 sgVec4 factors;
 930                 if ( top || layer_coverage != SG_CLOUD_OVERCAST ) {
 931                     sgSetVec4( factors, 0.5f, 0.5f, 0.3f, 1.0f );
 932                 } else {
 933                     sgSetVec4( factors, 0.1f, 0.1f, 0.0f, 1.0f );
 934                 }
 935                 glTexEnvfv( GL_TEXTURE_ENV, GL_TEXTURE_ENV_COLOR, factors );
 936
 937                 glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_ARB );
 938                 glTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_RGB_ARB, GL_INTERPOLATE_ARB );
 939                 glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_RGB_ARB, GL_TEXTURE );
 940                 glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE1_RGB_ARB, GL_PREVIOUS_ARB );
 941                 glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE2_RGB_ARB, GL_CONSTANT_ARB );
 942
 943                 glClientActiveTexturePtr( GL_TEXTURE0_ARB );
 944                 glActiveTexturePtr( GL_TEXTURE0_ARB );
 945
 946                 //Draw cloud layer
 947                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[0] );
 948                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[10] );
 949                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[20] );
 950                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[30] );
 951
 952                 glDisable( GL_TEXTURE_2D );
 953                 glActiveTexturePtr( GL_TEXTURE1_ARB );
 954                 glDisable( GL_TEXTURE_CUBE_MAP_ARB );
 955                 glActiveTexturePtr( GL_TEXTURE2_ARB );
 956                 glDisable( GL_TEXTURE_2D );
 957                 glActiveTexturePtr( GL_TEXTURE0_ARB );
 958
 959                 glDisableClientState( GL_TEXTURE_COORD_ARRAY );
 960                 glClientActiveTexturePtr( GL_TEXTURE1_ARB );
 961                 glDisableClientState( GL_TEXTURE_COORD_ARRAY );
 962                 glClientActiveTexturePtr( GL_TEXTURE2_ARB );
 963                 glDisableClientState( GL_TEXTURE_COORD_ARRAY );
 964                 glClientActiveTexturePtr( GL_TEXTURE0_ARB );
 965
 966                 glDisableClientState( GL_COLOR_ARRAY );
 967                 glEnable( GL_LIGHTING );
 968
 969                 glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
 970
 971             } else {
 972                 glClientActiveTexturePtr( GL_TEXTURE0_ARB );
 973                 glActiveTexturePtr( GL_TEXTURE0_ARB );
 974
 975                 //Draw cloud layer
 976                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[0] );
 977                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[10] );
 978                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[20] );
 979                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[30] );
 980
 981                 //Disable textures
 982                 glDisable( GL_TEXTURE_2D );
 983
 984                 glActiveTexturePtr( GL_TEXTURE1_ARB );
 985                 glDisable( GL_TEXTURE_CUBE_MAP_ARB );
 986                 glActiveTexturePtr( GL_TEXTURE0_ARB );
 987
 988                 //disable vertex arrays
 989                 glDisableClientState( GL_VERTEX_ARRAY );
 990
 991                 glDisableClientState( GL_TEXTURE_COORD_ARRAY );
 992                 glClientActiveTexturePtr( GL_TEXTURE1_ARB );
 993                 glDisableClientState( GL_TEXTURE_COORD_ARRAY );
 994                 glClientActiveTexturePtr( GL_TEXTURE0_ARB );
 995
 996                 //Return to standard modulate texenv
 997                 glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
 998
 999                 glDepthFunc(GL_LEQUAL);
1000
1001                 glEnable( GL_LIGHTING );
1002                 sgVec4 color;
1003                 ssgGetLight( 0 )->getColour( GL_DIFFUSE, color );
1004                 float average = ( color[0] + color[1] + color[2] ) / 3.0f;
1005                 sgVec4 averageColor;
1006                 sgSetVec4( averageColor, average, average, average, 1.0f );
1007                 ssgGetLight( 0 )->setColour( GL_DIFFUSE, averageColor );
1008
1009                 glBlendColorPtr( average, average, average, 1.0f );
1010                 glBlendFunc( GL_ONE_MINUS_CONSTANT_COLOR, GL_CONSTANT_COLOR );
1011
1012                 //Perform a second pass to color the torus
1013                 //Bind decal texture
1014                 glBindTexture( GL_TEXTURE_2D, decal->getHandle() );
1015                 glEnable(GL_TEXTURE_2D);
1016
1017                 //Set vertex arrays for torus
1018                 glVertexPointer( 3, GL_FLOAT, sizeof(CloudVertex), &vertices[0].position );
1019                 glEnableClientState( GL_VERTEX_ARRAY );
1020
1021                 //glColorPointer( 4, GL_FLOAT, sizeof(CloudVertex), &vertices[0].color );
1022                 //glEnableClientState( GL_COLOR_ARRAY );
1023
1024                 glNormalPointer( GL_FLOAT, sizeof(CloudVertex), &vertices[0].normal );
1025                 glEnableClientState( GL_NORMAL_ARRAY );
1026
1027                 glTexCoordPointer( 2, GL_FLOAT, sizeof(CloudVertex), &vertices[0].texCoord );
1028                 glEnableClientState( GL_TEXTURE_COORD_ARRAY );
1029
1030                 //Draw cloud layer
1031                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[0] );
1032                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[10] );
1033                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[20] );
1034                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[30] );
1035
1036                 ssgGetLight( 0 )->setColour( GL_DIFFUSE, color );
1037
1038                 glDisableClientState( GL_TEXTURE_COORD_ARRAY );
1039             }
1040             //Disable texture
1041             glDisable( GL_TEXTURE_2D );
1042
1043             glDisableClientState( GL_VERTEX_ARRAY );
1044             glDisableClientState( GL_NORMAL_ARRAY );
1045
1046             glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
1047             glEnable( GL_CULL_FACE );
1048             glDepthFunc(GL_LESS);
1049
1050             ssgLoadModelviewMatrix( modelview );
1051
1052         } else {
1053             state_sel->selectStep( top ? 1 : 0 );
1054             ssgCullAndDraw( layer_root );
1055         }
1056     }
1057 }
1058
1059
1060 // make an ssgSimpleState for a cloud layer given the named texture
1061 ssgSimpleState *sgCloudMakeState( const string &path ) {
1062     ssgSimpleState *state = new ssgSimpleState();
1063
1064     SG_LOG(SG_ASTRO, SG_INFO, " texture = ");
1065
1066     state->setTexture( (char *)path.c_str() );
1067     state->setShadeModel( GL_SMOOTH );
1068     state->disable( GL_LIGHTING );
1069     state->disable( GL_CULL_FACE );
1070     state->enable( GL_TEXTURE_2D );
1071     state->enable( GL_COLOR_MATERIAL );
1072     state->setColourMaterial( GL_AMBIENT_AND_DIFFUSE );
1073     state->setMaterial( GL_EMISSION, 0.05, 0.05, 0.05, 0.0 );
1074     state->setMaterial( GL_AMBIENT, 0.2, 0.2, 0.2, 0.0 );
1075     state->setMaterial( GL_DIFFUSE, 0.5, 0.5, 0.5, 0.0 );
1076     state->setMaterial( GL_SPECULAR, 0.0, 0.0, 0.0, 0.0 );
1077     state->enable( GL_BLEND );
1078     state->enable( GL_ALPHA_TEST );
1079     state->setAlphaClamp( 0.01 );
1080
1081     return state;
1082 }