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  - http://www.flightgear.org/~curt
   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 <plib/sg.h>
  32 #include <plib/ssg.h>
  33
  34 #include <simgear/math/point3d.hxx>
  35 #include <simgear/math/polar3d.hxx>
  36 #include <simgear/math/sg_random.h>
  37 #include <simgear/debug/logstream.hxx>
  38 #include <simgear/misc/sg_path.hxx>
  39 #include <simgear/screen/extensions.hxx>
  40 #include <simgear/screen/texture.hxx>
  41
  42 #include "cloud.hxx"
  43
  44 #if defined(__MINGW32__)
  45 #define isnan(x) _isnan(x)
  46 #endif
  47
  48 #if defined (__FreeBSD__)
  49 inline int isnan(double r) { return !(r < 0 || r > 0); }
  50 #endif
  51
  52
  53
  54 static ssgStateSelector *layer_states[SGCloudLayer::SG_MAX_CLOUD_COVERAGES];
  55 static bool state_initialized = false;
  56 static bool bump_mapping = false;
  57 static int nb_texture_unit = 0;
  58 static ssgTexture *normal_map[SGCloudLayer::SG_MAX_CLOUD_COVERAGES][2] = { 0 };
  59 static ssgTexture *color_map[SGCloudLayer::SG_MAX_CLOUD_COVERAGES][2] = { 0 };
  60 static GLuint normalization_cube_map;
  61
  62 static glActiveTextureProc glActiveTexturePtr = 0;
  63 static glClientActiveTextureProc glClientActiveTexturePtr = 0;
  64 static glBlendColorProc glBlendColorPtr = 0;
  65
  66 bool SGCloudLayer::enable_bump_mapping = false;
  67
  68 static void
  69 generateNormalizationCubeMap()
  70 {
  71     unsigned char data[ 32 * 32 * 3 ];
  72     const int size = 32;
  73     const float half_size = 16.0f,
  74                 offset = 0.5f;
  75     sgVec3 zero_normal;
  76     sgSetVec3( zero_normal, 0.5f, 0.5f, 0.5f );
  77     int i, j;
  78
  79     unsigned char *ptr = data;
  80     for ( j = 0; j < size; j++ ) {
  81         for ( i = 0; i < size; i++ ) {
  82             sgVec3 tmp;
  83             sgSetVec3( tmp, half_size,
  84                             -( j + offset - half_size ),
  85                             -( i + offset - half_size ) );
  86             sgNormalizeVec3( tmp );
  87             sgScaleVec3( tmp, 0.5f );
  88             sgAddVec3( tmp, zero_normal );
  89
  90             *ptr++ = (unsigned char)( tmp[ 0 ] * 255 );
  91             *ptr++ = (unsigned char)( tmp[ 1 ] * 255 );
  92             *ptr++ = (unsigned char)( tmp[ 2 ] * 255 );
  93         }
  94     }
  95     glTexImage2D( GL_TEXTURE_CUBE_MAP_POSITIVE_X_ARB,
  96                   0, GL_RGBA8, 32, 32, 0, GL_RGB, GL_UNSIGNED_BYTE, data );
  97
  98     ptr = data;
  99     for ( j = 0; j < size; j++ ) {
 100         for ( i = 0; i < size; i++ ) {
 101             sgVec3 tmp;
 102             sgSetVec3( tmp, -half_size,
 103                             -( j + offset - half_size ),
 104                             ( i + offset - half_size ) );
 105             sgNormalizeVec3( tmp );
 106             sgScaleVec3( tmp, 0.5f );
 107             sgAddVec3( tmp, zero_normal );
 108
 109             *ptr++ = (unsigned char)( tmp[ 0 ] * 255 );
 110             *ptr++ = (unsigned char)( tmp[ 1 ] * 255 );
 111             *ptr++ = (unsigned char)( tmp[ 2 ] * 255 );
 112         }
 113     }
 114     glTexImage2D( GL_TEXTURE_CUBE_MAP_NEGATIVE_X_ARB,
 115                   0, GL_RGBA8, 32, 32, 0, GL_RGB, GL_UNSIGNED_BYTE, data );
 116
 117     ptr = data;
 118     for ( j = 0; j < size; j++ ) {
 119         for ( i = 0; i < size; i++ ) {
 120             sgVec3 tmp;
 121             sgSetVec3( tmp, ( i + offset - half_size ),
 122                             half_size,
 123                             ( j + offset - half_size ) );
 124             sgNormalizeVec3( tmp );
 125             sgScaleVec3( tmp, 0.5f );
 126             sgAddVec3( tmp, zero_normal );
 127
 128             *ptr++ = (unsigned char)( tmp[ 0 ] * 255 );
 129             *ptr++ = (unsigned char)( tmp[ 1 ] * 255 );
 130             *ptr++ = (unsigned char)( tmp[ 2 ] * 255 );
 131         }
 132     }
 133     glTexImage2D( GL_TEXTURE_CUBE_MAP_POSITIVE_Y_ARB,
 134                   0, GL_RGBA8, 32, 32, 0, GL_RGB, GL_UNSIGNED_BYTE, data );
 135
 136     ptr = data;
 137     for ( j = 0; j < size; j++ ) {
 138         for ( i = 0; i < size; i++ ) {
 139             sgVec3 tmp;
 140             sgSetVec3( tmp, ( i + offset - half_size ),
 141                             -half_size,
 142                             -( j + offset - half_size ) );
 143             sgNormalizeVec3( tmp );
 144             sgScaleVec3( tmp, 0.5f );
 145             sgAddVec3( tmp, zero_normal );
 146
 147             *ptr++ = (unsigned char)( tmp[ 0 ] * 255 );
 148             *ptr++ = (unsigned char)( tmp[ 1 ] * 255 );
 149             *ptr++ = (unsigned char)( tmp[ 2 ] * 255 );
 150         }
 151     }
 152     glTexImage2D( GL_TEXTURE_CUBE_MAP_NEGATIVE_Y_ARB,
 153                   0, GL_RGBA8, 32, 32, 0, GL_RGB, GL_UNSIGNED_BYTE, data );
 154
 155     ptr = data;
 156     for ( j = 0; j < size; j++ ) {
 157         for ( i = 0; i < size; i++ ) {
 158             sgVec3 tmp;
 159             sgSetVec3( tmp, ( i + offset - half_size ),
 160                             -( j + offset - half_size ),
 161                             half_size );
 162             sgNormalizeVec3( tmp );
 163             sgScaleVec3( tmp, 0.5f );
 164             sgAddVec3( tmp, zero_normal );
 165
 166             *ptr++ = (unsigned char)( tmp[ 0 ] * 255 );
 167             *ptr++ = (unsigned char)( tmp[ 1 ] * 255 );
 168             *ptr++ = (unsigned char)( tmp[ 2 ] * 255 );
 169         }
 170     }
 171     glTexImage2D( GL_TEXTURE_CUBE_MAP_POSITIVE_Z_ARB,
 172                   0, GL_RGBA8, 32, 32, 0, GL_RGB, GL_UNSIGNED_BYTE, data );
 173
 174     ptr = data;
 175     for ( j = 0; j < size; j++ ) {
 176         for ( i = 0; i < size; i++ ) {
 177             sgVec3 tmp;
 178             sgSetVec3( tmp, -( i + offset - half_size ),
 179                             -( j + offset - half_size ),
 180                             -half_size );
 181             sgNormalizeVec3( tmp );
 182             sgScaleVec3( tmp, 0.5f );
 183             sgAddVec3( tmp, zero_normal );
 184
 185             *ptr++ = (unsigned char)( tmp[ 0 ] * 255 );
 186             *ptr++ = (unsigned char)( tmp[ 1 ] * 255 );
 187             *ptr++ = (unsigned char)( tmp[ 2 ] * 255 );
 188         }
 189     }
 190     glTexImage2D( GL_TEXTURE_CUBE_MAP_NEGATIVE_Z_ARB,
 191                   0, GL_RGBA8, 32, 32, 0, GL_RGB, GL_UNSIGNED_BYTE, data );
 192 }
 193
 194
 195 // Constructor
 196 SGCloudLayer::SGCloudLayer( const string &tex_path ) :
 197     layer_root(new ssgRoot),
 198     layer_transform(new ssgTransform),
 199     state_sel(0),
 200     texture_path(tex_path),
 201     layer_span(0.0),
 202     layer_asl(0.0),
 203     layer_thickness(0.0),
 204     layer_transition(0.0),
 205     layer_coverage(SG_CLOUD_CLEAR),
 206     scale(4000.0),
 207     speed(0.0),
 208     direction(0.0),
 209     last_lon(0.0),
 210     last_lat(0.0),
 211     vertices(0),
 212     indices(0)
 213 {
 214     cl[0] = cl[1] = cl[2] = cl[3] = NULL;
 215     vl[0] = vl[1] = vl[2] = vl[3] = NULL;
 216     tl[0] = tl[1] = tl[2] = tl[3] = NULL;
 217     layer[0] = layer[1] = layer[2] = layer[3] = NULL;
 218
 219     layer_root->addKid(layer_transform);
 220     rebuild();
 221 }
 222
 223 // Destructor
 224 SGCloudLayer::~SGCloudLayer()
 225 {
 226     delete vertices;
 227     delete indices;
 228     delete layer_root;          // deletes layer_transform and layer as well
 229 }
 230
 231 float
 232 SGCloudLayer::getSpan_m () const
 233 {
 234     return layer_span;
 235 }
 236
 237 void
 238 SGCloudLayer::setSpan_m (float span_m)
 239 {
 240     if (span_m != layer_span) {
 241         layer_span = span_m;
 242         rebuild();
 243     }
 244 }
 245
 246 float
 247 SGCloudLayer::getElevation_m () const
 248 {
 249     return layer_asl;
 250 }
 251
 252 void
 253 SGCloudLayer::setElevation_m (float elevation_m, bool set_span)
 254 {
 255     layer_asl = elevation_m;
 256
 257     if (set_span) {
 258         if (elevation_m > 4000)
 259             setSpan_m(  elevation_m * 10 );
 260         else
 261             setSpan_m( 40000 );
 262     }
 263 }
 264
 265 float
 266 SGCloudLayer::getThickness_m () const
 267 {
 268     return layer_thickness;
 269 }
 270
 271 void
 272 SGCloudLayer::setThickness_m (float thickness_m)
 273 {
 274     layer_thickness = thickness_m;
 275 }
 276
 277 float
 278 SGCloudLayer::getTransition_m () const
 279 {
 280     return layer_transition;
 281 }
 282
 283 void
 284 SGCloudLayer::setTransition_m (float transition_m)
 285 {
 286     layer_transition = transition_m;
 287 }
 288
 289 SGCloudLayer::Coverage
 290 SGCloudLayer::getCoverage () const
 291 {
 292     return layer_coverage;
 293 }
 294
 295 void
 296 SGCloudLayer::setCoverage (Coverage coverage)
 297 {
 298     if (coverage != layer_coverage) {
 299         layer_coverage = coverage;
 300         rebuild();
 301     }
 302 }
 303
 304
 305 // build the cloud object
 306 void
 307 SGCloudLayer::rebuild()
 308 {
 309     // Initialize states and sizes if necessary.
 310     if ( !state_initialized ) {
 311         state_initialized = true;
 312
 313         SG_LOG(SG_ASTRO, SG_INFO, "initializing cloud layers");
 314
 315         bump_mapping = SGIsOpenGLExtensionSupported("GL_ARB_multitexture") &&
 316                        SGIsOpenGLExtensionSupported("GL_ARB_texture_cube_map") &&
 317                        SGIsOpenGLExtensionSupported("GL_ARB_texture_env_combine") &&
 318                        SGIsOpenGLExtensionSupported("GL_ARB_texture_env_dot3") &&
 319                        SGIsOpenGLExtensionSupported("GL_ARB_imaging");
 320
 321         if ( bump_mapping ) {
 322             glGetIntegerv( GL_MAX_TEXTURE_UNITS_ARB, &nb_texture_unit );
 323             if ( nb_texture_unit < 2 ) {
 324                 bump_mapping = false;
 325             }
 326             //nb_texture_unit = 2; // Force the number of units for now
 327         }
 328
 329         if ( bump_mapping ) {
 330
 331             // This bump mapping code was inspired by the tutorial available at
 332             // http://www.paulsprojects.net/tutorials/simplebump/simplebump.html
 333             // and a NVidia white paper
 334             //  http://developer.nvidia.com/object/bumpmappingwithregistercombiners.html
 335             // The normal map textures were generated by the normal map Gimp plugin :
 336             //  http://nifelheim.dyndns.org/~cocidius/normalmap/
 337             //
 338             SGPath cloud_path;
 339
 340             glActiveTexturePtr = (glActiveTextureProc)SGLookupFunction("glActiveTextureARB");
 341             glClientActiveTexturePtr = (glClientActiveTextureProc)SGLookupFunction("glClientActiveTextureARB");
 342             glBlendColorPtr = (glBlendColorProc)SGLookupFunction("glBlendColor");
 343
 344             cloud_path.set(texture_path.str());
 345             cloud_path.append("overcast.rgb");
 346             color_map[ SG_CLOUD_OVERCAST ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 347             color_map[ SG_CLOUD_OVERCAST ][ 0 ]->ref();
 348             cloud_path.set(texture_path.str());
 349             cloud_path.append("overcast_n.rgb");
 350             normal_map[ SG_CLOUD_OVERCAST ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 351             normal_map[ SG_CLOUD_OVERCAST ][ 0 ]->ref();
 352
 353             cloud_path.set(texture_path.str());
 354             cloud_path.append("overcast_top.rgb");
 355             color_map[ SG_CLOUD_OVERCAST ][ 1 ] = new ssgTexture( cloud_path.str().c_str() );
 356             color_map[ SG_CLOUD_OVERCAST ][ 1 ]->ref();
 357             cloud_path.set(texture_path.str());
 358             cloud_path.append("overcast_top_n.rgb");
 359             normal_map[ SG_CLOUD_OVERCAST ][ 1 ] = new ssgTexture( cloud_path.str().c_str() );
 360             normal_map[ SG_CLOUD_OVERCAST ][ 1 ]->ref();
 361
 362             cloud_path.set(texture_path.str());
 363             cloud_path.append("broken.rgba");
 364             color_map[ SG_CLOUD_BROKEN ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 365             color_map[ SG_CLOUD_BROKEN ][ 0 ]->ref();
 366             cloud_path.set(texture_path.str());
 367             cloud_path.append("broken_n.rgb");
 368             normal_map[ SG_CLOUD_BROKEN ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 369             normal_map[ SG_CLOUD_BROKEN ][ 0 ]->ref();
 370
 371             cloud_path.set(texture_path.str());
 372             cloud_path.append("scattered.rgba");
 373             color_map[ SG_CLOUD_SCATTERED ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 374             color_map[ SG_CLOUD_SCATTERED ][ 0 ]->ref();
 375             cloud_path.set(texture_path.str());
 376             cloud_path.append("scattered_n.rgb");
 377             normal_map[ SG_CLOUD_SCATTERED ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 378             normal_map[ SG_CLOUD_SCATTERED ][ 0 ]->ref();
 379
 380             cloud_path.set(texture_path.str());
 381             cloud_path.append("few.rgba");
 382             color_map[ SG_CLOUD_FEW ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 383             color_map[ SG_CLOUD_FEW ][ 0 ]->ref();
 384             cloud_path.set(texture_path.str());
 385             cloud_path.append("few_n.rgb");
 386             normal_map[ SG_CLOUD_FEW ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 387             normal_map[ SG_CLOUD_FEW ][ 0 ]->ref();
 388
 389             cloud_path.set(texture_path.str());
 390             cloud_path.append("cirrus.rgba");
 391             color_map[ SG_CLOUD_CIRRUS ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 392             color_map[ SG_CLOUD_CIRRUS ][ 0 ]->ref();
 393             cloud_path.set(texture_path.str());
 394             cloud_path.append("cirrus_n.rgb");
 395             normal_map[ SG_CLOUD_CIRRUS ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 396             normal_map[ SG_CLOUD_CIRRUS ][ 0 ]->ref();
 397
 398             glGenTextures( 1, &normalization_cube_map );
 399             glBindTexture( GL_TEXTURE_CUBE_MAP_ARB, normalization_cube_map );
 400             generateNormalizationCubeMap();
 401             glTexParameteri( GL_TEXTURE_CUBE_MAP_ARB, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
 402             glTexParameteri( GL_TEXTURE_CUBE_MAP_ARB, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
 403             glTexParameteri( GL_TEXTURE_CUBE_MAP_ARB, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );
 404             glTexParameteri( GL_TEXTURE_CUBE_MAP_ARB, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE );
 405             glTexParameteri( GL_TEXTURE_CUBE_MAP_ARB, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE );
 406         } /* else */ {
 407             SGPath cloud_path;
 408             ssgStateSelector *state_sel;
 409             ssgSimpleState *state;
 410
 411             state_sel = new ssgStateSelector( 2 );
 412             state_sel->ref();
 413             cloud_path.set(texture_path.str());
 414             cloud_path.append("overcast.rgb");
 415             state_sel->setStep( 0, sgCloudMakeState(cloud_path.str()) );
 416             cloud_path.set(texture_path.str());
 417             cloud_path.append("overcast_top.rgb");
 418             state_sel->setStep( 1, sgCloudMakeState(cloud_path.str()) );
 419             layer_states[SG_CLOUD_OVERCAST] = state_sel;
 420
 421             state_sel = new ssgStateSelector( 2 );
 422             state_sel->ref();
 423             cloud_path.set(texture_path.str());
 424             cloud_path.append("broken.rgba");
 425             state = sgCloudMakeState(cloud_path.str());
 426             state_sel->setStep( 0, state );
 427             state_sel->setStep( 1, state );
 428             layer_states[SG_CLOUD_BROKEN] = state_sel;
 429
 430             state_sel = new ssgStateSelector( 2 );
 431             state_sel->ref();
 432             cloud_path.set(texture_path.str());
 433             cloud_path.append("scattered.rgba");
 434             state = sgCloudMakeState(cloud_path.str());
 435             state_sel->setStep( 0, state );
 436             state_sel->setStep( 1, state );
 437             layer_states[SG_CLOUD_SCATTERED] = state_sel;
 438
 439             state_sel = new ssgStateSelector( 2 );
 440             state_sel->ref();
 441             cloud_path.set(texture_path.str());
 442             cloud_path.append("few.rgba");
 443             state = sgCloudMakeState(cloud_path.str());
 444             state_sel->setStep( 0, state );
 445             state_sel->setStep( 1, state );
 446             layer_states[SG_CLOUD_FEW] = state_sel;
 447
 448             state_sel = new ssgStateSelector( 2 );
 449             state_sel->ref();
 450             cloud_path.set(texture_path.str());
 451             cloud_path.append("cirrus.rgba");
 452             state = sgCloudMakeState(cloud_path.str());
 453             state_sel->setStep( 0, state );
 454             state_sel->setStep( 1, state );
 455             layer_states[SG_CLOUD_CIRRUS] = state_sel;
 456
 457             layer_states[SG_CLOUD_CLEAR] = 0;
 458         }
 459     }
 460
 461     if ( bump_mapping ) {
 462
 463         if ( !vertices ) {
 464             vertices = new CloudVertex[ 25 ];
 465             indices = new unsigned int[ 40 ];
 466         }
 467
 468         sgVec2 base;
 469         sgSetVec2( base, sg_random(), sg_random() );
 470
 471         const float layer_scale = layer_span / scale;
 472         const float layer_to_core = (SG_EARTH_RAD * 1000 + layer_asl);
 473         const float half_angle = 0.5 * layer_span / layer_to_core;
 474
 475         int i;
 476         for ( i = -2; i <= 2; i++ ) {
 477             for ( int j = -2; j <= 2; j++ ) {
 478                 CloudVertex &v1 = vertices[ (i+2)*5 + (j+2) ];
 479                 sgSetVec3( v1.position,
 480                            0.5 * i * layer_span,
 481                            0.5 * j * layer_span,
 482                            -layer_to_core * ( 1 - cos( i * half_angle ) * cos( j * half_angle ) ) );
 483                 sgSetVec2( v1.texCoord,
 484                            base[0] + layer_scale * i * 0.25,
 485                            base[1] + layer_scale * j * 0.25 );
 486                 sgSetVec3( v1.sTangent,
 487                            cos( i * half_angle ),
 488                            0.f,
 489                            -sin( i * half_angle ) );
 490                 sgSetVec3( v1.tTangent,
 491                            0.f,
 492                            cos( j * half_angle ),
 493                            -sin( j * half_angle ) );
 494                 sgVectorProductVec3( v1.normal, v1.tTangent, v1.sTangent );
 495                 sgSetVec4( v1.color, 1.0f, 1.0f, 1.0f, (i == 0) ? 0.0f : 0.15f );
 496             }
 497         }
 498         /*
 499          * 0 1 5 6 10 11 15 16 20 21
 500          * 1 2 6 7 11 12 16 17 21 22
 501          * 2 3 7 8 12 13 17 18 22 23
 502          * 3 4 8 9 13 14 18 19 23 24
 503          */
 504         for ( i = 0; i < 4; i++ ) {
 505             for ( int j = 0; j < 5; j++ ) {
 506                 indices[ i*10 + (j*2) ]     =     i + 5 * j;
 507                 indices[ i*10 + (j*2) + 1 ] = 1 + i + 5 * j;
 508             }
 509         }
 510
 511     } /* else */ {
 512
 513         scale = 4000.0;
 514         last_lon = last_lat = -999.0f;
 515
 516         sgVec2 base;
 517         sgSetVec2( base, sg_random(), sg_random() );
 518
 519         // build the cloud layer
 520         sgVec4 color;
 521         sgVec3 vertex;
 522         sgVec2 tc;
 523
 524         const float layer_scale = layer_span / scale;
 525         const float mpi = SG_PI/4;
 526
 527         // caclculate the difference between a flat-earth model and
 528         // a round earth model given the span and altutude ASL of
 529         // the cloud layer. This is the difference in altitude between
 530         // the top of the inverted bowl and the edge of the bowl.
 531         // const float alt_diff = layer_asl * 0.8;
 532         const float layer_to_core = (SG_EARTH_RAD * 1000 + layer_asl);
 533         const float layer_angle = 0.5*layer_span / layer_to_core; // The angle is half the span
 534         const float border_to_core = layer_to_core * cos(layer_angle);
 535         const float alt_diff = layer_to_core - border_to_core;
 536
 537         for (int i = 0; i < 4; i++)
 538         {
 539             if ( layer[i] != NULL ) {
 540                 layer_transform->removeKid(layer[i]); // automatic delete
 541             }
 542
 543             vl[i] = new ssgVertexArray( 10 );
 544             cl[i] = new ssgColourArray( 10 );
 545             tl[i] = new ssgTexCoordArray( 10 );
 546
 547
 548             sgSetVec3( vertex, layer_span*(i-2)/2, -layer_span,
 549                             alt_diff * (sin(i*mpi) - 2) );
 550
 551             sgSetVec2( tc, base[0] + layer_scale * i/4, base[1] );
 552
 553             sgSetVec4( color, 1.0f, 1.0f, 1.0f, (i == 0) ? 0.0f : 0.15f );
 554
 555             cl[i]->add( color );
 556             vl[i]->add( vertex );
 557             tl[i]->add( tc );
 558
 559             for (int j = 0; j < 4; j++)
 560             {
 561                 sgSetVec3( vertex, layer_span*(i-1)/2, layer_span*(j-2)/2,
 562                                 alt_diff * (sin((i+1)*mpi) + sin(j*mpi) - 2) );
 563
 564                 sgSetVec2( tc, base[0] + layer_scale * (i+1)/4,
 565                             base[1] + layer_scale * j/4 );
 566
 567                 sgSetVec4( color, 1.0f, 1.0f, 1.0f,
 568                                 ( (j == 0) || (i == 3)) ?
 569                                 ( (j == 0) && (i == 3)) ? 0.0f : 0.15f : 1.0f );
 570
 571                 cl[i]->add( color );
 572                 vl[i]->add( vertex );
 573                 tl[i]->add( tc );
 574
 575
 576                 sgSetVec3( vertex, layer_span*(i-2)/2, layer_span*(j-1)/2,
 577                                 alt_diff * (sin(i*mpi) + sin((j+1)*mpi) - 2) );
 578
 579                 sgSetVec2( tc, base[0] + layer_scale * i/4,
 580                             base[1] + layer_scale * (j+1)/4 );
 581
 582                 sgSetVec4( color, 1.0f, 1.0f, 1.0f,
 583                                 ((j == 3) || (i == 0)) ?
 584                                 ((j == 3) && (i == 0)) ? 0.0f : 0.15f : 1.0f );
 585                 cl[i]->add( color );
 586                 vl[i]->add( vertex );
 587                 tl[i]->add( tc );
 588             }
 589
 590             sgSetVec3( vertex, layer_span*(i-1)/2, layer_span,
 591                             alt_diff * (sin((i+1)*mpi) - 2) );
 592
 593             sgSetVec2( tc, base[0] + layer_scale * (i+1)/4,
 594                         base[1] + layer_scale );
 595
 596             sgSetVec4( color, 1.0f, 1.0f, 1.0f, (i == 3) ? 0.0f : 0.15f );
 597
 598             cl[i]->add( color );
 599             vl[i]->add( vertex );
 600             tl[i]->add( tc );
 601
 602             layer[i] = new ssgVtxTable(GL_TRIANGLE_STRIP, vl[i], NULL, tl[i], cl[i]);
 603             layer_transform->addKid( layer[i] );
 604
 605             if ( layer_states[layer_coverage] != NULL ) {
 606                 layer[i]->setState( layer_states[layer_coverage] );
 607             }
 608             state_sel = layer_states[layer_coverage];
 609         }
 610
 611         // force a repaint of the sky colors with arbitrary defaults
 612         repaint( color );
 613     }
 614 }
 615
 616
 617 // repaint the cloud layer colors
 618 bool SGCloudLayer::repaint( sgVec3 fog_color ) {
 619
 620     if ( bump_mapping && enable_bump_mapping ) {
 621
 622         for ( int i = 0; i < 25; i++ ) {
 623             sgCopyVec3( vertices[ i ].color, fog_color );
 624         }
 625
 626     } else {
 627         float *color;
 628
 629         for ( int i = 0; i < 4; i++ ) {
 630             for ( int j = 0; j < 10; ++j ) {
 631                 color = cl[i]->get( j );
 632                 sgCopyVec3( color, fog_color );
 633             }
 634         }
 635     }
 636
 637     return true;
 638 }
 639
 640 // reposition the cloud layer at the specified origin and orientation
 641 // lon specifies a rotation about the Z axis
 642 // lat specifies a rotation about the new Y axis
 643 // spin specifies a rotation about the new Z axis (and orients the
 644 // sunrise/set effects
 645 bool SGCloudLayer::reposition( sgVec3 p, sgVec3 up, double lon, double lat,
 646                                double alt, double dt )
 647 {
 648     sgMat4 T1, LON, LAT;
 649     sgVec3 axis;
 650
 651     // combine p and asl (meters) to get translation offset
 652     sgVec3 asl_offset;
 653     sgCopyVec3( asl_offset, up );
 654     sgNormalizeVec3( asl_offset );
 655     if ( alt <= layer_asl ) {
 656         sgScaleVec3( asl_offset, layer_asl );
 657     } else {
 658         sgScaleVec3( asl_offset, layer_asl + layer_thickness );
 659     }
 660     // cout << "asl_offset = " << asl_offset[0] << "," << asl_offset[1]
 661     //      << "," << asl_offset[2] << endl;
 662     sgAddVec3( asl_offset, p );
 663     // cout << "  asl_offset = " << asl_offset[0] << "," << asl_offset[1]
 664     //      << "," << asl_offset[2] << endl;
 665
 666     // Translate to zero elevation
 667     // Point3D zero_elev = current_view.get_cur_zero_elev();
 668     sgMakeTransMat4( T1, asl_offset );
 669
 670     // printf("  Translated to %.2f %.2f %.2f\n",
 671     //        zero_elev.x, zero_elev.y, zero_elev.z );
 672
 673     // Rotate to proper orientation
 674     // printf("  lon = %.2f  lat = %.2f\n",
 675     //        lon * SGD_RADIANS_TO_DEGREES,
 676     //        lat * SGD_RADIANS_TO_DEGREES);
 677     sgSetVec3( axis, 0.0, 0.0, 1.0 );
 678     sgMakeRotMat4( LON, lon * SGD_RADIANS_TO_DEGREES, axis );
 679
 680     sgSetVec3( axis, 0.0, 1.0, 0.0 );
 681     sgMakeRotMat4( LAT, 90.0 - lat * SGD_RADIANS_TO_DEGREES, axis );
 682
 683     sgMat4 TRANSFORM;
 684
 685     sgCopyMat4( TRANSFORM, T1 );
 686     sgPreMultMat4( TRANSFORM, LON );
 687     sgPreMultMat4( TRANSFORM, LAT );
 688
 689     sgCoord layerpos;
 690     sgSetCoord( &layerpos, TRANSFORM );
 691
 692     layer_transform->setTransform( &layerpos );
 693
 694     // now calculate update texture coordinates
 695     if ( last_lon < -900 ) {
 696         last_lon = lon;
 697         last_lat = lat;
 698     }
 699
 700     double sp_dist = speed*dt;
 701
 702     if ( lon != last_lon || lat != last_lat || sp_dist != 0 ) {
 703         Point3D start( last_lon, last_lat, 0.0 );
 704         Point3D dest( lon, lat, 0.0 );
 705         double course = 0.0, dist = 0.0;
 706
 707         calc_gc_course_dist( dest, start, &course, &dist );
 708         // cout << "course = " << course << ", dist = " << dist << endl;
 709
 710         // if start and dest are too close together,
 711         // calc_gc_course_dist() can return a course of "nan".  If
 712         // this happens, lets just use the last known good course.
 713         // This is a hack, and it would probably be better to make
 714         // calc_gc_course_dist() more robust.
 715         if ( isnan(course) ) {
 716             course = last_course;
 717         } else {
 718             last_course = course;
 719         }
 720
 721         // calculate cloud movement due to external forces
 722         double ax = 0.0, ay = 0.0, bx = 0.0, by = 0.0;
 723
 724         if (dist > 0.0) {
 725             ax = cos(course) * dist;
 726             ay = sin(course) * dist;
 727         }
 728
 729         if (sp_dist > 0) {
 730             bx = cos((180.0-direction) * SGD_DEGREES_TO_RADIANS) * sp_dist;
 731             by = sin((180.0-direction) * SGD_DEGREES_TO_RADIANS) * sp_dist;
 732         }
 733
 734
 735         double xoff = (ax + bx) / (2 * scale);
 736         double yoff = (ay + by) / (2 * scale);
 737
 738         const float layer_scale = layer_span / scale;
 739
 740         // cout << "xoff = " << xoff << ", yoff = " << yoff << endl;
 741
 742         float *base;
 743         if ( bump_mapping && enable_bump_mapping ) {
 744             base = vertices[12].texCoord;
 745         } else {
 746             base = tl[0]->get( 0 );
 747         }
 748         base[0] += xoff;
 749
 750         // the while loops can lead to *long* pauses if base[0] comes
 751         // with a bogus value.
 752         // while ( base[0] > 1.0 ) { base[0] -= 1.0; }
 753         // while ( base[0] < 0.0 ) { base[0] += 1.0; }
 754         if ( base[0] > -10.0 && base[0] < 10.0 ) {
 755             base[0] -= (int)base[0];
 756         } else {
 757             SG_LOG(SG_ASTRO, SG_DEBUG,
 758                 "Error: base = " << base[0] << "," << base[1] <<
 759                 " course = " << course << " dist = " << dist );
 760             base[0] = 0.0;
 761         }
 762
 763         base[1] += yoff;
 764         // the while loops can lead to *long* pauses if base[0] comes
 765         // with a bogus value.
 766         // while ( base[1] > 1.0 ) { base[1] -= 1.0; }
 767         // while ( base[1] < 0.0 ) { base[1] += 1.0; }
 768         if ( base[1] > -10.0 && base[1] < 10.0 ) {
 769             base[1] -= (int)base[1];
 770         } else {
 771             SG_LOG(SG_ASTRO, SG_ALERT,
 772                     "Error: base = " << base[0] << "," << base[1] <<
 773                     " course = " << course << " dist = " << dist );
 774             base[1] = 0.0;
 775         }
 776
 777         if ( bump_mapping && enable_bump_mapping ) {
 778
 779             for ( int i = -2; i <= 2; i++ ) {
 780                 for ( int j = -2; j <= 2; j++ ) {
 781                     if ( i == 0 && j == 0 )
 782                         continue; // Already done on base
 783                     CloudVertex &v1 = vertices[ (i+2)*5 + (j+2) ];
 784                     sgSetVec2( v1.texCoord,
 785                             base[0] + layer_scale * i * 0.25,
 786                             base[1] + layer_scale * j * 0.25 );
 787                 }
 788             }
 789
 790         } else {
 791                 // cout << "base = " << base[0] << "," << base[1] << endl;
 792
 793             float *tc;
 794             for (int i = 0; i < 4; i++) {
 795                 tc = tl[i]->get( 0 );
 796                 sgSetVec2( tc, base[0] + layer_scale * i/4, base[1] );
 797
 798                 for (int j = 0; j < 4; j++)
 799                 {
 800                     tc = tl[i]->get( j*2+1 );
 801                     sgSetVec2( tc, base[0] + layer_scale * (i+1)/4,
 802                                 base[1] + layer_scale * j/4 );
 803
 804                     tc = tl[i]->get( (j+1)*2 );
 805                     sgSetVec2( tc, base[0] + layer_scale * i/4,
 806                                 base[1] + layer_scale * (j+1)/4 );
 807                 }
 808
 809                 tc = tl[i]->get( 9 );
 810                 sgSetVec2( tc, base[0] + layer_scale * (i+1)/4,
 811                             base[1] + layer_scale );
 812             }
 813         }
 814
 815         last_lon = lon;
 816         last_lat = lat;
 817     }
 818
 819     return true;
 820 }
 821
 822
 823 void SGCloudLayer::draw( bool top ) {
 824     if ( layer_coverage != SG_CLOUD_CLEAR ) {
 825
 826         if ( bump_mapping && enable_bump_mapping ) {
 827
 828             sgMat4 modelview,
 829                    tmp,
 830                    transform;
 831             ssgGetModelviewMatrix( modelview );
 832             layer_transform->getTransform( transform );
 833
 834             sgTransposeNegateMat4( tmp, transform );
 835
 836             sgPostMultMat4( transform, modelview );
 837             ssgLoadModelviewMatrix( transform );
 838
 839             sgVec3 lightVec;
 840             ssgGetLight( 0 )->getPosition( lightVec );
 841             sgNegateVec3( lightVec );
 842             sgXformVec3( lightVec, tmp );
 843
 844             for ( int i = 0; i < 25; i++ ) {
 845                 CloudVertex &v = vertices[ i ];
 846                 sgSetVec3( v.tangentSpLight,
 847                            sgScalarProductVec3( v.sTangent, lightVec ),
 848                            sgScalarProductVec3( v.tTangent, lightVec ),
 849                            sgScalarProductVec3( v.normal, lightVec ) );
 850             }
 851
 852             ssgTexture *decal = color_map[ layer_coverage ][ top ? 1 : 0 ];
 853             if ( top && decal == 0 ) {
 854                 decal = color_map[ layer_coverage ][ 0 ];
 855             }
 856             ssgTexture *normal = normal_map[ layer_coverage ][ top ? 1 : 0 ];
 857             if ( top && normal == 0 ) {
 858                 normal = normal_map[ layer_coverage ][ 0 ];
 859             }
 860
 861             glDisable( GL_LIGHTING );
 862             glDisable( GL_CULL_FACE );
 863 //            glDisable( GL_ALPHA_TEST );
 864             if ( layer_coverage == SG_CLOUD_FEW ) {
 865                 glEnable( GL_ALPHA_TEST );
 866                 glAlphaFunc ( GL_GREATER, 0.01 );
 867             }
 868             glEnable( GL_BLEND );
 869             glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
 870
 871             glShadeModel( GL_SMOOTH );
 872             glEnable( GL_COLOR_MATERIAL );
 873             sgVec4 color;
 874             float emis = 0.05;
 875             if ( 1 ) {
 876                 ssgGetLight( 0 )->getColour( GL_DIFFUSE, color );
 877                 emis = ( color[0]+color[1]+color[2] ) / 3.0;
 878                 if ( emis < 0.05 )
 879                     emis = 0.05;
 880             }
 881             sgSetVec4( color, emis, emis, emis, 0.0 );
 882             glMaterialfv( GL_FRONT_AND_BACK, GL_EMISSION, color );
 883             sgSetVec4( color, 1.0f, 1.0f, 1.0f, 0.0 );
 884             glMaterialfv( GL_FRONT_AND_BACK, GL_AMBIENT, color );
 885             sgSetVec4( color, 1.0, 1.0, 1.0, 0.0 );
 886             glMaterialfv( GL_FRONT_AND_BACK, GL_DIFFUSE, color );
 887             sgSetVec4( color, 0.0, 0.0, 0.0, 0.0 );
 888             glMaterialfv( GL_FRONT_AND_BACK, GL_SPECULAR, color );
 889
 890             glColor4f( 1.0f, 1.0f, 1.0f, 1.0f );
 891
 892             glActiveTexturePtr( GL_TEXTURE0_ARB );
 893             glBindTexture( GL_TEXTURE_2D, normal->getHandle() );
 894             glEnable( GL_TEXTURE_2D );
 895
 896             //Bind normalisation cube map to texture unit 1
 897             glActiveTexturePtr( GL_TEXTURE1_ARB );
 898             glBindTexture( GL_TEXTURE_CUBE_MAP_ARB, normalization_cube_map );
 899             glEnable( GL_TEXTURE_CUBE_MAP_ARB );
 900             glActiveTexturePtr( GL_TEXTURE0_ARB );
 901
 902             //Set vertex arrays for cloud
 903             glVertexPointer( 3, GL_FLOAT, sizeof(CloudVertex), &vertices[0].position );
 904             glEnableClientState( GL_VERTEX_ARRAY );
 905 /*
 906             if ( nb_texture_unit >= 3 ) {
 907                 glColorPointer( 4, GL_FLOAT, sizeof(CloudVertex), &vertices[0].color );
 908                 glEnableClientState( GL_COLOR_ARRAY );
 909             }
 910 */
 911             //Send texture coords for normal map to unit 0
 912             glTexCoordPointer( 2, GL_FLOAT, sizeof(CloudVertex), &vertices[0].texCoord );
 913             glEnableClientState( GL_TEXTURE_COORD_ARRAY );
 914
 915             //Send tangent space light vectors for normalisation to unit 1
 916             glClientActiveTexturePtr( GL_TEXTURE1_ARB );
 917             glTexCoordPointer( 3, GL_FLOAT, sizeof(CloudVertex), &vertices[0].tangentSpLight );
 918             glEnableClientState( GL_TEXTURE_COORD_ARRAY );
 919
 920             //Set up texture environment to do (tex0 dot tex1)*color
 921             glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_ARB );
 922             glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_RGB_ARB, GL_TEXTURE );
 923             glTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_RGB_ARB, GL_REPLACE );
 924             glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_ALPHA_ARB, GL_TEXTURE );
 925             glTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_ALPHA_ARB, GL_REPLACE );
 926
 927             glActiveTexturePtr( GL_TEXTURE1_ARB );
 928
 929             glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_ARB );
 930             glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_RGB_ARB, GL_TEXTURE );
 931             glTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_RGB_ARB, GL_DOT3_RGB_ARB );
 932             glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE1_RGB_ARB, GL_PREVIOUS_ARB );
 933             glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_ALPHA_ARB, GL_PREVIOUS_ARB );
 934             glTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_ALPHA_ARB, GL_REPLACE );
 935
 936             if ( nb_texture_unit >= 3 ) {
 937                 glActiveTexturePtr( GL_TEXTURE2_ARB );
 938                 glBindTexture( GL_TEXTURE_2D, decal->getHandle() );
 939
 940                 glClientActiveTexturePtr( GL_TEXTURE2_ARB );
 941                 glTexCoordPointer( 2, GL_FLOAT, sizeof(CloudVertex), &vertices[0].texCoord );
 942                 glEnableClientState( GL_TEXTURE_COORD_ARRAY );
 943
 944                 glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_ARB );
 945                 glTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_RGB_ARB, GL_ADD );
 946                 glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_RGB_ARB, GL_TEXTURE );
 947                 glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE1_RGB_ARB, GL_PREVIOUS_ARB );
 948
 949                 glClientActiveTexturePtr( GL_TEXTURE0_ARB );
 950                 glActiveTexturePtr( GL_TEXTURE0_ARB );
 951
 952                 //Draw cloud layer
 953                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[0] );
 954                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[10] );
 955                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[20] );
 956                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[30] );
 957
 958                 glDisable( GL_TEXTURE_2D );
 959                 glActiveTexturePtr( GL_TEXTURE1_ARB );
 960                 glDisable( GL_TEXTURE_CUBE_MAP_ARB );
 961                 glActiveTexturePtr( GL_TEXTURE2_ARB );
 962                 glDisable( GL_TEXTURE_2D );
 963                 glActiveTexturePtr( GL_TEXTURE0_ARB );
 964
 965                 glDisableClientState( GL_TEXTURE_COORD_ARRAY );
 966                 glClientActiveTexturePtr( GL_TEXTURE1_ARB );
 967                 glDisableClientState( GL_TEXTURE_COORD_ARRAY );
 968                 glClientActiveTexturePtr( GL_TEXTURE2_ARB );
 969                 glDisableClientState( GL_TEXTURE_COORD_ARRAY );
 970                 glClientActiveTexturePtr( GL_TEXTURE0_ARB );
 971
 972                 glDisableClientState( GL_COLOR_ARRAY );
 973                 glEnable( GL_LIGHTING );
 974
 975                 glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
 976
 977             } else {
 978                 glClientActiveTexturePtr( GL_TEXTURE0_ARB );
 979                 glActiveTexturePtr( GL_TEXTURE0_ARB );
 980
 981                 //Draw cloud layer
 982                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[0] );
 983                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[10] );
 984                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[20] );
 985                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[30] );
 986
 987                 //Disable textures
 988                 glDisable( GL_TEXTURE_2D );
 989
 990                 glActiveTexturePtr( GL_TEXTURE1_ARB );
 991                 glDisable( GL_TEXTURE_CUBE_MAP_ARB );
 992                 glActiveTexturePtr( GL_TEXTURE0_ARB );
 993
 994                 //disable vertex arrays
 995                 glDisableClientState( GL_VERTEX_ARRAY );
 996
 997                 glDisableClientState( GL_TEXTURE_COORD_ARRAY );
 998                 glClientActiveTexturePtr( GL_TEXTURE1_ARB );
 999                 glDisableClientState( GL_TEXTURE_COORD_ARRAY );
1000                 glClientActiveTexturePtr( GL_TEXTURE0_ARB );
1001
1002                 //Return to standard modulate texenv
1003                 glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
1004
1005                 if ( layer_coverage == SG_CLOUD_OVERCAST ) {
1006                     glDepthFunc(GL_LEQUAL);
1007
1008                     glEnable( GL_LIGHTING );
1009                     sgVec4 color;
1010                     ssgGetLight( 0 )->getColour( GL_DIFFUSE, color );
1011                     float average = ( color[0] + color[1] + color[2] ) / 3.0f;
1012                     average = 0.15 + average/10;
1013                     sgVec4 averageColor;
1014                     sgSetVec4( averageColor, average, average, average, 1.0f );
1015                     ssgGetLight( 0 )->setColour( GL_DIFFUSE, averageColor );
1016
1017                     glBlendColorPtr( average, average, average, 1.0f );
1018                     glBlendFunc( GL_ONE_MINUS_CONSTANT_COLOR, GL_CONSTANT_COLOR );
1019
1020                     //Perform a second pass to color the torus
1021                     //Bind decal texture
1022                     glBindTexture( GL_TEXTURE_2D, decal->getHandle() );
1023                     glEnable(GL_TEXTURE_2D);
1024
1025                     //Set vertex arrays for torus
1026                     glVertexPointer( 3, GL_FLOAT, sizeof(CloudVertex), &vertices[0].position );
1027                     glEnableClientState( GL_VERTEX_ARRAY );
1028
1029                     //glColorPointer( 4, GL_FLOAT, sizeof(CloudVertex), &vertices[0].color );
1030                     //glEnableClientState( GL_COLOR_ARRAY );
1031
1032                     glNormalPointer( GL_FLOAT, sizeof(CloudVertex), &vertices[0].normal );
1033                     glEnableClientState( GL_NORMAL_ARRAY );
1034
1035                     glTexCoordPointer( 2, GL_FLOAT, sizeof(CloudVertex), &vertices[0].texCoord );
1036                     glEnableClientState( GL_TEXTURE_COORD_ARRAY );
1037
1038                     //Draw cloud layer
1039                     glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[0] );
1040                     glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[10] );
1041                     glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[20] );
1042                     glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[30] );
1043
1044                     ssgGetLight( 0 )->setColour( GL_DIFFUSE, color );
1045
1046                     glDisableClientState( GL_TEXTURE_COORD_ARRAY );
1047                 }
1048             }
1049             //Disable texture
1050             glDisable( GL_TEXTURE_2D );
1051
1052             glDisableClientState( GL_VERTEX_ARRAY );
1053             glDisableClientState( GL_NORMAL_ARRAY );
1054
1055             glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
1056             glEnable( GL_CULL_FACE );
1057             glDepthFunc(GL_LESS);
1058
1059             ssgLoadModelviewMatrix( modelview );
1060
1061         } else {
1062             state_sel->selectStep( top ? 1 : 0 );
1063             ssgCullAndDraw( layer_root );
1064         }
1065     }
1066 }
1067
1068
1069 // make an ssgSimpleState for a cloud layer given the named texture
1070 ssgSimpleState *sgCloudMakeState( const string &path ) {
1071     ssgSimpleState *state = new ssgSimpleState();
1072
1073     SG_LOG(SG_ASTRO, SG_INFO, " texture = ");
1074
1075     state->setTexture( (char *)path.c_str() );
1076     state->setShadeModel( GL_SMOOTH );
1077     state->disable( GL_LIGHTING );
1078     state->disable( GL_CULL_FACE );
1079     state->enable( GL_TEXTURE_2D );
1080     state->enable( GL_COLOR_MATERIAL );
1081     state->setColourMaterial( GL_AMBIENT_AND_DIFFUSE );
1082     state->setMaterial( GL_EMISSION, 0.05, 0.05, 0.05, 0.0 );
1083     state->setMaterial( GL_AMBIENT, 0.2, 0.2, 0.2, 0.0 );
1084     state->setMaterial( GL_DIFFUSE, 0.5, 0.5, 0.5, 0.0 );
1085     state->setMaterial( GL_SPECULAR, 0.0, 0.0, 0.0, 0.0 );
1086     state->enable( GL_BLEND );
1087     state->enable( GL_ALPHA_TEST );
1088     state->setAlphaClamp( 0.01 );
1089
1090     return state;
1091 }