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 (isnan)(double r) { return isnan(r); }
  28 // #endif
  29
  30 #if defined(__MINGW32__)
  31 #define isnan(x) _isnan(x)
  32 #endif
  33
  34 // #include STL_IOSTREAM
  35
  36 #include <plib/sg.h>
  37 #include <plib/ssg.h>
  38
  39 #include <simgear/math/point3d.hxx>
  40 #include <simgear/math/polar3d.hxx>
  41 #include <simgear/math/sg_random.h>
  42 #include <simgear/debug/logstream.hxx>
  43 #include <simgear/misc/sg_path.hxx>
  44 #include <simgear/screen/extensions.hxx>
  45 #include <simgear/screen/texture.hxx>
  46
  47 #include "cloud.hxx"
  48
  49
  50 static ssgStateSelector *layer_states[SGCloudLayer::SG_MAX_CLOUD_COVERAGES];
  51 static bool state_initialized = false;
  52 static bool bump_mapping = false;
  53 static int nb_texture_unit = 0;
  54 static ssgTexture *normal_map[SGCloudLayer::SG_MAX_CLOUD_COVERAGES][2] = { 0 };
  55 static ssgTexture *color_map[SGCloudLayer::SG_MAX_CLOUD_COVERAGES][2] = { 0 };
  56 static GLuint normalization_cube_map;
  57
  58 static glActiveTextureProc glActiveTexturePtr = 0;
  59 static glClientActiveTextureProc glClientActiveTexturePtr = 0;
  60 static glBlendColorProc glBlendColorPtr = 0;
  61
  62 bool SGCloudLayer::enable_bump_mapping = false;
  63
  64 static void
  65 generateNormalizationCubeMap()
  66 {
  67     unsigned char data[ 32 * 32 * 3 ];
  68     const int size = 32;
  69     const float half_size = 16.0f,
  70                 offset = 0.5f;
  71     sgVec3 zero_normal;
  72     sgSetVec3( zero_normal, 0.5f, 0.5f, 0.5f );
  73     int i, j;
  74
  75     unsigned char *ptr = data;
  76     for ( j = 0; j < size; j++ ) {
  77         for ( i = 0; i < size; i++ ) {
  78             sgVec3 tmp;
  79             sgSetVec3( tmp, half_size,
  80                             -( j + offset - half_size ),
  81                             -( i + offset - half_size ) );
  82             sgNormalizeVec3( tmp );
  83             sgScaleVec3( tmp, 0.5f );
  84             sgAddVec3( tmp, zero_normal );
  85
  86             *ptr++ = (unsigned char)( tmp[ 0 ] * 255 );
  87             *ptr++ = (unsigned char)( tmp[ 1 ] * 255 );
  88             *ptr++ = (unsigned char)( tmp[ 2 ] * 255 );
  89         }
  90     }
  91     glTexImage2D( GL_TEXTURE_CUBE_MAP_POSITIVE_X_ARB,
  92                   0, GL_RGBA8, 32, 32, 0, GL_RGB, GL_UNSIGNED_BYTE, data );
  93
  94     ptr = data;
  95     for ( j = 0; j < size; j++ ) {
  96         for ( i = 0; i < size; i++ ) {
  97             sgVec3 tmp;
  98             sgSetVec3( tmp, -half_size,
  99                             -( j + offset - half_size ),
 100                             ( i + offset - half_size ) );
 101             sgNormalizeVec3( tmp );
 102             sgScaleVec3( tmp, 0.5f );
 103             sgAddVec3( tmp, zero_normal );
 104
 105             *ptr++ = (unsigned char)( tmp[ 0 ] * 255 );
 106             *ptr++ = (unsigned char)( tmp[ 1 ] * 255 );
 107             *ptr++ = (unsigned char)( tmp[ 2 ] * 255 );
 108         }
 109     }
 110     glTexImage2D( GL_TEXTURE_CUBE_MAP_NEGATIVE_X_ARB,
 111                   0, GL_RGBA8, 32, 32, 0, GL_RGB, GL_UNSIGNED_BYTE, data );
 112
 113     ptr = data;
 114     for ( j = 0; j < size; j++ ) {
 115         for ( i = 0; i < size; i++ ) {
 116             sgVec3 tmp;
 117             sgSetVec3( tmp, ( i + offset - half_size ),
 118                             half_size,
 119                             ( j + offset - half_size ) );
 120             sgNormalizeVec3( tmp );
 121             sgScaleVec3( tmp, 0.5f );
 122             sgAddVec3( tmp, zero_normal );
 123
 124             *ptr++ = (unsigned char)( tmp[ 0 ] * 255 );
 125             *ptr++ = (unsigned char)( tmp[ 1 ] * 255 );
 126             *ptr++ = (unsigned char)( tmp[ 2 ] * 255 );
 127         }
 128     }
 129     glTexImage2D( GL_TEXTURE_CUBE_MAP_POSITIVE_Y_ARB,
 130                   0, GL_RGBA8, 32, 32, 0, GL_RGB, GL_UNSIGNED_BYTE, data );
 131
 132     ptr = data;
 133     for ( j = 0; j < size; j++ ) {
 134         for ( i = 0; i < size; i++ ) {
 135             sgVec3 tmp;
 136             sgSetVec3( tmp, ( i + offset - half_size ),
 137                             -half_size,
 138                             -( j + offset - half_size ) );
 139             sgNormalizeVec3( tmp );
 140             sgScaleVec3( tmp, 0.5f );
 141             sgAddVec3( tmp, zero_normal );
 142
 143             *ptr++ = (unsigned char)( tmp[ 0 ] * 255 );
 144             *ptr++ = (unsigned char)( tmp[ 1 ] * 255 );
 145             *ptr++ = (unsigned char)( tmp[ 2 ] * 255 );
 146         }
 147     }
 148     glTexImage2D( GL_TEXTURE_CUBE_MAP_NEGATIVE_Y_ARB,
 149                   0, GL_RGBA8, 32, 32, 0, GL_RGB, GL_UNSIGNED_BYTE, data );
 150
 151     ptr = data;
 152     for ( j = 0; j < size; j++ ) {
 153         for ( i = 0; i < size; i++ ) {
 154             sgVec3 tmp;
 155             sgSetVec3( tmp, ( i + offset - half_size ),
 156                             -( j + offset - half_size ),
 157                             half_size );
 158             sgNormalizeVec3( tmp );
 159             sgScaleVec3( tmp, 0.5f );
 160             sgAddVec3( tmp, zero_normal );
 161
 162             *ptr++ = (unsigned char)( tmp[ 0 ] * 255 );
 163             *ptr++ = (unsigned char)( tmp[ 1 ] * 255 );
 164             *ptr++ = (unsigned char)( tmp[ 2 ] * 255 );
 165         }
 166     }
 167     glTexImage2D( GL_TEXTURE_CUBE_MAP_POSITIVE_Z_ARB,
 168                   0, GL_RGBA8, 32, 32, 0, GL_RGB, GL_UNSIGNED_BYTE, data );
 169
 170     ptr = data;
 171     for ( j = 0; j < size; j++ ) {
 172         for ( i = 0; i < size; i++ ) {
 173             sgVec3 tmp;
 174             sgSetVec3( tmp, -( i + offset - half_size ),
 175                             -( j + offset - half_size ),
 176                             -half_size );
 177             sgNormalizeVec3( tmp );
 178             sgScaleVec3( tmp, 0.5f );
 179             sgAddVec3( tmp, zero_normal );
 180
 181             *ptr++ = (unsigned char)( tmp[ 0 ] * 255 );
 182             *ptr++ = (unsigned char)( tmp[ 1 ] * 255 );
 183             *ptr++ = (unsigned char)( tmp[ 2 ] * 255 );
 184         }
 185     }
 186     glTexImage2D( GL_TEXTURE_CUBE_MAP_NEGATIVE_Z_ARB,
 187                   0, GL_RGBA8, 32, 32, 0, GL_RGB, GL_UNSIGNED_BYTE, data );
 188 }
 189
 190
 191 // Constructor
 192 SGCloudLayer::SGCloudLayer( const string &tex_path ) :
 193     layer_root(new ssgRoot),
 194     layer_transform(new ssgTransform),
 195     state_sel(0),
 196     texture_path(tex_path),
 197     layer_span(0.0),
 198     layer_asl(0.0),
 199     layer_thickness(0.0),
 200     layer_transition(0.0),
 201     layer_coverage(SG_CLOUD_CLEAR),
 202     scale(4000.0),
 203     speed(0.0),
 204     direction(0.0),
 205     last_lon(0.0),
 206     last_lat(0.0),
 207     vertices(0),
 208     indices(0)
 209 {
 210     cl[0] = cl[1] = cl[2] = cl[3] = NULL;
 211     vl[0] = vl[1] = vl[2] = vl[3] = NULL;
 212     tl[0] = tl[1] = tl[2] = tl[3] = NULL;
 213     layer[0] = layer[1] = layer[2] = layer[3] = NULL;
 214
 215     layer_root->addKid(layer_transform);
 216     rebuild();
 217 }
 218
 219 // Destructor
 220 SGCloudLayer::~SGCloudLayer()
 221 {
 222     delete vertices;
 223     delete indices;
 224     delete layer_root;          // deletes layer_transform and layer as well
 225 }
 226
 227 float
 228 SGCloudLayer::getSpan_m () const
 229 {
 230     return layer_span;
 231 }
 232
 233 void
 234 SGCloudLayer::setSpan_m (float span_m)
 235 {
 236     if (span_m != layer_span) {
 237         layer_span = span_m;
 238         rebuild();
 239     }
 240 }
 241
 242 float
 243 SGCloudLayer::getElevation_m () const
 244 {
 245     return layer_asl;
 246 }
 247
 248 void
 249 SGCloudLayer::setElevation_m (float elevation_m, bool set_span)
 250 {
 251     layer_asl = elevation_m;
 252
 253     if (set_span) {
 254         if (elevation_m > 4000)
 255             setSpan_m(  elevation_m * 10 );
 256         else
 257             setSpan_m( 40000 );
 258     }
 259 }
 260
 261 float
 262 SGCloudLayer::getThickness_m () const
 263 {
 264     return layer_thickness;
 265 }
 266
 267 void
 268 SGCloudLayer::setThickness_m (float thickness_m)
 269 {
 270     layer_thickness = thickness_m;
 271 }
 272
 273 float
 274 SGCloudLayer::getTransition_m () const
 275 {
 276     return layer_transition;
 277 }
 278
 279 void
 280 SGCloudLayer::setTransition_m (float transition_m)
 281 {
 282     layer_transition = transition_m;
 283 }
 284
 285 SGCloudLayer::Coverage
 286 SGCloudLayer::getCoverage () const
 287 {
 288     return layer_coverage;
 289 }
 290
 291 void
 292 SGCloudLayer::setCoverage (Coverage coverage)
 293 {
 294     if (coverage != layer_coverage) {
 295         layer_coverage = coverage;
 296         rebuild();
 297     }
 298 }
 299
 300
 301 // build the cloud object
 302 void
 303 SGCloudLayer::rebuild()
 304 {
 305     // Initialize states and sizes if necessary.
 306     if ( !state_initialized ) {
 307         state_initialized = true;
 308
 309         SG_LOG(SG_ASTRO, SG_INFO, "initializing cloud layers");
 310
 311         bump_mapping = SGIsOpenGLExtensionSupported("GL_ARB_multitexture") &&
 312                        SGIsOpenGLExtensionSupported("GL_ARB_texture_cube_map") &&
 313                        SGIsOpenGLExtensionSupported("GL_ARB_texture_env_combine") &&
 314                        SGIsOpenGLExtensionSupported("GL_ARB_texture_env_dot3") &&
 315                        SGIsOpenGLExtensionSupported("GL_ARB_imaging");
 316
 317         if ( bump_mapping ) {
 318             glGetIntegerv( GL_MAX_TEXTURE_UNITS_ARB, &nb_texture_unit );
 319             if ( nb_texture_unit < 2 ) {
 320                 bump_mapping = false;
 321             }
 322             nb_texture_unit = 2; // Force the number of units for now
 323         }
 324
 325         if ( bump_mapping ) {
 326
 327             // This bump mapping code was inspired by the tutorial available at
 328             // http://www.paulsprojects.net/tutorials/simplebump/simplebump.html
 329             // and a NVidia white paper
 330             //  http://developer.nvidia.com/object/bumpmappingwithregistercombiners.html
 331             // The normal map textures were generated by the normal map Gimp plugin :
 332             //  http://nifelheim.dyndns.org/~cocidius/normalmap/
 333             //
 334             SGPath cloud_path;
 335
 336             glActiveTexturePtr = (glActiveTextureProc)SGLookupFunction("glActiveTextureARB");
 337             glClientActiveTexturePtr = (glClientActiveTextureProc)SGLookupFunction("glClientActiveTextureARB");
 338             glBlendColorPtr = (glBlendColorProc)SGLookupFunction("glBlendColor");
 339
 340             cloud_path.set(texture_path.str());
 341             cloud_path.append("overcast.rgb");
 342             color_map[ SG_CLOUD_OVERCAST ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 343             color_map[ SG_CLOUD_OVERCAST ][ 0 ]->ref();
 344             cloud_path.set(texture_path.str());
 345             cloud_path.append("overcast_n.rgb");
 346             normal_map[ SG_CLOUD_OVERCAST ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 347             normal_map[ SG_CLOUD_OVERCAST ][ 0 ]->ref();
 348
 349             cloud_path.set(texture_path.str());
 350             cloud_path.append("overcast_top.rgb");
 351             color_map[ SG_CLOUD_OVERCAST ][ 1 ] = new ssgTexture( cloud_path.str().c_str() );
 352             color_map[ SG_CLOUD_OVERCAST ][ 1 ]->ref();
 353             cloud_path.set(texture_path.str());
 354             cloud_path.append("overcast_top_n.rgb");
 355             normal_map[ SG_CLOUD_OVERCAST ][ 1 ] = new ssgTexture( cloud_path.str().c_str() );
 356             normal_map[ SG_CLOUD_OVERCAST ][ 1 ]->ref();
 357
 358             cloud_path.set(texture_path.str());
 359             cloud_path.append("broken.rgba");
 360             color_map[ SG_CLOUD_BROKEN ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 361             color_map[ SG_CLOUD_BROKEN ][ 0 ]->ref();
 362             cloud_path.set(texture_path.str());
 363             cloud_path.append("broken_n.rgb");
 364             normal_map[ SG_CLOUD_BROKEN ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 365             normal_map[ SG_CLOUD_BROKEN ][ 0 ]->ref();
 366
 367             cloud_path.set(texture_path.str());
 368             cloud_path.append("scattered.rgba");
 369             color_map[ SG_CLOUD_SCATTERED ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 370             color_map[ SG_CLOUD_SCATTERED ][ 0 ]->ref();
 371             cloud_path.set(texture_path.str());
 372             cloud_path.append("scattered_n.rgb");
 373             normal_map[ SG_CLOUD_SCATTERED ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 374             normal_map[ SG_CLOUD_SCATTERED ][ 0 ]->ref();
 375
 376             cloud_path.set(texture_path.str());
 377             cloud_path.append("few.rgba");
 378             color_map[ SG_CLOUD_FEW ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 379             color_map[ SG_CLOUD_FEW ][ 0 ]->ref();
 380             cloud_path.set(texture_path.str());
 381             cloud_path.append("few_n.rgb");
 382             normal_map[ SG_CLOUD_FEW ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 383             normal_map[ SG_CLOUD_FEW ][ 0 ]->ref();
 384
 385             cloud_path.set(texture_path.str());
 386             cloud_path.append("cirrus.rgba");
 387             color_map[ SG_CLOUD_CIRRUS ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 388             color_map[ SG_CLOUD_CIRRUS ][ 0 ]->ref();
 389             cloud_path.set(texture_path.str());
 390             cloud_path.append("cirrus_n.rgb");
 391             normal_map[ SG_CLOUD_CIRRUS ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 392             normal_map[ SG_CLOUD_CIRRUS ][ 0 ]->ref();
 393
 394             glGenTextures( 1, &normalization_cube_map );
 395             glBindTexture( GL_TEXTURE_CUBE_MAP_ARB, normalization_cube_map );
 396             generateNormalizationCubeMap();
 397             glTexParameteri( GL_TEXTURE_CUBE_MAP_ARB, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
 398             glTexParameteri( GL_TEXTURE_CUBE_MAP_ARB, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
 399             glTexParameteri( GL_TEXTURE_CUBE_MAP_ARB, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );
 400             glTexParameteri( GL_TEXTURE_CUBE_MAP_ARB, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE );
 401             glTexParameteri( GL_TEXTURE_CUBE_MAP_ARB, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE );
 402         } /* else */ {
 403             SGPath cloud_path;
 404             ssgStateSelector *state_sel;
 405             ssgSimpleState *state;
 406
 407             state_sel = new ssgStateSelector( 2 );
 408             state_sel->ref();
 409             cloud_path.set(texture_path.str());
 410             cloud_path.append("overcast.rgb");
 411             state_sel->setStep( 0, sgCloudMakeState(cloud_path.str()) );
 412             cloud_path.set(texture_path.str());
 413             cloud_path.append("overcast_top.rgb");
 414             state_sel->setStep( 1, sgCloudMakeState(cloud_path.str()) );
 415             layer_states[SG_CLOUD_OVERCAST] = state_sel;
 416
 417             state_sel = new ssgStateSelector( 2 );
 418             state_sel->ref();
 419             cloud_path.set(texture_path.str());
 420             cloud_path.append("broken.rgba");
 421             state = sgCloudMakeState(cloud_path.str());
 422             state_sel->setStep( 0, state );
 423             state_sel->setStep( 1, state );
 424             layer_states[SG_CLOUD_BROKEN] = state_sel;
 425
 426             state_sel = new ssgStateSelector( 2 );
 427             state_sel->ref();
 428             cloud_path.set(texture_path.str());
 429             cloud_path.append("scattered.rgba");
 430             state = sgCloudMakeState(cloud_path.str());
 431             state_sel->setStep( 0, state );
 432             state_sel->setStep( 1, state );
 433             layer_states[SG_CLOUD_SCATTERED] = state_sel;
 434
 435             state_sel = new ssgStateSelector( 2 );
 436             state_sel->ref();
 437             cloud_path.set(texture_path.str());
 438             cloud_path.append("few.rgba");
 439             state = sgCloudMakeState(cloud_path.str());
 440             state_sel->setStep( 0, state );
 441             state_sel->setStep( 1, state );
 442             layer_states[SG_CLOUD_FEW] = state_sel;
 443
 444             state_sel = new ssgStateSelector( 2 );
 445             state_sel->ref();
 446             cloud_path.set(texture_path.str());
 447             cloud_path.append("cirrus.rgba");
 448             state = sgCloudMakeState(cloud_path.str());
 449             state_sel->setStep( 0, state );
 450             state_sel->setStep( 1, state );
 451             layer_states[SG_CLOUD_CIRRUS] = state_sel;
 452
 453             layer_states[SG_CLOUD_CLEAR] = 0;
 454         }
 455     }
 456
 457     if ( bump_mapping ) {
 458
 459         if ( !vertices ) {
 460             vertices = new CloudVertex[ 25 ];
 461             indices = new unsigned int[ 40 ];
 462         }
 463
 464         sgVec2 base;
 465         sgSetVec2( base, sg_random(), sg_random() );
 466
 467         const float layer_scale = layer_span / scale;
 468         const float layer_to_core = (SG_EARTH_RAD * 1000 + layer_asl);
 469         const float half_angle = 0.5 * layer_span / layer_to_core;
 470
 471         int i;
 472         for ( i = -2; i <= 2; i++ ) {
 473             for ( int j = -2; j <= 2; j++ ) {
 474                 CloudVertex &v1 = vertices[ (i+2)*5 + (j+2) ];
 475                 sgSetVec3( v1.position,
 476                            0.5 * i * layer_span,
 477                            0.5 * j * layer_span,
 478                            -layer_to_core * ( 1 - cos( i * half_angle ) * cos( j * half_angle ) ) );
 479                 sgSetVec2( v1.texCoord,
 480                            base[0] + layer_scale * i * 0.25,
 481                            base[1] + layer_scale * j * 0.25 );
 482                 sgSetVec3( v1.sTangent,
 483                            cos( i * half_angle ),
 484                            0.f,
 485                            -sin( i * half_angle ) );
 486                 sgSetVec3( v1.tTangent,
 487                            0.f,
 488                            cos( j * half_angle ),
 489                            -sin( j * half_angle ) );
 490                 sgVectorProductVec3( v1.normal, v1.tTangent, v1.sTangent );
 491                 sgSetVec4( v1.color, 1.0f, 1.0f, 1.0f, (i == 0) ? 0.0f : 0.15f );
 492             }
 493         }
 494         /*
 495          * 0 1 5 6 10 11 15 16 20 21
 496          * 1 2 6 7 11 12 16 17 21 22
 497          * 2 3 7 8 12 13 17 18 22 23
 498          * 3 4 8 9 13 14 18 19 23 24
 499          */
 500         for ( i = 0; i < 4; i++ ) {
 501             for ( int j = 0; j < 5; j++ ) {
 502                 indices[ i*10 + (j*2) ]     =     i + 5 * j;
 503                 indices[ i*10 + (j*2) + 1 ] = 1 + i + 5 * j;
 504             }
 505         }
 506
 507     } /* else */ {
 508
 509         scale = 4000.0;
 510         last_lon = last_lat = -999.0f;
 511
 512         sgVec2 base;
 513         sgSetVec2( base, sg_random(), sg_random() );
 514
 515         // build the cloud layer
 516         sgVec4 color;
 517         sgVec3 vertex;
 518         sgVec2 tc;
 519
 520         const float layer_scale = layer_span / scale;
 521         const float mpi = SG_PI/4;
 522
 523         // caclculate the difference between a flat-earth model and
 524         // a round earth model given the span and altutude ASL of
 525         // the cloud layer. This is the difference in altitude between
 526         // the top of the inverted bowl and the edge of the bowl.
 527         // const float alt_diff = layer_asl * 0.8;
 528         const float layer_to_core = (SG_EARTH_RAD * 1000 + layer_asl);
 529         const float layer_angle = 0.5*layer_span / layer_to_core; // The angle is half the span
 530         const float border_to_core = layer_to_core * cos(layer_angle);
 531         const float alt_diff = layer_to_core - border_to_core;
 532
 533         for (int i = 0; i < 4; i++)
 534         {
 535             if ( layer[i] != NULL ) {
 536                 layer_transform->removeKid(layer[i]); // automatic delete
 537             }
 538
 539             vl[i] = new ssgVertexArray( 10 );
 540             cl[i] = new ssgColourArray( 10 );
 541             tl[i] = new ssgTexCoordArray( 10 );
 542
 543
 544             sgSetVec3( vertex, layer_span*(i-2)/2, -layer_span,
 545                             alt_diff * (sin(i*mpi) - 2) );
 546
 547             sgSetVec2( tc, base[0] + layer_scale * i/4, base[1] );
 548
 549             sgSetVec4( color, 1.0f, 1.0f, 1.0f, (i == 0) ? 0.0f : 0.15f );
 550
 551             cl[i]->add( color );
 552             vl[i]->add( vertex );
 553             tl[i]->add( tc );
 554
 555             for (int j = 0; j < 4; j++)
 556             {
 557                 sgSetVec3( vertex, layer_span*(i-1)/2, layer_span*(j-2)/2,
 558                                 alt_diff * (sin((i+1)*mpi) + sin(j*mpi) - 2) );
 559
 560                 sgSetVec2( tc, base[0] + layer_scale * (i+1)/4,
 561                             base[1] + layer_scale * j/4 );
 562
 563                 sgSetVec4( color, 1.0f, 1.0f, 1.0f,
 564                                 ( (j == 0) || (i == 3)) ?
 565                                 ( (j == 0) && (i == 3)) ? 0.0f : 0.15f : 1.0f );
 566
 567                 cl[i]->add( color );
 568                 vl[i]->add( vertex );
 569                 tl[i]->add( tc );
 570
 571
 572                 sgSetVec3( vertex, layer_span*(i-2)/2, layer_span*(j-1)/2,
 573                                 alt_diff * (sin(i*mpi) + sin((j+1)*mpi) - 2) );
 574
 575                 sgSetVec2( tc, base[0] + layer_scale * i/4,
 576                             base[1] + layer_scale * (j+1)/4 );
 577
 578                 sgSetVec4( color, 1.0f, 1.0f, 1.0f,
 579                                 ((j == 3) || (i == 0)) ?
 580                                 ((j == 3) && (i == 0)) ? 0.0f : 0.15f : 1.0f );
 581                 cl[i]->add( color );
 582                 vl[i]->add( vertex );
 583                 tl[i]->add( tc );
 584             }
 585
 586             sgSetVec3( vertex, layer_span*(i-1)/2, layer_span,
 587                             alt_diff * (sin((i+1)*mpi) - 2) );
 588
 589             sgSetVec2( tc, base[0] + layer_scale * (i+1)/4,
 590                         base[1] + layer_scale );
 591
 592             sgSetVec4( color, 1.0f, 1.0f, 1.0f, (i == 3) ? 0.0f : 0.15f );
 593
 594             cl[i]->add( color );
 595             vl[i]->add( vertex );
 596             tl[i]->add( tc );
 597
 598             layer[i] = new ssgVtxTable(GL_TRIANGLE_STRIP, vl[i], NULL, tl[i], cl[i]);
 599             layer_transform->addKid( layer[i] );
 600
 601             if ( layer_states[layer_coverage] != NULL ) {
 602                 layer[i]->setState( layer_states[layer_coverage] );
 603             }
 604             state_sel = layer_states[layer_coverage];
 605         }
 606
 607         // force a repaint of the sky colors with arbitrary defaults
 608         repaint( color );
 609     }
 610 }
 611
 612
 613 // repaint the cloud layer colors
 614 bool SGCloudLayer::repaint( sgVec3 fog_color ) {
 615
 616     if ( bump_mapping && enable_bump_mapping ) {
 617
 618         for ( int i = 0; i < 25; i++ ) {
 619             sgCopyVec3( vertices[ i ].color, fog_color );
 620         }
 621
 622     } else {
 623         float *color;
 624
 625         for ( int i = 0; i < 4; i++ ) {
 626             for ( int j = 0; j < 10; ++j ) {
 627                 color = cl[i]->get( j );
 628                 sgCopyVec3( color, fog_color );
 629             }
 630         }
 631     }
 632
 633     return true;
 634 }
 635
 636
 637 // reposition the cloud layer at the specified origin and orientation
 638 // lon specifies a rotation about the Z axis
 639 // lat specifies a rotation about the new Y axis
 640 // spin specifies a rotation about the new Z axis (and orients the
 641 // sunrise/set effects
 642 bool SGCloudLayer::reposition( sgVec3 p, sgVec3 up, double lon, double lat,
 643                                double alt, double dt )
 644 {
 645     sgMat4 T1, LON, LAT;
 646     sgVec3 axis;
 647
 648     // combine p and asl (meters) to get translation offset
 649     sgVec3 asl_offset;
 650     sgCopyVec3( asl_offset, up );
 651     sgNormalizeVec3( asl_offset );
 652     if ( alt <= layer_asl ) {
 653         sgScaleVec3( asl_offset, layer_asl );
 654     } else {
 655         sgScaleVec3( asl_offset, layer_asl + layer_thickness );
 656     }
 657     // cout << "asl_offset = " << asl_offset[0] << "," << asl_offset[1]
 658     //      << "," << asl_offset[2] << endl;
 659     sgAddVec3( asl_offset, p );
 660     // cout << "  asl_offset = " << asl_offset[0] << "," << asl_offset[1]
 661     //      << "," << asl_offset[2] << endl;
 662
 663     // Translate to zero elevation
 664     // Point3D zero_elev = current_view.get_cur_zero_elev();
 665     sgMakeTransMat4( T1, asl_offset );
 666
 667     // printf("  Translated to %.2f %.2f %.2f\n",
 668     //        zero_elev.x, zero_elev.y, zero_elev.z );
 669
 670     // Rotate to proper orientation
 671     // printf("  lon = %.2f  lat = %.2f\n",
 672     //        lon * SGD_RADIANS_TO_DEGREES,
 673     //        lat * SGD_RADIANS_TO_DEGREES);
 674     sgSetVec3( axis, 0.0, 0.0, 1.0 );
 675     sgMakeRotMat4( LON, lon * SGD_RADIANS_TO_DEGREES, axis );
 676
 677     sgSetVec3( axis, 0.0, 1.0, 0.0 );
 678     sgMakeRotMat4( LAT, 90.0 - lat * SGD_RADIANS_TO_DEGREES, axis );
 679
 680     sgMat4 TRANSFORM;
 681
 682     sgCopyMat4( TRANSFORM, T1 );
 683     sgPreMultMat4( TRANSFORM, LON );
 684     sgPreMultMat4( TRANSFORM, LAT );
 685
 686     sgCoord layerpos;
 687     sgSetCoord( &layerpos, TRANSFORM );
 688
 689     layer_transform->setTransform( &layerpos );
 690
 691     // now calculate update texture coordinates
 692     if ( last_lon < -900 ) {
 693         last_lon = lon;
 694         last_lat = lat;
 695     }
 696
 697     double sp_dist = speed*dt;
 698
 699     if ( lon != last_lon || lat != last_lat || sp_dist != 0 ) {
 700         Point3D start( last_lon, last_lat, 0.0 );
 701         Point3D dest( lon, lat, 0.0 );
 702         double course = 0.0, dist = 0.0;
 703
 704         calc_gc_course_dist( dest, start, &course, &dist );
 705         // cout << "course = " << course << ", dist = " << dist << endl;
 706
 707         // if start and dest are too close together,
 708         // calc_gc_course_dist() can return a course of "nan".  If
 709         // this happens, lets just use the last known good course.
 710         // This is a hack, and it would probably be better to make
 711         // calc_gc_course_dist() more robust.
 712         if ( isnan(course) ) {
 713             course = last_course;
 714         } else {
 715             last_course = course;
 716         }
 717
 718         // calculate cloud movement due to external forces
 719         double ax = 0.0, ay = 0.0, bx = 0.0, by = 0.0;
 720
 721         if (dist > 0.0) {
 722             ax = cos(course) * dist;
 723             ay = sin(course) * dist;
 724         }
 725
 726         if (sp_dist > 0) {
 727             bx = cos(-direction * SGD_DEGREES_TO_RADIANS) * sp_dist;
 728             by = sin(-direction * SGD_DEGREES_TO_RADIANS) * sp_dist;
 729         }
 730
 731
 732         double xoff = (ax + bx) / (2 * scale);
 733         double yoff = (ay + by) / (2 * scale);
 734
 735         const float layer_scale = layer_span / scale;
 736
 737         // cout << "xoff = " << xoff << ", yoff = " << yoff << endl;
 738
 739         float *base;
 740         if ( bump_mapping && enable_bump_mapping ) {
 741             base = vertices[12].texCoord;
 742         } else {
 743             base = tl[0]->get( 0 );
 744         }
 745         base[0] += xoff;
 746
 747         // the while loops can lead to *long* pauses if base[0] comes
 748         // with a bogus value.
 749         // while ( base[0] > 1.0 ) { base[0] -= 1.0; }
 750         // while ( base[0] < 0.0 ) { base[0] += 1.0; }
 751         if ( base[0] > -10.0 && base[0] < 10.0 ) {
 752             base[0] -= (int)base[0];
 753         } else {
 754             SG_LOG(SG_ASTRO, SG_DEBUG,
 755                 "Error: base = " << base[0] << "," << base[1] <<
 756                 " course = " << course << " dist = " << dist );
 757             base[0] = 0.0;
 758         }
 759
 760         base[1] += yoff;
 761         // the while loops can lead to *long* pauses if base[0] comes
 762         // with a bogus value.
 763         // while ( base[1] > 1.0 ) { base[1] -= 1.0; }
 764         // while ( base[1] < 0.0 ) { base[1] += 1.0; }
 765         if ( base[1] > -10.0 && base[1] < 10.0 ) {
 766             base[1] -= (int)base[1];
 767         } else {
 768             SG_LOG(SG_ASTRO, SG_ALERT,
 769                     "Error: base = " << base[0] << "," << base[1] <<
 770                     " course = " << course << " dist = " << dist );
 771             base[1] = 0.0;
 772         }
 773
 774         if ( bump_mapping && enable_bump_mapping ) {
 775
 776             for ( int i = -2; i <= 2; i++ ) {
 777                 for ( int j = -2; j <= 2; j++ ) {
 778                     if ( i == 0 && j == 0 )
 779                         continue; // Already done on base
 780                     CloudVertex &v1 = vertices[ (i+2)*5 + (j+2) ];
 781                     sgSetVec2( v1.texCoord,
 782                             base[0] + layer_scale * i * 0.25,
 783                             base[1] + layer_scale * j * 0.25 );
 784                 }
 785             }
 786
 787         } else {
 788                 // cout << "base = " << base[0] << "," << base[1] << endl;
 789
 790             float *tc;
 791             for (int i = 0; i < 4; i++) {
 792                 tc = tl[i]->get( 0 );
 793                 sgSetVec2( tc, base[0] + layer_scale * i/4, base[1] );
 794
 795                 for (int j = 0; j < 4; j++)
 796                 {
 797                     tc = tl[i]->get( j*2+1 );
 798                     sgSetVec2( tc, base[0] + layer_scale * (i+1)/4,
 799                                 base[1] + layer_scale * j/4 );
 800
 801                     tc = tl[i]->get( (j+1)*2 );
 802                     sgSetVec2( tc, base[0] + layer_scale * i/4,
 803                                 base[1] + layer_scale * (j+1)/4 );
 804                 }
 805
 806                 tc = tl[i]->get( 9 );
 807                 sgSetVec2( tc, base[0] + layer_scale * (i+1)/4,
 808                             base[1] + layer_scale );
 809             }
 810         }
 811
 812         last_lon = lon;
 813         last_lat = lat;
 814     }
 815
 816     return true;
 817 }
 818
 819
 820 void SGCloudLayer::draw( bool top ) {
 821     if ( layer_coverage != SG_CLOUD_CLEAR ) {
 822
 823         if ( bump_mapping && enable_bump_mapping ) {
 824
 825             sgMat4 modelview,
 826                    tmp,
 827                    transform;
 828             ssgGetModelviewMatrix( modelview );
 829             layer_transform->getTransform( transform );
 830
 831             sgInvertMat4( tmp, transform );
 832
 833             sgPostMultMat4( transform, modelview );
 834             ssgLoadModelviewMatrix( transform );
 835
 836             sgVec3 lightVec;
 837             ssgGetLight( 0 )->getPosition( lightVec );
 838             sgNegateVec3( lightVec );
 839             sgXformVec3( lightVec, tmp );
 840
 841             for ( int i = 0; i < 25; i++ ) {
 842                 CloudVertex &v = vertices[ i ];
 843                 sgSetVec3( v.tangentSpLight,
 844                            sgScalarProductVec3( v.sTangent, lightVec ),
 845                            sgScalarProductVec3( v.tTangent, lightVec ),
 846                            sgScalarProductVec3( v.normal, lightVec ) );
 847             }
 848
 849             ssgTexture *decal = color_map[ layer_coverage ][ top ? 1 : 0 ];
 850             if ( top && decal == 0 ) {
 851                 decal = color_map[ layer_coverage ][ 0 ];
 852             }
 853             ssgTexture *normal = normal_map[ layer_coverage ][ top ? 1 : 0 ];
 854             if ( top && normal == 0 ) {
 855                 normal = normal_map[ layer_coverage ][ 0 ];
 856             }
 857
 858             glDisable( GL_LIGHTING );
 859             glDisable( GL_CULL_FACE );
 860             if ( layer_coverage == SG_CLOUD_FEW ) {
 861                 glEnable( GL_ALPHA_TEST );
 862                 glAlphaFunc ( GL_GREATER, 0.01 );
 863             }
 864             glEnable( GL_BLEND );
 865             glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
 866
 867             glPolygonMode( GL_FILL, GL_FRONT_AND_BACK );
 868             glShadeModel( GL_SMOOTH );
 869             glEnable( GL_COLOR_MATERIAL );
 870             sgVec4 color;
 871             sgSetVec4( color, 0.05, 0.05, 0.05, 0.0 );
 872             glMaterialfv( GL_FRONT_AND_BACK, GL_EMISSION, color );
 873             sgSetVec4( color, 0.8, 0.8, 0.8, 0.0 );
 874             glMaterialfv( GL_FRONT_AND_BACK, GL_AMBIENT, color );
 875             sgSetVec4( color, 0.5, 0.5, 0.5, 0.0 );
 876             glMaterialfv( GL_FRONT_AND_BACK, GL_DIFFUSE, color );
 877             sgSetVec4( color, 1.0, 1.0, 1.0, 1.0 );
 878             glMaterialfv( GL_FRONT_AND_BACK, GL_SPECULAR, color );
 879
 880             glActiveTexturePtr( GL_TEXTURE0_ARB );
 881             glBindTexture( GL_TEXTURE_2D, normal->getHandle() );
 882             glEnable( GL_TEXTURE_2D );
 883
 884             //Bind normalisation cube map to texture unit 1
 885             glActiveTexturePtr( GL_TEXTURE1_ARB );
 886             glBindTexture( GL_TEXTURE_CUBE_MAP_ARB, normalization_cube_map );
 887             glEnable( GL_TEXTURE_CUBE_MAP_ARB );
 888             glActiveTexturePtr( GL_TEXTURE0_ARB );
 889
 890             //Set vertex arrays for cloud
 891             glVertexPointer( 3, GL_FLOAT, sizeof(CloudVertex), &vertices[0].position );
 892             glEnableClientState( GL_VERTEX_ARRAY );
 893
 894             if ( nb_texture_unit >= 3 ) {
 895                 glColorPointer( 4, GL_FLOAT, sizeof(CloudVertex), &vertices[0].color );
 896                 glEnableClientState( GL_COLOR_ARRAY );
 897             }
 898
 899             //Send texture coords for normal map to unit 0
 900             glTexCoordPointer( 2, GL_FLOAT, sizeof(CloudVertex), &vertices[0].texCoord );
 901             glEnableClientState( GL_TEXTURE_COORD_ARRAY );
 902
 903             //Send tangent space light vectors for normalisation to unit 1
 904             glClientActiveTexturePtr( GL_TEXTURE1_ARB );
 905             glTexCoordPointer( 3, GL_FLOAT, sizeof(CloudVertex), &vertices[0].tangentSpLight );
 906             glEnableClientState( GL_TEXTURE_COORD_ARRAY );
 907
 908             //Set up texture environment to do (tex0 dot tex1)*color
 909             glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_ARB );
 910             glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_RGB_ARB, GL_TEXTURE );
 911             glTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_RGB_ARB, GL_REPLACE );
 912             glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_ALPHA_ARB, GL_TEXTURE );
 913             glTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_ALPHA_ARB, GL_REPLACE );
 914
 915             glActiveTexturePtr( GL_TEXTURE1_ARB );
 916
 917             glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_ARB );
 918             glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_RGB_ARB, GL_TEXTURE );
 919             glTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_RGB_ARB, GL_DOT3_RGB_ARB );
 920             glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE1_RGB_ARB, GL_PREVIOUS_ARB );
 921             glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_ALPHA_ARB, GL_PREVIOUS_ARB );
 922             glTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_ALPHA_ARB, GL_REPLACE );
 923
 924             if ( nb_texture_unit >= 3 ) {
 925                 glActiveTexturePtr( GL_TEXTURE2_ARB );
 926                 glBindTexture( GL_TEXTURE_2D, decal->getHandle() );
 927
 928                 glClientActiveTexturePtr( GL_TEXTURE2_ARB );
 929                 glTexCoordPointer( 2, GL_FLOAT, sizeof(CloudVertex), &vertices[0].texCoord );
 930                 glEnableClientState( GL_TEXTURE_COORD_ARRAY );
 931
 932                 sgVec4 factors;
 933                 if ( top || layer_coverage != SG_CLOUD_OVERCAST ) {
 934                     sgSetVec4( factors, 0.5f, 0.5f, 0.3f, 1.0f );
 935                 } else {
 936                     sgSetVec4( factors, 0.1f, 0.1f, 0.0f, 1.0f );
 937                 }
 938                 glTexEnvfv( GL_TEXTURE_ENV, GL_TEXTURE_ENV_COLOR, factors );
 939
 940                 glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_ARB );
 941                 glTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_RGB_ARB, GL_INTERPOLATE_ARB );
 942                 glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_RGB_ARB, GL_TEXTURE );
 943                 glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE1_RGB_ARB, GL_PREVIOUS_ARB );
 944                 glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE2_RGB_ARB, GL_CONSTANT_ARB );
 945
 946                 glClientActiveTexturePtr( GL_TEXTURE0_ARB );
 947                 glActiveTexturePtr( GL_TEXTURE0_ARB );
 948
 949                 //Draw cloud layer
 950                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[0] );
 951                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[10] );
 952                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[20] );
 953                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[30] );
 954
 955                 glDisable( GL_TEXTURE_2D );
 956                 glActiveTexturePtr( GL_TEXTURE1_ARB );
 957                 glDisable( GL_TEXTURE_CUBE_MAP_ARB );
 958                 glActiveTexturePtr( GL_TEXTURE2_ARB );
 959                 glDisable( GL_TEXTURE_2D );
 960                 glActiveTexturePtr( GL_TEXTURE0_ARB );
 961
 962                 glDisableClientState( GL_TEXTURE_COORD_ARRAY );
 963                 glClientActiveTexturePtr( GL_TEXTURE1_ARB );
 964                 glDisableClientState( GL_TEXTURE_COORD_ARRAY );
 965                 glClientActiveTexturePtr( GL_TEXTURE2_ARB );
 966                 glDisableClientState( GL_TEXTURE_COORD_ARRAY );
 967                 glClientActiveTexturePtr( GL_TEXTURE0_ARB );
 968
 969                 glDisableClientState( GL_COLOR_ARRAY );
 970                 glEnable( GL_LIGHTING );
 971
 972                 glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
 973
 974             } else {
 975                 glClientActiveTexturePtr( GL_TEXTURE0_ARB );
 976                 glActiveTexturePtr( GL_TEXTURE0_ARB );
 977
 978                 //Draw cloud layer
 979                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[0] );
 980                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[10] );
 981                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[20] );
 982                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[30] );
 983
 984                 //Disable textures
 985                 glDisable( GL_TEXTURE_2D );
 986
 987                 glActiveTexturePtr( GL_TEXTURE1_ARB );
 988                 glDisable( GL_TEXTURE_CUBE_MAP_ARB );
 989                 glActiveTexturePtr( GL_TEXTURE0_ARB );
 990
 991                 //disable vertex arrays
 992                 glDisableClientState( GL_VERTEX_ARRAY );
 993
 994                 glDisableClientState( GL_TEXTURE_COORD_ARRAY );
 995                 glClientActiveTexturePtr( GL_TEXTURE1_ARB );
 996                 glDisableClientState( GL_TEXTURE_COORD_ARRAY );
 997                 glClientActiveTexturePtr( GL_TEXTURE0_ARB );
 998
 999                 //Return to standard modulate texenv
1000                 glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
1001
1002                 glDepthFunc(GL_LEQUAL);
1003
1004                 glEnable( GL_LIGHTING );
1005                 sgVec4 color;
1006                 ssgGetLight( 0 )->getColour( GL_DIFFUSE, color );
1007                 float average = ( color[0] + color[1] + color[2] ) / 3.0f;
1008                 sgVec4 averageColor;
1009                 sgSetVec4( averageColor, average, average, average, 1.0f );
1010                 ssgGetLight( 0 )->setColour( GL_DIFFUSE, averageColor );
1011
1012                 glBlendColorPtr( average, average, average, 1.0f );
1013                 glBlendFunc( GL_ONE_MINUS_CONSTANT_COLOR, GL_CONSTANT_COLOR );
1014
1015                 //Perform a second pass to color the torus
1016                 //Bind decal texture
1017                 glBindTexture( GL_TEXTURE_2D, decal->getHandle() );
1018                 glEnable(GL_TEXTURE_2D);
1019
1020                 //Set vertex arrays for torus
1021                 glVertexPointer( 3, GL_FLOAT, sizeof(CloudVertex), &vertices[0].position );
1022                 glEnableClientState( GL_VERTEX_ARRAY );
1023
1024                 //glColorPointer( 4, GL_FLOAT, sizeof(CloudVertex), &vertices[0].color );
1025                 //glEnableClientState( GL_COLOR_ARRAY );
1026
1027                 glNormalPointer( GL_FLOAT, sizeof(CloudVertex), &vertices[0].normal );
1028                 glEnableClientState( GL_NORMAL_ARRAY );
1029
1030                 glTexCoordPointer( 2, GL_FLOAT, sizeof(CloudVertex), &vertices[0].texCoord );
1031                 glEnableClientState( GL_TEXTURE_COORD_ARRAY );
1032
1033                 //Draw cloud layer
1034                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[0] );
1035                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[10] );
1036                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[20] );
1037                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[30] );
1038
1039                 ssgGetLight( 0 )->setColour( GL_DIFFUSE, color );
1040
1041                 glDisableClientState( GL_TEXTURE_COORD_ARRAY );
1042             }
1043             //Disable texture
1044             glDisable( GL_TEXTURE_2D );
1045
1046             glDisableClientState( GL_VERTEX_ARRAY );
1047             glDisableClientState( GL_NORMAL_ARRAY );
1048
1049             glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
1050             glEnable( GL_CULL_FACE );
1051             glDepthFunc(GL_LESS);
1052
1053             ssgLoadModelviewMatrix( modelview );
1054
1055         } else {
1056             state_sel->selectStep( top ? 1 : 0 );
1057             ssgCullAndDraw( layer_root );
1058         }
1059     }
1060 }
1061
1062
1063 // make an ssgSimpleState for a cloud layer given the named texture
1064 ssgSimpleState *sgCloudMakeState( const string &path ) {
1065     ssgSimpleState *state = new ssgSimpleState();
1066
1067     SG_LOG(SG_ASTRO, SG_INFO, " texture = ");
1068
1069     state->setTexture( (char *)path.c_str() );
1070     state->setShadeModel( GL_SMOOTH );
1071     state->disable( GL_LIGHTING );
1072     state->disable( GL_CULL_FACE );
1073     state->enable( GL_TEXTURE_2D );
1074     state->enable( GL_COLOR_MATERIAL );
1075     state->setColourMaterial( GL_AMBIENT_AND_DIFFUSE );
1076     state->setMaterial( GL_EMISSION, 0.05, 0.05, 0.05, 0.0 );
1077     state->setMaterial( GL_AMBIENT, 0.2, 0.2, 0.2, 0.0 );
1078     state->setMaterial( GL_DIFFUSE, 0.5, 0.5, 0.5, 0.0 );
1079     state->setMaterial( GL_SPECULAR, 0.0, 0.0, 0.0, 0.0 );
1080     state->enable( GL_BLEND );
1081     state->enable( GL_ALPHA_TEST );
1082     state->setAlphaClamp( 0.01 );
1083
1084     return state;
1085 }