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 #if defined(__MINGW32__)
  47 #define isnan(x) _isnan(x)
  48 #endif
  49
  50
  51 static ssgStateSelector *layer_states[SGCloudLayer::SG_MAX_CLOUD_COVERAGES];
  52 static bool state_initialized = false;
  53 static bool bump_mapping = false;
  54 static int nb_texture_unit = 0;
  55 static ssgTexture *normal_map[SGCloudLayer::SG_MAX_CLOUD_COVERAGES][2] = { 0 };
  56 static ssgTexture *color_map[SGCloudLayer::SG_MAX_CLOUD_COVERAGES][2] = { 0 };
  57 static GLuint normalization_cube_map;
  58
  59 static glActiveTextureProc glActiveTexturePtr = 0;
  60 static glClientActiveTextureProc glClientActiveTexturePtr = 0;
  61 static glBlendColorProc glBlendColorPtr = 0;
  62
  63 bool SGCloudLayer::enable_bump_mapping = false;
  64
  65 static void
  66 generateNormalizationCubeMap()
  67 {
  68     unsigned char data[ 32 * 32 * 3 ];
  69     const int size = 32;
  70     const float half_size = 16.0f,
  71                 offset = 0.5f;
  72     sgVec3 zero_normal;
  73     sgSetVec3( zero_normal, 0.5f, 0.5f, 0.5f );
  74     int i, j;
  75
  76     unsigned char *ptr = data;
  77     for ( j = 0; j < size; j++ ) {
  78         for ( i = 0; i < size; i++ ) {
  79             sgVec3 tmp;
  80             sgSetVec3( tmp, half_size,
  81                             -( j + offset - half_size ),
  82                             -( i + offset - half_size ) );
  83             sgNormalizeVec3( tmp );
  84             sgScaleVec3( tmp, 0.5f );
  85             sgAddVec3( tmp, zero_normal );
  86
  87             *ptr++ = (unsigned char)( tmp[ 0 ] * 255 );
  88             *ptr++ = (unsigned char)( tmp[ 1 ] * 255 );
  89             *ptr++ = (unsigned char)( tmp[ 2 ] * 255 );
  90         }
  91     }
  92     glTexImage2D( GL_TEXTURE_CUBE_MAP_POSITIVE_X_ARB,
  93                   0, GL_RGBA8, 32, 32, 0, GL_RGB, GL_UNSIGNED_BYTE, data );
  94
  95     ptr = data;
  96     for ( j = 0; j < size; j++ ) {
  97         for ( i = 0; i < size; i++ ) {
  98             sgVec3 tmp;
  99             sgSetVec3( tmp, -half_size,
 100                             -( j + offset - half_size ),
 101                             ( i + offset - half_size ) );
 102             sgNormalizeVec3( tmp );
 103             sgScaleVec3( tmp, 0.5f );
 104             sgAddVec3( tmp, zero_normal );
 105
 106             *ptr++ = (unsigned char)( tmp[ 0 ] * 255 );
 107             *ptr++ = (unsigned char)( tmp[ 1 ] * 255 );
 108             *ptr++ = (unsigned char)( tmp[ 2 ] * 255 );
 109         }
 110     }
 111     glTexImage2D( GL_TEXTURE_CUBE_MAP_NEGATIVE_X_ARB,
 112                   0, GL_RGBA8, 32, 32, 0, GL_RGB, GL_UNSIGNED_BYTE, data );
 113
 114     ptr = data;
 115     for ( j = 0; j < size; j++ ) {
 116         for ( i = 0; i < size; i++ ) {
 117             sgVec3 tmp;
 118             sgSetVec3( tmp, ( i + offset - half_size ),
 119                             half_size,
 120                             ( j + offset - half_size ) );
 121             sgNormalizeVec3( tmp );
 122             sgScaleVec3( tmp, 0.5f );
 123             sgAddVec3( tmp, zero_normal );
 124
 125             *ptr++ = (unsigned char)( tmp[ 0 ] * 255 );
 126             *ptr++ = (unsigned char)( tmp[ 1 ] * 255 );
 127             *ptr++ = (unsigned char)( tmp[ 2 ] * 255 );
 128         }
 129     }
 130     glTexImage2D( GL_TEXTURE_CUBE_MAP_POSITIVE_Y_ARB,
 131                   0, GL_RGBA8, 32, 32, 0, GL_RGB, GL_UNSIGNED_BYTE, data );
 132
 133     ptr = data;
 134     for ( j = 0; j < size; j++ ) {
 135         for ( i = 0; i < size; i++ ) {
 136             sgVec3 tmp;
 137             sgSetVec3( tmp, ( i + offset - half_size ),
 138                             -half_size,
 139                             -( j + offset - half_size ) );
 140             sgNormalizeVec3( tmp );
 141             sgScaleVec3( tmp, 0.5f );
 142             sgAddVec3( tmp, zero_normal );
 143
 144             *ptr++ = (unsigned char)( tmp[ 0 ] * 255 );
 145             *ptr++ = (unsigned char)( tmp[ 1 ] * 255 );
 146             *ptr++ = (unsigned char)( tmp[ 2 ] * 255 );
 147         }
 148     }
 149     glTexImage2D( GL_TEXTURE_CUBE_MAP_NEGATIVE_Y_ARB,
 150                   0, GL_RGBA8, 32, 32, 0, GL_RGB, GL_UNSIGNED_BYTE, data );
 151
 152     ptr = data;
 153     for ( j = 0; j < size; j++ ) {
 154         for ( i = 0; i < size; i++ ) {
 155             sgVec3 tmp;
 156             sgSetVec3( tmp, ( i + offset - half_size ),
 157                             -( j + offset - half_size ),
 158                             half_size );
 159             sgNormalizeVec3( tmp );
 160             sgScaleVec3( tmp, 0.5f );
 161             sgAddVec3( tmp, zero_normal );
 162
 163             *ptr++ = (unsigned char)( tmp[ 0 ] * 255 );
 164             *ptr++ = (unsigned char)( tmp[ 1 ] * 255 );
 165             *ptr++ = (unsigned char)( tmp[ 2 ] * 255 );
 166         }
 167     }
 168     glTexImage2D( GL_TEXTURE_CUBE_MAP_POSITIVE_Z_ARB,
 169                   0, GL_RGBA8, 32, 32, 0, GL_RGB, GL_UNSIGNED_BYTE, data );
 170
 171     ptr = data;
 172     for ( j = 0; j < size; j++ ) {
 173         for ( i = 0; i < size; i++ ) {
 174             sgVec3 tmp;
 175             sgSetVec3( tmp, -( i + offset - half_size ),
 176                             -( j + offset - half_size ),
 177                             -half_size );
 178             sgNormalizeVec3( tmp );
 179             sgScaleVec3( tmp, 0.5f );
 180             sgAddVec3( tmp, zero_normal );
 181
 182             *ptr++ = (unsigned char)( tmp[ 0 ] * 255 );
 183             *ptr++ = (unsigned char)( tmp[ 1 ] * 255 );
 184             *ptr++ = (unsigned char)( tmp[ 2 ] * 255 );
 185         }
 186     }
 187     glTexImage2D( GL_TEXTURE_CUBE_MAP_NEGATIVE_Z_ARB,
 188                   0, GL_RGBA8, 32, 32, 0, GL_RGB, GL_UNSIGNED_BYTE, data );
 189 }
 190
 191
 192 // Constructor
 193 SGCloudLayer::SGCloudLayer( const string &tex_path ) :
 194     layer_root(new ssgRoot),
 195     layer_transform(new ssgTransform),
 196     state_sel(0),
 197     texture_path(tex_path),
 198     layer_span(0.0),
 199     layer_asl(0.0),
 200     layer_thickness(0.0),
 201     layer_transition(0.0),
 202     layer_coverage(SG_CLOUD_CLEAR),
 203     scale(4000.0),
 204     speed(0.0),
 205     direction(0.0),
 206     last_lon(0.0),
 207     last_lat(0.0),
 208     vertices(0),
 209     indices(0)
 210 {
 211     cl[0] = cl[1] = cl[2] = cl[3] = NULL;
 212     vl[0] = vl[1] = vl[2] = vl[3] = NULL;
 213     tl[0] = tl[1] = tl[2] = tl[3] = NULL;
 214     layer[0] = layer[1] = layer[2] = layer[3] = NULL;
 215
 216     layer_root->addKid(layer_transform);
 217     rebuild();
 218 }
 219
 220 // Destructor
 221 SGCloudLayer::~SGCloudLayer()
 222 {
 223     delete vertices;
 224     delete indices;
 225     delete layer_root;          // deletes layer_transform and layer as well
 226 }
 227
 228 float
 229 SGCloudLayer::getSpan_m () const
 230 {
 231     return layer_span;
 232 }
 233
 234 void
 235 SGCloudLayer::setSpan_m (float span_m)
 236 {
 237     if (span_m != layer_span) {
 238         layer_span = span_m;
 239         rebuild();
 240     }
 241 }
 242
 243 float
 244 SGCloudLayer::getElevation_m () const
 245 {
 246     return layer_asl;
 247 }
 248
 249 void
 250 SGCloudLayer::setElevation_m (float elevation_m, bool set_span)
 251 {
 252     layer_asl = elevation_m;
 253
 254     if (set_span) {
 255         if (elevation_m > 4000)
 256             setSpan_m(  elevation_m * 10 );
 257         else
 258             setSpan_m( 40000 );
 259     }
 260 }
 261
 262 float
 263 SGCloudLayer::getThickness_m () const
 264 {
 265     return layer_thickness;
 266 }
 267
 268 void
 269 SGCloudLayer::setThickness_m (float thickness_m)
 270 {
 271     layer_thickness = thickness_m;
 272 }
 273
 274 float
 275 SGCloudLayer::getTransition_m () const
 276 {
 277     return layer_transition;
 278 }
 279
 280 void
 281 SGCloudLayer::setTransition_m (float transition_m)
 282 {
 283     layer_transition = transition_m;
 284 }
 285
 286 SGCloudLayer::Coverage
 287 SGCloudLayer::getCoverage () const
 288 {
 289     return layer_coverage;
 290 }
 291
 292 void
 293 SGCloudLayer::setCoverage (Coverage coverage)
 294 {
 295     if (coverage != layer_coverage) {
 296         layer_coverage = coverage;
 297         rebuild();
 298     }
 299 }
 300
 301
 302 // build the cloud object
 303 void
 304 SGCloudLayer::rebuild()
 305 {
 306     // Initialize states and sizes if necessary.
 307     if ( !state_initialized ) {
 308         state_initialized = true;
 309
 310         SG_LOG(SG_ASTRO, SG_INFO, "initializing cloud layers");
 311
 312         bump_mapping = SGIsOpenGLExtensionSupported("GL_ARB_multitexture") &&
 313                        SGIsOpenGLExtensionSupported("GL_ARB_texture_cube_map") &&
 314                        SGIsOpenGLExtensionSupported("GL_ARB_texture_env_combine") &&
 315                        SGIsOpenGLExtensionSupported("GL_ARB_texture_env_dot3") &&
 316                        SGIsOpenGLExtensionSupported("GL_ARB_imaging");
 317
 318         if ( bump_mapping ) {
 319             glGetIntegerv( GL_MAX_TEXTURE_UNITS_ARB, &nb_texture_unit );
 320             if ( nb_texture_unit < 2 ) {
 321                 bump_mapping = false;
 322             }
 323             nb_texture_unit = 2; // Force the number of units for now
 324         }
 325
 326         if ( bump_mapping ) {
 327
 328             // This bump mapping code was inspired by the tutorial available at
 329             // http://www.paulsprojects.net/tutorials/simplebump/simplebump.html
 330             // and a NVidia white paper
 331             //  http://developer.nvidia.com/object/bumpmappingwithregistercombiners.html
 332             // The normal map textures were generated by the normal map Gimp plugin :
 333             //  http://nifelheim.dyndns.org/~cocidius/normalmap/
 334             //
 335             SGPath cloud_path;
 336
 337             glActiveTexturePtr = (glActiveTextureProc)SGLookupFunction("glActiveTextureARB");
 338             glClientActiveTexturePtr = (glClientActiveTextureProc)SGLookupFunction("glClientActiveTextureARB");
 339             glBlendColorPtr = (glBlendColorProc)SGLookupFunction("glBlendColor");
 340
 341             cloud_path.set(texture_path.str());
 342             cloud_path.append("overcast.rgb");
 343             color_map[ SG_CLOUD_OVERCAST ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 344             color_map[ SG_CLOUD_OVERCAST ][ 0 ]->ref();
 345             cloud_path.set(texture_path.str());
 346             cloud_path.append("overcast_n.rgb");
 347             normal_map[ SG_CLOUD_OVERCAST ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 348             normal_map[ SG_CLOUD_OVERCAST ][ 0 ]->ref();
 349
 350             cloud_path.set(texture_path.str());
 351             cloud_path.append("overcast_top.rgb");
 352             color_map[ SG_CLOUD_OVERCAST ][ 1 ] = new ssgTexture( cloud_path.str().c_str() );
 353             color_map[ SG_CLOUD_OVERCAST ][ 1 ]->ref();
 354             cloud_path.set(texture_path.str());
 355             cloud_path.append("overcast_top_n.rgb");
 356             normal_map[ SG_CLOUD_OVERCAST ][ 1 ] = new ssgTexture( cloud_path.str().c_str() );
 357             normal_map[ SG_CLOUD_OVERCAST ][ 1 ]->ref();
 358
 359             cloud_path.set(texture_path.str());
 360             cloud_path.append("broken.rgba");
 361             color_map[ SG_CLOUD_BROKEN ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 362             color_map[ SG_CLOUD_BROKEN ][ 0 ]->ref();
 363             cloud_path.set(texture_path.str());
 364             cloud_path.append("broken_n.rgb");
 365             normal_map[ SG_CLOUD_BROKEN ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 366             normal_map[ SG_CLOUD_BROKEN ][ 0 ]->ref();
 367
 368             cloud_path.set(texture_path.str());
 369             cloud_path.append("scattered.rgba");
 370             color_map[ SG_CLOUD_SCATTERED ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 371             color_map[ SG_CLOUD_SCATTERED ][ 0 ]->ref();
 372             cloud_path.set(texture_path.str());
 373             cloud_path.append("scattered_n.rgb");
 374             normal_map[ SG_CLOUD_SCATTERED ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 375             normal_map[ SG_CLOUD_SCATTERED ][ 0 ]->ref();
 376
 377             cloud_path.set(texture_path.str());
 378             cloud_path.append("few.rgba");
 379             color_map[ SG_CLOUD_FEW ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 380             color_map[ SG_CLOUD_FEW ][ 0 ]->ref();
 381             cloud_path.set(texture_path.str());
 382             cloud_path.append("few_n.rgb");
 383             normal_map[ SG_CLOUD_FEW ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 384             normal_map[ SG_CLOUD_FEW ][ 0 ]->ref();
 385
 386             cloud_path.set(texture_path.str());
 387             cloud_path.append("cirrus.rgba");
 388             color_map[ SG_CLOUD_CIRRUS ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 389             color_map[ SG_CLOUD_CIRRUS ][ 0 ]->ref();
 390             cloud_path.set(texture_path.str());
 391             cloud_path.append("cirrus_n.rgb");
 392             normal_map[ SG_CLOUD_CIRRUS ][ 0 ] = new ssgTexture( cloud_path.str().c_str() );
 393             normal_map[ SG_CLOUD_CIRRUS ][ 0 ]->ref();
 394
 395             glGenTextures( 1, &normalization_cube_map );
 396             glBindTexture( GL_TEXTURE_CUBE_MAP_ARB, normalization_cube_map );
 397             generateNormalizationCubeMap();
 398             glTexParameteri( GL_TEXTURE_CUBE_MAP_ARB, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
 399             glTexParameteri( GL_TEXTURE_CUBE_MAP_ARB, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
 400             glTexParameteri( GL_TEXTURE_CUBE_MAP_ARB, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );
 401             glTexParameteri( GL_TEXTURE_CUBE_MAP_ARB, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE );
 402             glTexParameteri( GL_TEXTURE_CUBE_MAP_ARB, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE );
 403         } /* else */ {
 404             SGPath cloud_path;
 405             ssgStateSelector *state_sel;
 406             ssgSimpleState *state;
 407
 408             state_sel = new ssgStateSelector( 2 );
 409             state_sel->ref();
 410             cloud_path.set(texture_path.str());
 411             cloud_path.append("overcast.rgb");
 412             state_sel->setStep( 0, sgCloudMakeState(cloud_path.str()) );
 413             cloud_path.set(texture_path.str());
 414             cloud_path.append("overcast_top.rgb");
 415             state_sel->setStep( 1, sgCloudMakeState(cloud_path.str()) );
 416             layer_states[SG_CLOUD_OVERCAST] = state_sel;
 417
 418             state_sel = new ssgStateSelector( 2 );
 419             state_sel->ref();
 420             cloud_path.set(texture_path.str());
 421             cloud_path.append("broken.rgba");
 422             state = sgCloudMakeState(cloud_path.str());
 423             state_sel->setStep( 0, state );
 424             state_sel->setStep( 1, state );
 425             layer_states[SG_CLOUD_BROKEN] = state_sel;
 426
 427             state_sel = new ssgStateSelector( 2 );
 428             state_sel->ref();
 429             cloud_path.set(texture_path.str());
 430             cloud_path.append("scattered.rgba");
 431             state = sgCloudMakeState(cloud_path.str());
 432             state_sel->setStep( 0, state );
 433             state_sel->setStep( 1, state );
 434             layer_states[SG_CLOUD_SCATTERED] = state_sel;
 435
 436             state_sel = new ssgStateSelector( 2 );
 437             state_sel->ref();
 438             cloud_path.set(texture_path.str());
 439             cloud_path.append("few.rgba");
 440             state = sgCloudMakeState(cloud_path.str());
 441             state_sel->setStep( 0, state );
 442             state_sel->setStep( 1, state );
 443             layer_states[SG_CLOUD_FEW] = state_sel;
 444
 445             state_sel = new ssgStateSelector( 2 );
 446             state_sel->ref();
 447             cloud_path.set(texture_path.str());
 448             cloud_path.append("cirrus.rgba");
 449             state = sgCloudMakeState(cloud_path.str());
 450             state_sel->setStep( 0, state );
 451             state_sel->setStep( 1, state );
 452             layer_states[SG_CLOUD_CIRRUS] = state_sel;
 453
 454             layer_states[SG_CLOUD_CLEAR] = 0;
 455         }
 456     }
 457
 458     if ( bump_mapping ) {
 459
 460         if ( !vertices ) {
 461             vertices = new CloudVertex[ 25 ];
 462             indices = new unsigned int[ 40 ];
 463         }
 464
 465         sgVec2 base;
 466         sgSetVec2( base, sg_random(), sg_random() );
 467
 468         const float layer_scale = layer_span / scale;
 469         const float layer_to_core = (SG_EARTH_RAD * 1000 + layer_asl);
 470         const float half_angle = 0.5 * layer_span / layer_to_core;
 471
 472         int i;
 473         for ( i = -2; i <= 2; i++ ) {
 474             for ( int j = -2; j <= 2; j++ ) {
 475                 CloudVertex &v1 = vertices[ (i+2)*5 + (j+2) ];
 476                 sgSetVec3( v1.position,
 477                            0.5 * i * layer_span,
 478                            0.5 * j * layer_span,
 479                            -layer_to_core * ( 1 - cos( i * half_angle ) * cos( j * half_angle ) ) );
 480                 sgSetVec2( v1.texCoord,
 481                            base[0] + layer_scale * i * 0.25,
 482                            base[1] + layer_scale * j * 0.25 );
 483                 sgSetVec3( v1.sTangent,
 484                            cos( i * half_angle ),
 485                            0.f,
 486                            -sin( i * half_angle ) );
 487                 sgSetVec3( v1.tTangent,
 488                            0.f,
 489                            cos( j * half_angle ),
 490                            -sin( j * half_angle ) );
 491                 sgVectorProductVec3( v1.normal, v1.tTangent, v1.sTangent );
 492                 sgSetVec4( v1.color, 1.0f, 1.0f, 1.0f, (i == 0) ? 0.0f : 0.15f );
 493             }
 494         }
 495         /*
 496          * 0 1 5 6 10 11 15 16 20 21
 497          * 1 2 6 7 11 12 16 17 21 22
 498          * 2 3 7 8 12 13 17 18 22 23
 499          * 3 4 8 9 13 14 18 19 23 24
 500          */
 501         for ( i = 0; i < 4; i++ ) {
 502             for ( int j = 0; j < 5; j++ ) {
 503                 indices[ i*10 + (j*2) ]     =     i + 5 * j;
 504                 indices[ i*10 + (j*2) + 1 ] = 1 + i + 5 * j;
 505             }
 506         }
 507
 508     } /* else */ {
 509
 510         scale = 4000.0;
 511         last_lon = last_lat = -999.0f;
 512
 513         sgVec2 base;
 514         sgSetVec2( base, sg_random(), sg_random() );
 515
 516         // build the cloud layer
 517         sgVec4 color;
 518         sgVec3 vertex;
 519         sgVec2 tc;
 520
 521         const float layer_scale = layer_span / scale;
 522         const float mpi = SG_PI/4;
 523
 524         // caclculate the difference between a flat-earth model and
 525         // a round earth model given the span and altutude ASL of
 526         // the cloud layer. This is the difference in altitude between
 527         // the top of the inverted bowl and the edge of the bowl.
 528         // const float alt_diff = layer_asl * 0.8;
 529         const float layer_to_core = (SG_EARTH_RAD * 1000 + layer_asl);
 530         const float layer_angle = 0.5*layer_span / layer_to_core; // The angle is half the span
 531         const float border_to_core = layer_to_core * cos(layer_angle);
 532         const float alt_diff = layer_to_core - border_to_core;
 533
 534         for (int i = 0; i < 4; i++)
 535         {
 536             if ( layer[i] != NULL ) {
 537                 layer_transform->removeKid(layer[i]); // automatic delete
 538             }
 539
 540             vl[i] = new ssgVertexArray( 10 );
 541             cl[i] = new ssgColourArray( 10 );
 542             tl[i] = new ssgTexCoordArray( 10 );
 543
 544
 545             sgSetVec3( vertex, layer_span*(i-2)/2, -layer_span,
 546                             alt_diff * (sin(i*mpi) - 2) );
 547
 548             sgSetVec2( tc, base[0] + layer_scale * i/4, base[1] );
 549
 550             sgSetVec4( color, 1.0f, 1.0f, 1.0f, (i == 0) ? 0.0f : 0.15f );
 551
 552             cl[i]->add( color );
 553             vl[i]->add( vertex );
 554             tl[i]->add( tc );
 555
 556             for (int j = 0; j < 4; j++)
 557             {
 558                 sgSetVec3( vertex, layer_span*(i-1)/2, layer_span*(j-2)/2,
 559                                 alt_diff * (sin((i+1)*mpi) + sin(j*mpi) - 2) );
 560
 561                 sgSetVec2( tc, base[0] + layer_scale * (i+1)/4,
 562                             base[1] + layer_scale * j/4 );
 563
 564                 sgSetVec4( color, 1.0f, 1.0f, 1.0f,
 565                                 ( (j == 0) || (i == 3)) ?
 566                                 ( (j == 0) && (i == 3)) ? 0.0f : 0.15f : 1.0f );
 567
 568                 cl[i]->add( color );
 569                 vl[i]->add( vertex );
 570                 tl[i]->add( tc );
 571
 572
 573                 sgSetVec3( vertex, layer_span*(i-2)/2, layer_span*(j-1)/2,
 574                                 alt_diff * (sin(i*mpi) + sin((j+1)*mpi) - 2) );
 575
 576                 sgSetVec2( tc, base[0] + layer_scale * i/4,
 577                             base[1] + layer_scale * (j+1)/4 );
 578
 579                 sgSetVec4( color, 1.0f, 1.0f, 1.0f,
 580                                 ((j == 3) || (i == 0)) ?
 581                                 ((j == 3) && (i == 0)) ? 0.0f : 0.15f : 1.0f );
 582                 cl[i]->add( color );
 583                 vl[i]->add( vertex );
 584                 tl[i]->add( tc );
 585             }
 586
 587             sgSetVec3( vertex, layer_span*(i-1)/2, layer_span,
 588                             alt_diff * (sin((i+1)*mpi) - 2) );
 589
 590             sgSetVec2( tc, base[0] + layer_scale * (i+1)/4,
 591                         base[1] + layer_scale );
 592
 593             sgSetVec4( color, 1.0f, 1.0f, 1.0f, (i == 3) ? 0.0f : 0.15f );
 594
 595             cl[i]->add( color );
 596             vl[i]->add( vertex );
 597             tl[i]->add( tc );
 598
 599             layer[i] = new ssgVtxTable(GL_TRIANGLE_STRIP, vl[i], NULL, tl[i], cl[i]);
 600             layer_transform->addKid( layer[i] );
 601
 602             if ( layer_states[layer_coverage] != NULL ) {
 603                 layer[i]->setState( layer_states[layer_coverage] );
 604             }
 605             state_sel = layer_states[layer_coverage];
 606         }
 607
 608         // force a repaint of the sky colors with arbitrary defaults
 609         repaint( color );
 610     }
 611 }
 612
 613
 614 // repaint the cloud layer colors
 615 bool SGCloudLayer::repaint( sgVec3 fog_color ) {
 616
 617     if ( bump_mapping && enable_bump_mapping ) {
 618
 619         for ( int i = 0; i < 25; i++ ) {
 620             sgCopyVec3( vertices[ i ].color, fog_color );
 621         }
 622
 623     } else {
 624         float *color;
 625
 626         for ( int i = 0; i < 4; i++ ) {
 627             for ( int j = 0; j < 10; ++j ) {
 628                 color = cl[i]->get( j );
 629                 sgCopyVec3( color, fog_color );
 630             }
 631         }
 632     }
 633
 634     return true;
 635 }
 636
 637
 638 // reposition the cloud layer at the specified origin and orientation
 639 // lon specifies a rotation about the Z axis
 640 // lat specifies a rotation about the new Y axis
 641 // spin specifies a rotation about the new Z axis (and orients the
 642 // sunrise/set effects
 643 bool SGCloudLayer::reposition( sgVec3 p, sgVec3 up, double lon, double lat,
 644                                double alt, double dt )
 645 {
 646     sgMat4 T1, LON, LAT;
 647     sgVec3 axis;
 648
 649     // combine p and asl (meters) to get translation offset
 650     sgVec3 asl_offset;
 651     sgCopyVec3( asl_offset, up );
 652     sgNormalizeVec3( asl_offset );
 653     if ( alt <= layer_asl ) {
 654         sgScaleVec3( asl_offset, layer_asl );
 655     } else {
 656         sgScaleVec3( asl_offset, layer_asl + layer_thickness );
 657     }
 658     // cout << "asl_offset = " << asl_offset[0] << "," << asl_offset[1]
 659     //      << "," << asl_offset[2] << endl;
 660     sgAddVec3( asl_offset, p );
 661     // cout << "  asl_offset = " << asl_offset[0] << "," << asl_offset[1]
 662     //      << "," << asl_offset[2] << endl;
 663
 664     // Translate to zero elevation
 665     // Point3D zero_elev = current_view.get_cur_zero_elev();
 666     sgMakeTransMat4( T1, asl_offset );
 667
 668     // printf("  Translated to %.2f %.2f %.2f\n",
 669     //        zero_elev.x, zero_elev.y, zero_elev.z );
 670
 671     // Rotate to proper orientation
 672     // printf("  lon = %.2f  lat = %.2f\n",
 673     //        lon * SGD_RADIANS_TO_DEGREES,
 674     //        lat * SGD_RADIANS_TO_DEGREES);
 675     sgSetVec3( axis, 0.0, 0.0, 1.0 );
 676     sgMakeRotMat4( LON, lon * SGD_RADIANS_TO_DEGREES, axis );
 677
 678     sgSetVec3( axis, 0.0, 1.0, 0.0 );
 679     sgMakeRotMat4( LAT, 90.0 - lat * SGD_RADIANS_TO_DEGREES, axis );
 680
 681     sgMat4 TRANSFORM;
 682
 683     sgCopyMat4( TRANSFORM, T1 );
 684     sgPreMultMat4( TRANSFORM, LON );
 685     sgPreMultMat4( TRANSFORM, LAT );
 686
 687     sgCoord layerpos;
 688     sgSetCoord( &layerpos, TRANSFORM );
 689
 690     layer_transform->setTransform( &layerpos );
 691
 692     // now calculate update texture coordinates
 693     if ( last_lon < -900 ) {
 694         last_lon = lon;
 695         last_lat = lat;
 696     }
 697
 698     double sp_dist = speed*dt;
 699
 700     if ( lon != last_lon || lat != last_lat || sp_dist != 0 ) {
 701         Point3D start( last_lon, last_lat, 0.0 );
 702         Point3D dest( lon, lat, 0.0 );
 703         double course = 0.0, dist = 0.0;
 704
 705         calc_gc_course_dist( dest, start, &course, &dist );
 706         // cout << "course = " << course << ", dist = " << dist << endl;
 707
 708         // if start and dest are too close together,
 709         // calc_gc_course_dist() can return a course of "nan".  If
 710         // this happens, lets just use the last known good course.
 711         // This is a hack, and it would probably be better to make
 712         // calc_gc_course_dist() more robust.
 713         if ( isnan(course) ) {
 714             course = last_course;
 715         } else {
 716             last_course = course;
 717         }
 718
 719         // calculate cloud movement due to external forces
 720         double ax = 0.0, ay = 0.0, bx = 0.0, by = 0.0;
 721
 722         if (dist > 0.0) {
 723             ax = cos(course) * dist;
 724             ay = sin(course) * dist;
 725         }
 726
 727         if (sp_dist > 0) {
 728             bx = cos(-direction * SGD_DEGREES_TO_RADIANS) * sp_dist;
 729             by = sin(-direction * SGD_DEGREES_TO_RADIANS) * sp_dist;
 730         }
 731
 732
 733         double xoff = (ax + bx) / (2 * scale);
 734         double yoff = (ay + by) / (2 * scale);
 735
 736         const float layer_scale = layer_span / scale;
 737
 738         // cout << "xoff = " << xoff << ", yoff = " << yoff << endl;
 739
 740         float *base;
 741         if ( bump_mapping && enable_bump_mapping ) {
 742             base = vertices[12].texCoord;
 743         } else {
 744             base = tl[0]->get( 0 );
 745         }
 746         base[0] += xoff;
 747
 748         // the while loops can lead to *long* pauses if base[0] comes
 749         // with a bogus value.
 750         // while ( base[0] > 1.0 ) { base[0] -= 1.0; }
 751         // while ( base[0] < 0.0 ) { base[0] += 1.0; }
 752         if ( base[0] > -10.0 && base[0] < 10.0 ) {
 753             base[0] -= (int)base[0];
 754         } else {
 755             SG_LOG(SG_ASTRO, SG_DEBUG,
 756                 "Error: base = " << base[0] << "," << base[1] <<
 757                 " course = " << course << " dist = " << dist );
 758             base[0] = 0.0;
 759         }
 760
 761         base[1] += yoff;
 762         // the while loops can lead to *long* pauses if base[0] comes
 763         // with a bogus value.
 764         // while ( base[1] > 1.0 ) { base[1] -= 1.0; }
 765         // while ( base[1] < 0.0 ) { base[1] += 1.0; }
 766         if ( base[1] > -10.0 && base[1] < 10.0 ) {
 767             base[1] -= (int)base[1];
 768         } else {
 769             SG_LOG(SG_ASTRO, SG_ALERT,
 770                     "Error: base = " << base[0] << "," << base[1] <<
 771                     " course = " << course << " dist = " << dist );
 772             base[1] = 0.0;
 773         }
 774
 775         if ( bump_mapping && enable_bump_mapping ) {
 776
 777             for ( int i = -2; i <= 2; i++ ) {
 778                 for ( int j = -2; j <= 2; j++ ) {
 779                     if ( i == 0 && j == 0 )
 780                         continue; // Already done on base
 781                     CloudVertex &v1 = vertices[ (i+2)*5 + (j+2) ];
 782                     sgSetVec2( v1.texCoord,
 783                             base[0] + layer_scale * i * 0.25,
 784                             base[1] + layer_scale * j * 0.25 );
 785                 }
 786             }
 787
 788         } else {
 789                 // cout << "base = " << base[0] << "," << base[1] << endl;
 790
 791             float *tc;
 792             for (int i = 0; i < 4; i++) {
 793                 tc = tl[i]->get( 0 );
 794                 sgSetVec2( tc, base[0] + layer_scale * i/4, base[1] );
 795
 796                 for (int j = 0; j < 4; j++)
 797                 {
 798                     tc = tl[i]->get( j*2+1 );
 799                     sgSetVec2( tc, base[0] + layer_scale * (i+1)/4,
 800                                 base[1] + layer_scale * j/4 );
 801
 802                     tc = tl[i]->get( (j+1)*2 );
 803                     sgSetVec2( tc, base[0] + layer_scale * i/4,
 804                                 base[1] + layer_scale * (j+1)/4 );
 805                 }
 806
 807                 tc = tl[i]->get( 9 );
 808                 sgSetVec2( tc, base[0] + layer_scale * (i+1)/4,
 809                             base[1] + layer_scale );
 810             }
 811         }
 812
 813         last_lon = lon;
 814         last_lat = lat;
 815     }
 816
 817     return true;
 818 }
 819
 820
 821 void SGCloudLayer::draw( bool top ) {
 822     if ( layer_coverage != SG_CLOUD_CLEAR ) {
 823
 824         if ( bump_mapping && enable_bump_mapping ) {
 825
 826             sgMat4 modelview,
 827                    tmp,
 828                    transform;
 829             ssgGetModelviewMatrix( modelview );
 830             layer_transform->getTransform( transform );
 831
 832             sgInvertMat4( tmp, transform );
 833
 834             sgPostMultMat4( transform, modelview );
 835             ssgLoadModelviewMatrix( transform );
 836
 837             sgVec3 lightVec;
 838             ssgGetLight( 0 )->getPosition( lightVec );
 839             sgNegateVec3( lightVec );
 840             sgXformVec3( lightVec, tmp );
 841
 842             for ( int i = 0; i < 25; i++ ) {
 843                 CloudVertex &v = vertices[ i ];
 844                 sgSetVec3( v.tangentSpLight,
 845                            sgScalarProductVec3( v.sTangent, lightVec ),
 846                            sgScalarProductVec3( v.tTangent, lightVec ),
 847                            sgScalarProductVec3( v.normal, lightVec ) );
 848             }
 849
 850             ssgTexture *decal = color_map[ layer_coverage ][ top ? 1 : 0 ];
 851             if ( top && decal == 0 ) {
 852                 decal = color_map[ layer_coverage ][ 0 ];
 853             }
 854             ssgTexture *normal = normal_map[ layer_coverage ][ top ? 1 : 0 ];
 855             if ( top && normal == 0 ) {
 856                 normal = normal_map[ layer_coverage ][ 0 ];
 857             }
 858
 859             glDisable( GL_LIGHTING );
 860             glDisable( GL_CULL_FACE );
 861             if ( layer_coverage == SG_CLOUD_FEW ) {
 862                 glEnable( GL_ALPHA_TEST );
 863                 glAlphaFunc ( GL_GREATER, 0.01 );
 864             }
 865             glEnable( GL_BLEND );
 866             glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
 867
 868             glShadeModel( GL_SMOOTH );
 869             glEnable( GL_COLOR_MATERIAL );
 870             sgVec4 color;
 871             float emis = 0.05;
 872             if ( top ) {
 873                 ssgGetLight( 0 )->getColour( GL_DIFFUSE, color );
 874                 emis = ( color[0]+color[1]+color[2] ) / 3.0;
 875                 if ( emis < 0.05 )
 876                     emis = 0.05;
 877             }
 878             sgSetVec4( color, emis, emis, emis, 0.0 );
 879             glMaterialfv( GL_FRONT_AND_BACK, GL_EMISSION, color );
 880             sgSetVec4( color, 1.0f, 1.0f, 1.0f, 0.0 );
 881             glMaterialfv( GL_FRONT_AND_BACK, GL_AMBIENT, color );
 882             sgSetVec4( color, 0.5, 0.5, 0.5, 0.0 );
 883             glMaterialfv( GL_FRONT_AND_BACK, GL_DIFFUSE, color );
 884             sgSetVec4( color, 0.0, 0.0, 0.0, 0.0 );
 885             glMaterialfv( GL_FRONT_AND_BACK, GL_SPECULAR, color );
 886
 887             glActiveTexturePtr( GL_TEXTURE0_ARB );
 888             glBindTexture( GL_TEXTURE_2D, normal->getHandle() );
 889             glEnable( GL_TEXTURE_2D );
 890
 891             //Bind normalisation cube map to texture unit 1
 892             glActiveTexturePtr( GL_TEXTURE1_ARB );
 893             glBindTexture( GL_TEXTURE_CUBE_MAP_ARB, normalization_cube_map );
 894             glEnable( GL_TEXTURE_CUBE_MAP_ARB );
 895             glActiveTexturePtr( GL_TEXTURE0_ARB );
 896
 897             //Set vertex arrays for cloud
 898             glVertexPointer( 3, GL_FLOAT, sizeof(CloudVertex), &vertices[0].position );
 899             glEnableClientState( GL_VERTEX_ARRAY );
 900
 901             if ( nb_texture_unit >= 3 ) {
 902                 glColorPointer( 4, GL_FLOAT, sizeof(CloudVertex), &vertices[0].color );
 903                 glEnableClientState( GL_COLOR_ARRAY );
 904             }
 905
 906             //Send texture coords for normal map to unit 0
 907             glTexCoordPointer( 2, GL_FLOAT, sizeof(CloudVertex), &vertices[0].texCoord );
 908             glEnableClientState( GL_TEXTURE_COORD_ARRAY );
 909
 910             //Send tangent space light vectors for normalisation to unit 1
 911             glClientActiveTexturePtr( GL_TEXTURE1_ARB );
 912             glTexCoordPointer( 3, GL_FLOAT, sizeof(CloudVertex), &vertices[0].tangentSpLight );
 913             glEnableClientState( GL_TEXTURE_COORD_ARRAY );
 914
 915             //Set up texture environment to do (tex0 dot tex1)*color
 916             glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_ARB );
 917             glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_RGB_ARB, GL_TEXTURE );
 918             glTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_RGB_ARB, GL_REPLACE );
 919             glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_ALPHA_ARB, GL_TEXTURE );
 920             glTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_ALPHA_ARB, GL_REPLACE );
 921
 922             glActiveTexturePtr( GL_TEXTURE1_ARB );
 923
 924             glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_ARB );
 925             glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_RGB_ARB, GL_TEXTURE );
 926             glTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_RGB_ARB, GL_DOT3_RGB_ARB );
 927             glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE1_RGB_ARB, GL_PREVIOUS_ARB );
 928             glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_ALPHA_ARB, GL_PREVIOUS_ARB );
 929             glTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_ALPHA_ARB, GL_REPLACE );
 930
 931             if ( nb_texture_unit >= 3 ) {
 932                 glActiveTexturePtr( GL_TEXTURE2_ARB );
 933                 glBindTexture( GL_TEXTURE_2D, decal->getHandle() );
 934
 935                 glClientActiveTexturePtr( GL_TEXTURE2_ARB );
 936                 glTexCoordPointer( 2, GL_FLOAT, sizeof(CloudVertex), &vertices[0].texCoord );
 937                 glEnableClientState( GL_TEXTURE_COORD_ARRAY );
 938
 939                 sgVec4 factors;
 940                 if ( top || layer_coverage != SG_CLOUD_OVERCAST ) {
 941                     sgSetVec4( factors, 0.5f, 0.5f, 0.3f, 1.0f );
 942                 } else {
 943                     sgSetVec4( factors, 0.1f, 0.1f, 0.0f, 1.0f );
 944                 }
 945                 glTexEnvfv( GL_TEXTURE_ENV, GL_TEXTURE_ENV_COLOR, factors );
 946
 947                 glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_ARB );
 948                 glTexEnvi( GL_TEXTURE_ENV, GL_COMBINE_RGB_ARB, GL_INTERPOLATE_ARB );
 949                 glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE0_RGB_ARB, GL_TEXTURE );
 950                 glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE1_RGB_ARB, GL_PREVIOUS_ARB );
 951                 glTexEnvi( GL_TEXTURE_ENV, GL_SOURCE2_RGB_ARB, GL_CONSTANT_ARB );
 952
 953                 glClientActiveTexturePtr( GL_TEXTURE0_ARB );
 954                 glActiveTexturePtr( GL_TEXTURE0_ARB );
 955
 956                 //Draw cloud layer
 957                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[0] );
 958                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[10] );
 959                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[20] );
 960                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[30] );
 961
 962                 glDisable( GL_TEXTURE_2D );
 963                 glActiveTexturePtr( GL_TEXTURE1_ARB );
 964                 glDisable( GL_TEXTURE_CUBE_MAP_ARB );
 965                 glActiveTexturePtr( GL_TEXTURE2_ARB );
 966                 glDisable( GL_TEXTURE_2D );
 967                 glActiveTexturePtr( GL_TEXTURE0_ARB );
 968
 969                 glDisableClientState( GL_TEXTURE_COORD_ARRAY );
 970                 glClientActiveTexturePtr( GL_TEXTURE1_ARB );
 971                 glDisableClientState( GL_TEXTURE_COORD_ARRAY );
 972                 glClientActiveTexturePtr( GL_TEXTURE2_ARB );
 973                 glDisableClientState( GL_TEXTURE_COORD_ARRAY );
 974                 glClientActiveTexturePtr( GL_TEXTURE0_ARB );
 975
 976                 glDisableClientState( GL_COLOR_ARRAY );
 977                 glEnable( GL_LIGHTING );
 978
 979                 glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
 980
 981             } else {
 982                 glClientActiveTexturePtr( GL_TEXTURE0_ARB );
 983                 glActiveTexturePtr( GL_TEXTURE0_ARB );
 984
 985                 //Draw cloud layer
 986                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[0] );
 987                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[10] );
 988                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[20] );
 989                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[30] );
 990
 991                 //Disable textures
 992                 glDisable( GL_TEXTURE_2D );
 993
 994                 glActiveTexturePtr( GL_TEXTURE1_ARB );
 995                 glDisable( GL_TEXTURE_CUBE_MAP_ARB );
 996                 glActiveTexturePtr( GL_TEXTURE0_ARB );
 997
 998                 //disable vertex arrays
 999                 glDisableClientState( GL_VERTEX_ARRAY );
1000
1001                 glDisableClientState( GL_TEXTURE_COORD_ARRAY );
1002                 glClientActiveTexturePtr( GL_TEXTURE1_ARB );
1003                 glDisableClientState( GL_TEXTURE_COORD_ARRAY );
1004                 glClientActiveTexturePtr( GL_TEXTURE0_ARB );
1005
1006                 //Return to standard modulate texenv
1007                 glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
1008
1009                 glDepthFunc(GL_LEQUAL);
1010
1011                 glEnable( GL_LIGHTING );
1012                 sgVec4 color;
1013                 ssgGetLight( 0 )->getColour( GL_DIFFUSE, color );
1014                 float average = ( color[0] + color[1] + color[2] ) / 3.0f;
1015                 sgVec4 averageColor;
1016                 sgSetVec4( averageColor, average, average, average, 1.0f );
1017                 ssgGetLight( 0 )->setColour( GL_DIFFUSE, averageColor );
1018
1019                 glBlendColorPtr( average, average, average, 1.0f );
1020                 glBlendFunc( GL_ONE_MINUS_CONSTANT_COLOR, GL_CONSTANT_COLOR );
1021
1022                 //Perform a second pass to color the torus
1023                 //Bind decal texture
1024                 glBindTexture( GL_TEXTURE_2D, decal->getHandle() );
1025                 glEnable(GL_TEXTURE_2D);
1026
1027                 //Set vertex arrays for torus
1028                 glVertexPointer( 3, GL_FLOAT, sizeof(CloudVertex), &vertices[0].position );
1029                 glEnableClientState( GL_VERTEX_ARRAY );
1030
1031                 //glColorPointer( 4, GL_FLOAT, sizeof(CloudVertex), &vertices[0].color );
1032                 //glEnableClientState( GL_COLOR_ARRAY );
1033
1034                 glNormalPointer( GL_FLOAT, sizeof(CloudVertex), &vertices[0].normal );
1035                 glEnableClientState( GL_NORMAL_ARRAY );
1036
1037                 glTexCoordPointer( 2, GL_FLOAT, sizeof(CloudVertex), &vertices[0].texCoord );
1038                 glEnableClientState( GL_TEXTURE_COORD_ARRAY );
1039
1040                 //Draw cloud layer
1041                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[0] );
1042                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[10] );
1043                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[20] );
1044                 glDrawElements( GL_TRIANGLE_STRIP, 10, GL_UNSIGNED_INT, &indices[30] );
1045
1046                 ssgGetLight( 0 )->setColour( GL_DIFFUSE, color );
1047
1048                 glDisableClientState( GL_TEXTURE_COORD_ARRAY );
1049             }
1050             //Disable texture
1051             glDisable( GL_TEXTURE_2D );
1052
1053             glDisableClientState( GL_VERTEX_ARRAY );
1054             glDisableClientState( GL_NORMAL_ARRAY );
1055
1056             glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
1057             glEnable( GL_CULL_FACE );
1058             glDepthFunc(GL_LESS);
1059
1060             ssgLoadModelviewMatrix( modelview );
1061
1062         } else {
1063             state_sel->selectStep( top ? 1 : 0 );
1064             ssgCullAndDraw( layer_root );
1065         }
1066     }
1067 }
1068
1069
1070 // make an ssgSimpleState for a cloud layer given the named texture
1071 ssgSimpleState *sgCloudMakeState( const string &path ) {
1072     ssgSimpleState *state = new ssgSimpleState();
1073
1074     SG_LOG(SG_ASTRO, SG_INFO, " texture = ");
1075
1076     state->setTexture( (char *)path.c_str() );
1077     state->setShadeModel( GL_SMOOTH );
1078     state->disable( GL_LIGHTING );
1079     state->disable( GL_CULL_FACE );
1080     state->enable( GL_TEXTURE_2D );
1081     state->enable( GL_COLOR_MATERIAL );
1082     state->setColourMaterial( GL_AMBIENT_AND_DIFFUSE );
1083     state->setMaterial( GL_EMISSION, 0.05, 0.05, 0.05, 0.0 );
1084     state->setMaterial( GL_AMBIENT, 0.2, 0.2, 0.2, 0.0 );
1085     state->setMaterial( GL_DIFFUSE, 0.5, 0.5, 0.5, 0.0 );
1086     state->setMaterial( GL_SPECULAR, 0.0, 0.0, 0.0, 0.0 );
1087     state->enable( GL_BLEND );
1088     state->enable( GL_ALPHA_TEST );
1089     state->setAlphaClamp( 0.01 );
1090
1091     return state;
1092 }