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 library is free software; you can redistribute it and/or
   8 // modify it under the terms of the GNU Library General Public
   9 // License as published by the Free Software Foundation; either
  10 // version 2 of the License, or (at your option) any later version.
  11 //
  12 // This library is distributed in the hope that it will be useful, but
  13 // WITHOUT ANY WARRANTY; without even the implied warranty of
  14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15 // General Public License for more details.
  16 //
  17 // You should have received a copy of the GNU General Public License
  18 // along with this program; if not, write to the Free Software
  19 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  20 //
  21
  22 #ifdef HAVE_CONFIG_H
  23 #  include <simgear_config.h>
  24 #endif
  25
  26 #include <simgear/compiler.h>
  27
  28 #include <sstream>
  29
  30 #include <math.h>
  31
  32 #include <simgear/structure/OSGVersion.hxx>
  33 #include <osg/AlphaFunc>
  34 #include <osg/BlendFunc>
  35 #include <osg/CullFace>
  36 #include <osg/Geode>
  37 #include <osg/Geometry>
  38 #include <osg/Material>
  39 #include <osg/ShadeModel>
  40 #include <osg/TexEnv>
  41 #include <osg/TexEnvCombine>
  42 #include <osg/Texture2D>
  43 #include <osg/TexMat>
  44 #include <osg/Fog>
  45
  46 #include <simgear/math/sg_random.h>
  47 #include <simgear/scene/util/SGReaderWriterOptions.hxx>
  48 #include <simgear/debug/logstream.hxx>
  49 #include <simgear/scene/model/model.hxx>
  50 #include <simgear/scene/util/RenderConstants.hxx>
  51 #include <simgear/scene/util/OsgMath.hxx>
  52 #include <simgear/scene/util/StateAttributeFactory.hxx>
  53 #include <simgear/screen/extensions.hxx>
  54
  55 #include "newcloud.hxx"
  56 #include "cloudfield.hxx"
  57 #include "cloud.hxx"
  58
  59 using namespace simgear;
  60 using namespace osg;
  61
  62 static osg::ref_ptr<osg::StateSet> layer_states[SGCloudLayer::SG_MAX_CLOUD_COVERAGES];
  63 static osg::ref_ptr<osg::StateSet> layer_states2[SGCloudLayer::SG_MAX_CLOUD_COVERAGES];
  64 static bool state_initialized = false;
  65
  66 const std::string SGCloudLayer::SG_CLOUD_OVERCAST_STRING = "overcast";
  67 const std::string SGCloudLayer::SG_CLOUD_BROKEN_STRING = "broken";
  68 const std::string SGCloudLayer::SG_CLOUD_SCATTERED_STRING = "scattered";
  69 const std::string SGCloudLayer::SG_CLOUD_FEW_STRING = "few";
  70 const std::string SGCloudLayer::SG_CLOUD_CIRRUS_STRING = "cirrus";
  71 const std::string SGCloudLayer::SG_CLOUD_CLEAR_STRING = "clear";
  72
  73 // make an StateSet for a cloud layer given the named texture
  74 static osg::StateSet*
  75 SGMakeState(const SGPath &path, const char* colorTexture,
  76             const char* normalTexture)
  77 {
  78     osg::StateSet *stateSet = new osg::StateSet;
  79
  80     osg::ref_ptr<SGReaderWriterOptions> options;
  81     options = SGReaderWriterOptions::fromPath(path.str());
  82     stateSet->setTextureAttribute(0, SGLoadTexture2D(colorTexture,
  83                                                      options.get()));
  84     stateSet->setTextureMode(0, GL_TEXTURE_2D, osg::StateAttribute::ON);
  85     StateAttributeFactory* attribFactory = StateAttributeFactory::instance();
  86     stateSet->setAttributeAndModes(attribFactory->getSmoothShadeModel());
  87     stateSet->setMode(GL_LIGHTING, osg::StateAttribute::OFF);
  88     stateSet->setAttributeAndModes(attribFactory->getStandardAlphaFunc());
  89     stateSet->setAttributeAndModes(attribFactory->getStandardBlendFunc());
  90     stateSet->setMode(GL_FOG, osg::StateAttribute::OFF);
  91
  92     return stateSet;
  93 }
  94
  95 // Constructor
  96 SGCloudLayer::SGCloudLayer( const string &tex_path ) :
  97     cloud_root(new osg::Switch),
  98     layer_root(new osg::Switch),
  99     group_top(new osg::Group),
 100     group_bottom(new osg::Group),
 101     layer_transform(new osg::MatrixTransform),
 102     cloud_alpha(1.0),
 103     texture_path(tex_path),
 104     layer_span(0.0),
 105     layer_asl(0.0),
 106     layer_thickness(0.0),
 107     layer_transition(0.0),
 108     layer_visibility(25.0),
 109     layer_coverage(SG_CLOUD_CLEAR),
 110     scale(4000.0),
 111     speed(0.0),
 112     direction(0.0),
 113     last_course(0.0),
 114     max_alpha(1.0)
 115 {
 116     // XXX
 117     // Render bottoms before the rest of transparent objects (rendered
 118     // in bin 10), tops after. The negative numbers on the bottoms
 119     // RenderBins and the positive numbers on the tops enforce this
 120     // order.
 121   cloud_root->addChild(layer_root.get(), true);
 122   layer_root->addChild(group_bottom.get());
 123   layer_root->addChild(group_top.get());
 124   osg::StateSet *rootSet = layer_root->getOrCreateStateSet();
 125   rootSet->setRenderBinDetails(CLOUDS_BIN, "DepthSortedBin");
 126   rootSet->setTextureAttribute(0, new osg::TexMat);
 127   rootSet->setMode(GL_CULL_FACE, osg::StateAttribute::ON);
 128   // Combiner for fog color and cloud alpha
 129   osg::TexEnvCombine* combine0 = new osg::TexEnvCombine;
 130   osg::TexEnvCombine* combine1 = new osg::TexEnvCombine;
 131   combine0->setCombine_RGB(osg::TexEnvCombine::MODULATE);
 132   combine0->setSource0_RGB(osg::TexEnvCombine::PREVIOUS);
 133   combine0->setOperand0_RGB(osg::TexEnvCombine::SRC_COLOR);
 134   combine0->setSource1_RGB(osg::TexEnvCombine::TEXTURE0);
 135   combine0->setOperand1_RGB(osg::TexEnvCombine::SRC_COLOR);
 136   combine0->setCombine_Alpha(osg::TexEnvCombine::MODULATE);
 137   combine0->setSource0_Alpha(osg::TexEnvCombine::PREVIOUS);
 138   combine0->setOperand0_Alpha(osg::TexEnvCombine::SRC_ALPHA);
 139   combine0->setSource1_Alpha(osg::TexEnvCombine::TEXTURE0);
 140   combine0->setOperand1_Alpha(osg::TexEnvCombine::SRC_ALPHA);
 141
 142   combine1->setCombine_RGB(osg::TexEnvCombine::MODULATE);
 143   combine1->setSource0_RGB(osg::TexEnvCombine::PREVIOUS);
 144   combine1->setOperand0_RGB(osg::TexEnvCombine::SRC_COLOR);
 145   combine1->setSource1_RGB(osg::TexEnvCombine::CONSTANT);
 146   combine1->setOperand1_RGB(osg::TexEnvCombine::SRC_COLOR);
 147   combine1->setCombine_Alpha(osg::TexEnvCombine::MODULATE);
 148   combine1->setSource0_Alpha(osg::TexEnvCombine::PREVIOUS);
 149   combine1->setOperand0_Alpha(osg::TexEnvCombine::SRC_ALPHA);
 150   combine1->setSource1_Alpha(osg::TexEnvCombine::CONSTANT);
 151   combine1->setOperand1_Alpha(osg::TexEnvCombine::SRC_ALPHA);
 152   combine1->setDataVariance(osg::Object::DYNAMIC);
 153   rootSet->setTextureAttributeAndModes(0, combine0);
 154   rootSet->setTextureAttributeAndModes(1, combine1);
 155   rootSet->setTextureMode(1, GL_TEXTURE_2D, osg::StateAttribute::ON);
 156   rootSet->setTextureAttributeAndModes(1, StateAttributeFactory::instance()
 157                                        ->getWhiteTexture(),
 158                                        osg::StateAttribute::ON);
 159   rootSet->setDataVariance(osg::Object::DYNAMIC);
 160
 161   // Ensure repeatability of the random seed within 10 minutes,
 162   // to keep multi-computer systems in sync.
 163   sg_srandom_time_10();
 164   base = osg::Vec2(sg_random(), sg_random());
 165   group_top->addChild(layer_transform.get());
 166   group_bottom->addChild(layer_transform.get());
 167
 168   layer3D = new SGCloudField();
 169   cloud_root->addChild(layer3D->getNode(), false);
 170
 171   rebuild();
 172 }
 173
 174 // Destructor
 175 SGCloudLayer::~SGCloudLayer()
 176 {
 177   delete layer3D;
 178 }
 179
 180 float
 181 SGCloudLayer::getSpan_m () const
 182 {
 183     return layer_span;
 184 }
 185
 186 void
 187 SGCloudLayer::setSpan_m (float span_m)
 188 {
 189     if (span_m != layer_span) {
 190         layer_span = span_m;
 191         rebuild();
 192     }
 193 }
 194
 195 float
 196 SGCloudLayer::getElevation_m () const
 197 {
 198     return layer_asl;
 199 }
 200
 201 void
 202 SGCloudLayer::setElevation_m (float elevation_m, bool set_span)
 203 {
 204     layer_asl = elevation_m;
 205
 206     if (set_span) {
 207         if (elevation_m > 4000)
 208             setSpan_m(  elevation_m * 10 );
 209         else
 210             setSpan_m( 40000 );
 211     }
 212 }
 213
 214 float
 215 SGCloudLayer::getThickness_m () const
 216 {
 217     return layer_thickness;
 218 }
 219
 220 void
 221 SGCloudLayer::setThickness_m (float thickness_m)
 222 {
 223     layer_thickness = thickness_m;
 224 }
 225
 226 float
 227 SGCloudLayer::getVisibility_m() const
 228 {
 229     return layer_visibility;
 230 }
 231
 232 void
 233 SGCloudLayer::setVisibility_m (float visibility_m)
 234 {
 235     layer_visibility = visibility_m;
 236 }
 237
 238 float
 239 SGCloudLayer::getTransition_m () const
 240 {
 241     return layer_transition;
 242 }
 243
 244 void
 245 SGCloudLayer::setTransition_m (float transition_m)
 246 {
 247     layer_transition = transition_m;
 248 }
 249
 250 SGCloudLayer::Coverage
 251 SGCloudLayer::getCoverage () const
 252 {
 253     return layer_coverage;
 254 }
 255
 256 void
 257 SGCloudLayer::setCoverage (Coverage coverage)
 258 {
 259     if (coverage != layer_coverage) {
 260         layer_coverage = coverage;
 261         rebuild();
 262     }
 263 }
 264
 265 const std::string &
 266 SGCloudLayer::getCoverageString( Coverage coverage )
 267 {
 268         switch( coverage ) {
 269                 case SG_CLOUD_OVERCAST:
 270                         return SG_CLOUD_OVERCAST_STRING;
 271                 case SG_CLOUD_BROKEN:
 272                         return SG_CLOUD_BROKEN_STRING;
 273                 case SG_CLOUD_SCATTERED:
 274                         return SG_CLOUD_SCATTERED_STRING;
 275                 case SG_CLOUD_FEW:
 276                         return SG_CLOUD_FEW_STRING;
 277                 case SG_CLOUD_CIRRUS:
 278                         return SG_CLOUD_CIRRUS_STRING;
 279                 case SG_CLOUD_CLEAR:
 280                 default:
 281                         return SG_CLOUD_CLEAR_STRING;
 282         }
 283 }
 284
 285 SGCloudLayer::Coverage
 286 SGCloudLayer::getCoverageType( const std::string & coverage )
 287 {
 288         if( SG_CLOUD_OVERCAST_STRING == coverage ) {
 289                 return SG_CLOUD_OVERCAST;
 290         } else if( SG_CLOUD_BROKEN_STRING == coverage ) {
 291                 return SG_CLOUD_BROKEN;
 292         } else if( SG_CLOUD_SCATTERED_STRING == coverage ) {
 293                 return SG_CLOUD_SCATTERED;
 294         } else if( SG_CLOUD_FEW_STRING == coverage ) {
 295                 return SG_CLOUD_FEW;
 296         } else if( SG_CLOUD_CIRRUS_STRING == coverage ) {
 297                 return SG_CLOUD_CIRRUS;
 298         } else {
 299                 return SG_CLOUD_CLEAR;
 300         }
 301 }
 302
 303 const std::string &
 304 SGCloudLayer::getCoverageString() const
 305 {
 306         return getCoverageString(layer_coverage);
 307 }
 308
 309 void
 310 SGCloudLayer::setCoverageString( const std::string & coverage )
 311 {
 312         setCoverage( getCoverageType(coverage) );
 313 }
 314
 315 void
 316 SGCloudLayer::setTextureOffset(const osg::Vec2& offset)
 317 {
 318     osg::StateAttribute* attr = layer_root->getStateSet()
 319         ->getTextureAttribute(0, osg::StateAttribute::TEXMAT);
 320     osg::TexMat* texMat = dynamic_cast<osg::TexMat*>(attr);
 321     if (!texMat)
 322         return;
 323     texMat->setMatrix(osg::Matrix::translate(offset[0], offset[1], 0.0));
 324 }
 325
 326 // colors for debugging the cloud layers
 327 #ifdef CLOUD_DEBUG
 328 Vec3 cloudColors[] = {Vec3(1.0f, 1.0f, 1.0f), Vec3(1.0f, 0.0f, 0.0f),
 329                       Vec3(0.0f, 1.0f, 0.0f), Vec3(0.0f, 0.0f, 1.0f)};
 330 #else
 331 Vec3 cloudColors[] = {Vec3(1.0f, 1.0f, 1.0f), Vec3(1.0f, 1.0f, 1.0f),
 332                       Vec3(1.0f, 1.0f, 1.0f), Vec3(1.0f, 1.0f, 1.0f)};
 333 #endif
 334
 335 // build the cloud object
 336 void
 337 SGCloudLayer::rebuild()
 338 {
 339     // Initialize states and sizes if necessary.
 340     if ( !state_initialized ) {
 341         state_initialized = true;
 342
 343         SG_LOG(SG_ASTRO, SG_INFO, "initializing cloud layers");
 344
 345         osg::StateSet* state;
 346         state = SGMakeState(texture_path, "overcast.png", "overcast_n.png");
 347         layer_states[SG_CLOUD_OVERCAST] = state;
 348         state = SGMakeState(texture_path, "overcast_top.png", "overcast_top_n.png");
 349         layer_states2[SG_CLOUD_OVERCAST] = state;
 350
 351         state = SGMakeState(texture_path, "broken.png", "broken_n.png");
 352         layer_states[SG_CLOUD_BROKEN] = state;
 353         layer_states2[SG_CLOUD_BROKEN] = state;
 354
 355         state = SGMakeState(texture_path, "scattered.png", "scattered_n.png");
 356         layer_states[SG_CLOUD_SCATTERED] = state;
 357         layer_states2[SG_CLOUD_SCATTERED] = state;
 358
 359         state = SGMakeState(texture_path, "few.png", "few_n.png");
 360         layer_states[SG_CLOUD_FEW] = state;
 361         layer_states2[SG_CLOUD_FEW] = state;
 362
 363         state = SGMakeState(texture_path, "cirrus.png", "cirrus_n.png");
 364         layer_states[SG_CLOUD_CIRRUS] = state;
 365         layer_states2[SG_CLOUD_CIRRUS] = state;
 366
 367         layer_states[SG_CLOUD_CLEAR] = 0;
 368         layer_states2[SG_CLOUD_CLEAR] = 0;
 369 #if 1
 370         // experimental optimization that may not make any difference
 371         // at all :/
 372         osg::CopyOp copyOp;
 373         for (int i = 0; i < SG_MAX_CLOUD_COVERAGES; ++i) {
 374             StateAttributeFactory *saf = StateAttributeFactory::instance();
 375             if (layer_states[i].valid()) {
 376                 if (layer_states[i] == layer_states2[i])
 377                     layer_states2[i] = static_cast<osg::StateSet*>(layer_states[i]->clone(copyOp));
 378                 layer_states[i]->setAttribute(saf ->getCullFaceFront());
 379                 layer_states2[i]->setAttribute(saf ->getCullFaceBack());
 380             }
 381         }
 382 #endif
 383     }
 384
 385     scale = 4000.0;
 386
 387     setTextureOffset(base);
 388     // build the cloud layer
 389     const float layer_scale = layer_span / scale;
 390     const float mpi = SG_PI/4;
 391
 392     // caclculate the difference between a flat-earth model and
 393     // a round earth model given the span and altutude ASL of
 394     // the cloud layer. This is the difference in altitude between
 395     // the top of the inverted bowl and the edge of the bowl.
 396     // const float alt_diff = layer_asl * 0.8;
 397     const float layer_to_core = (SG_EARTH_RAD * 1000 + layer_asl);
 398     const float layer_angle = 0.5*layer_span / layer_to_core; // The angle is half the span
 399     const float border_to_core = layer_to_core * cos(layer_angle);
 400     const float alt_diff = layer_to_core - border_to_core;
 401
 402     for (int i = 0; i < 4; i++) {
 403       if ( layer[i] != NULL ) {
 404         layer_transform->removeChild(layer[i].get()); // automatic delete
 405       }
 406
 407       vl[i] = new osg::Vec3Array;
 408       cl[i] = new osg::Vec4Array;
 409       tl[i] = new osg::Vec2Array;
 410
 411
 412       osg::Vec3 vertex(layer_span*(i-2)/2, -layer_span,
 413                        alt_diff * (sin(i*mpi) - 2));
 414       osg::Vec2 tc(layer_scale * i/4, 0.0f);
 415       osg::Vec4 color(cloudColors[0], (i == 0) ? 0.0f : 0.15f);
 416
 417       cl[i]->push_back(color);
 418       vl[i]->push_back(vertex);
 419       tl[i]->push_back(tc);
 420
 421       for (int j = 0; j < 4; j++) {
 422         vertex = osg::Vec3(layer_span*(i-1)/2, layer_span*(j-2)/2,
 423                            alt_diff * (sin((i+1)*mpi) + sin(j*mpi) - 2));
 424         tc = osg::Vec2(layer_scale * (i+1)/4, layer_scale * j/4);
 425         color = osg::Vec4(cloudColors[0],
 426                           ( (j == 0) || (i == 3)) ?
 427                           ( (j == 0) && (i == 3)) ? 0.0f : 0.15f : 1.0f );
 428
 429         cl[i]->push_back(color);
 430         vl[i]->push_back(vertex);
 431         tl[i]->push_back(tc);
 432
 433         vertex = osg::Vec3(layer_span*(i-2)/2, layer_span*(j-1)/2,
 434                            alt_diff * (sin(i*mpi) + sin((j+1)*mpi) - 2) );
 435         tc = osg::Vec2(layer_scale * i/4, layer_scale * (j+1)/4 );
 436         color = osg::Vec4(cloudColors[0],
 437                           ((j == 3) || (i == 0)) ?
 438                           ((j == 3) && (i == 0)) ? 0.0f : 0.15f : 1.0f );
 439         cl[i]->push_back(color);
 440         vl[i]->push_back(vertex);
 441         tl[i]->push_back(tc);
 442       }
 443
 444       vertex = osg::Vec3(layer_span*(i-1)/2, layer_span,
 445                          alt_diff * (sin((i+1)*mpi) - 2));
 446
 447       tc = osg::Vec2(layer_scale * (i+1)/4, layer_scale);
 448
 449       color = osg::Vec4(cloudColors[0], (i == 3) ? 0.0f : 0.15f );
 450
 451       cl[i]->push_back( color );
 452       vl[i]->push_back( vertex );
 453       tl[i]->push_back( tc );
 454
 455       osg::Geometry* geometry = new osg::Geometry;
 456       geometry->setUseDisplayList(false);
 457       geometry->setVertexArray(vl[i].get());
 458       geometry->setNormalBinding(osg::Geometry::BIND_OFF);
 459       geometry->setColorArray(cl[i].get(), osg::Array::BIND_PER_VERTEX);
 460       geometry->setTexCoordArray(0, tl[i].get(), osg::Array::BIND_PER_VERTEX);
 461       geometry->addPrimitiveSet(new osg::DrawArrays(GL_TRIANGLE_STRIP, 0, vl[i]->size()));
 462       layer[i] = new osg::Geode;
 463
 464       std::stringstream sstr;
 465       sstr << "Cloud Layer (" << i << ")";
 466       geometry->setName(sstr.str());
 467       layer[i]->setName(sstr.str());
 468       layer[i]->addDrawable(geometry);
 469       layer_transform->addChild(layer[i].get());
 470     }
 471
 472     //OSGFIXME: true
 473     if ( layer_states[layer_coverage].valid() ) {
 474       osg::CopyOp copyOp;    // shallow copy
 475       // render bin will be set in reposition
 476       osg::StateSet* stateSet = static_cast<osg::StateSet*>(layer_states2[layer_coverage]->clone(copyOp));
 477       stateSet->setDataVariance(osg::Object::DYNAMIC);
 478       group_top->setStateSet(stateSet);
 479       stateSet = static_cast<osg::StateSet*>(layer_states[layer_coverage]->clone(copyOp));
 480       stateSet->setDataVariance(osg::Object::DYNAMIC);
 481       group_bottom->setStateSet(stateSet);
 482     }
 483 }
 484
 485 // repaint the cloud layer colors
 486 bool SGCloudLayer::repaint( const SGVec3f& fog_color ) {
 487     osg::Vec4f combineColor(toOsg(fog_color), cloud_alpha);
 488     osg::TexEnvCombine* combiner
 489         = dynamic_cast<osg::TexEnvCombine*>(layer_root->getStateSet()
 490                                             ->getTextureAttribute(1, osg::StateAttribute::TEXENV));
 491     combiner->setConstantColor(combineColor);
 492
 493     // Set the fog color for the 3D clouds too.
 494     //cloud3dfog->setColor(combineColor);
 495     return true;
 496 }
 497
 498 // reposition the cloud layer at the specified origin and orientation
 499 // lon specifies a rotation about the Z axis
 500 // lat specifies a rotation about the new Y axis
 501 // spin specifies a rotation about the new Z axis (and orients the
 502 // sunrise/set effects
 503 bool SGCloudLayer::reposition( const SGVec3f& p,
 504                                const SGVec3f& up,
 505                                double lon,
 506                                double lat,
 507                                double alt,
 508                                double dt )
 509 {
 510
 511     if (getCoverage() != SGCloudLayer::SG_CLOUD_CLEAR)
 512     {
 513         // combine p and asl (meters) to get translation offset
 514         osg::Vec3 asl_offset(toOsg(up));
 515         asl_offset.normalize();
 516         if ( alt <= layer_asl ) {
 517             asl_offset *= layer_asl;
 518         } else {
 519             asl_offset *= layer_asl + layer_thickness;
 520         }
 521
 522         // cout << "asl_offset = " << asl_offset[0] << "," << asl_offset[1]
 523         //      << "," << asl_offset[2] << endl;
 524         asl_offset += toOsg(p);
 525         // cout << "  asl_offset = " << asl_offset[0] << "," << asl_offset[1]
 526         //      << "," << asl_offset[2] << endl;
 527
 528         osg::Matrix T, LON, LAT;
 529         // Translate to zero elevation
 530         // Point3D zero_elev = current_view.get_cur_zero_elev();
 531         T.makeTranslate( asl_offset );
 532
 533         // printf("  Translated to %.2f %.2f %.2f\n",
 534         //        zero_elev.x, zero_elev.y, zero_elev.z );
 535
 536         // Rotate to proper orientation
 537         // printf("  lon = %.2f  lat = %.2f\n",
 538         //        lon * SGD_RADIANS_TO_DEGREES,
 539         //        lat * SGD_RADIANS_TO_DEGREES);
 540         LON.makeRotate(lon, osg::Vec3(0, 0, 1));
 541
 542         // xglRotatef( 90.0 - f->get_Latitude() * SGD_RADIANS_TO_DEGREES,
 543         //             0.0, 1.0, 0.0 );
 544         LAT.makeRotate(90.0 * SGD_DEGREES_TO_RADIANS - lat, osg::Vec3(0, 1, 0));
 545
 546         layer_transform->setMatrix( LAT*LON*T );
 547
 548         // The layers need to be drawn in order because they are
 549         // translucent, but OSG transparency sorting doesn't work because
 550         // the cloud polys are huge. However, the ordering is simple: the
 551         // bottom polys should be drawn from high altitude to low, and the
 552         // top polygons from low to high. The altitude can be used
 553         // directly to order the polygons!
 554         group_bottom->getStateSet()->setRenderBinDetails(-(int)layer_asl,
 555                                                          "RenderBin");
 556         group_top->getStateSet()->setRenderBinDetails((int)layer_asl,
 557                                                       "RenderBin");
 558         if ( alt <= layer_asl ) {
 559           layer_root->setSingleChildOn(0);
 560         } else if ( alt >= layer_asl + layer_thickness ) {
 561           layer_root->setSingleChildOn(1);
 562         } else {
 563           layer_root->setAllChildrenOff();
 564         }
 565
 566
 567         // now calculate update texture coordinates
 568         SGGeod pos = SGGeod::fromRad(lon, lat);
 569         if ( last_pos == SGGeod() ) {
 570             last_pos = pos;
 571         }
 572
 573         double sp_dist = speed*dt;
 574
 575
 576         if ( lon != last_pos.getLongitudeRad() || lat != last_pos.getLatitudeRad() || sp_dist != 0 ) {
 577             double course = SGGeodesy::courseDeg(last_pos, pos) * SG_DEGREES_TO_RADIANS,
 578                 dist = SGGeodesy::distanceM(last_pos, pos);
 579
 580             // if start and dest are too close together,
 581             // calc_gc_course_dist() can return a course of "nan".  If
 582             // this happens, lets just use the last known good course.
 583             // This is a hack, and it would probably be better to make
 584             // calc_gc_course_dist() more robust.
 585             if ( isNaN(course) ) {
 586                 course = last_course;
 587             } else {
 588                 last_course = course;
 589             }
 590
 591             // calculate cloud movement due to external forces
 592             double ax = 0.0, ay = 0.0, bx = 0.0, by = 0.0;
 593
 594             if (dist > 0.0) {
 595                 ax = -cos(course) * dist;
 596                 ay = sin(course) * dist;
 597             }
 598
 599             if (sp_dist > 0) {
 600                 bx = cos((180.0-direction) * SGD_DEGREES_TO_RADIANS) * sp_dist;
 601                 by = sin((180.0-direction) * SGD_DEGREES_TO_RADIANS) * sp_dist;
 602             }
 603
 604
 605             double xoff = (ax + bx) / (2 * scale);
 606             double yoff = (ay + by) / (2 * scale);
 607
 608
 609     //        const float layer_scale = layer_span / scale;
 610
 611             // cout << "xoff = " << xoff << ", yoff = " << yoff << endl;
 612             base[0] += xoff;
 613
 614             // the while loops can lead to *long* pauses if base[0] comes
 615             // with a bogus value.
 616             // while ( base[0] > 1.0 ) { base[0] -= 1.0; }
 617             // while ( base[0] < 0.0 ) { base[0] += 1.0; }
 618             if ( base[0] > -10.0 && base[0] < 10.0 ) {
 619                 base[0] -= (int)base[0];
 620             } else {
 621                 SG_LOG(SG_ASTRO, SG_DEBUG,
 622                     "Error: base = " << base[0] << "," << base[1] <<
 623                     " course = " << course << " dist = " << dist );
 624                 base[0] = 0.0;
 625             }
 626
 627             base[1] += yoff;
 628             // the while loops can lead to *long* pauses if base[0] comes
 629             // with a bogus value.
 630             // while ( base[1] > 1.0 ) { base[1] -= 1.0; }
 631             // while ( base[1] < 0.0 ) { base[1] += 1.0; }
 632             if ( base[1] > -10.0 && base[1] < 10.0 ) {
 633                 base[1] -= (int)base[1];
 634             } else {
 635                 SG_LOG(SG_ASTRO, SG_DEBUG,
 636                         "Error: base = " << base[0] << "," << base[1] <<
 637                         " course = " << course << " dist = " << dist );
 638                 base[1] = 0.0;
 639             }
 640
 641             // cout << "base = " << base[0] << "," << base[1] << endl;
 642
 643             setTextureOffset(base);
 644             last_pos = pos;
 645         }
 646     }
 647
 648     layer3D->reposition( p, up, lon, lat, dt, layer_asl, speed, direction);
 649     return true;
 650 }
 651
 652 void SGCloudLayer::set_enable3dClouds(bool enable) {
 653
 654     if (layer3D->isDefined3D() && enable) {
 655         cloud_root->setChildValue(layer3D->getNode(), true);
 656         cloud_root->setChildValue(layer_root.get(),   false);
 657     } else {
 658         cloud_root->setChildValue(layer3D->getNode(), false);
 659         cloud_root->setChildValue(layer_root.get(),   true);
 660     }
 661 }