src/FDM/groundcache.cxx

   1 // groundcache.cxx -- carries a small subset of the scenegraph near the vehicle
   2 //
   3 // Written by Mathias Froehlich, started Nov 2004.
   4 //
   5 // Copyright (C) 2004, 2009  Mathias Froehlich - Mathias.Froehlich@web.de
   6 //
   7 // This program is free software; you can redistribute it and/or
   8 // modify it under the terms of the GNU General Public License as
   9 // published by the Free Software Foundation; either version 2 of the
  10 // License, or (at your option) any later version.
  11 //
  12 // This program 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 // $Id$
  22
  23 #ifdef HAVE_CONFIG_H
  24 #  include "config.h"
  25 #endif
  26
  27 #include <utility>
  28
  29 #include <osg/Drawable>
  30 #include <osg/Geode>
  31 #include <osg/Geometry>
  32 #include <osg/Camera>
  33 #include <osg/Transform>
  34 #include <osg/MatrixTransform>
  35 #include <osg/PositionAttitudeTransform>
  36 #include <osg/CameraView>
  37
  38 #include <simgear/sg_inlines.h>
  39 #include <simgear/constants.h>
  40 #include <simgear/debug/logstream.hxx>
  41 #include <simgear/math/sg_geodesy.hxx>
  42 #include <simgear/scene/util/SGNodeMasks.hxx>
  43 #include <simgear/scene/util/SGSceneUserData.hxx>
  44
  45 #include <simgear/scene/bvh/BVHNode.hxx>
  46 #include <simgear/scene/bvh/BVHGroup.hxx>
  47 #include <simgear/scene/bvh/BVHTransform.hxx>
  48 #include <simgear/scene/bvh/BVHMotionTransform.hxx>
  49 #include <simgear/scene/bvh/BVHLineGeometry.hxx>
  50 #include <simgear/scene/bvh/BVHStaticGeometry.hxx>
  51 #include <simgear/scene/bvh/BVHStaticData.hxx>
  52 #include <simgear/scene/bvh/BVHStaticNode.hxx>
  53 #include <simgear/scene/bvh/BVHStaticTriangle.hxx>
  54 #include <simgear/scene/bvh/BVHStaticBinary.hxx>
  55 #include <simgear/scene/bvh/BVHSubTreeCollector.hxx>
  56 #include <simgear/scene/bvh/BVHLineSegmentVisitor.hxx>
  57 #include <simgear/scene/bvh/BVHNearestPointVisitor.hxx>
  58
  59 #include <Main/globals.hxx>
  60 #include <Scenery/scenery.hxx>
  61 #include <Scenery/tilemgr.hxx>
  62
  63 #include "flight.hxx"
  64 #include "groundcache.hxx"
  65
  66 using namespace simgear;
  67
  68 class FGGroundCache::CacheFill : public osg::NodeVisitor {
  69 public:
  70     CacheFill(const SGVec3d& center, const double& radius,
  71               const double& startTime, const double& endTime) :
  72         osg::NodeVisitor(osg::NodeVisitor::TRAVERSE_ACTIVE_CHILDREN),
  73         _center(center),
  74         _radius(radius),
  75         _startTime(startTime),
  76         _endTime(endTime)
  77     {
  78         setTraversalMask(SG_NODEMASK_TERRAIN_BIT);
  79     }
  80     virtual void apply(osg::Node& node)
  81     {
  82         if (!testBoundingSphere(node.getBound()))
  83             return;
  84
  85         addBoundingVolume(node);
  86     }
  87
  88     virtual void apply(osg::Group& group)
  89     {
  90         if (!testBoundingSphere(group.getBound()))
  91             return;
  92
  93         simgear::BVHSubTreeCollector::NodeList parentNodeList;
  94         mSubTreeCollector.pushNodeList(parentNodeList);
  95
  96         traverse(group);
  97         addBoundingVolume(group);
  98
  99         mSubTreeCollector.popNodeList(parentNodeList);
 100     }
 101
 102     virtual void apply(osg::Transform& transform)
 103     { handleTransform(transform); }
 104     virtual void apply(osg::Camera& camera)
 105     {
 106         if (camera.getRenderOrder() != osg::Camera::NESTED_RENDER)
 107             return;
 108         handleTransform(camera);
 109     }
 110     virtual void apply(osg::CameraView& transform)
 111     { handleTransform(transform); }
 112     virtual void apply(osg::MatrixTransform& transform)
 113     { handleTransform(transform); }
 114     virtual void apply(osg::PositionAttitudeTransform& transform)
 115     { handleTransform(transform); }
 116
 117     void handleTransform(osg::Transform& transform)
 118     {
 119         // Hmm, may be this needs to be refined somehow ...
 120         if (transform.getReferenceFrame() != osg::Transform::RELATIVE_RF)
 121             return;
 122
 123         if (!testBoundingSphere(transform.getBound()))
 124             return;
 125
 126         osg::Matrix inverseMatrix;
 127         if (!transform.computeWorldToLocalMatrix(inverseMatrix, this))
 128             return;
 129         osg::Matrix matrix;
 130         if (!transform.computeLocalToWorldMatrix(matrix, this))
 131             return;
 132
 133         // Look for a velocity note
 134         const SGSceneUserData::Velocity* velocity = getVelocity(transform);
 135
 136         SGVec3d center = _center;
 137         _center = SGVec3d(inverseMatrix.preMult(_center.osg()));
 138         double radius = _radius;
 139         if (velocity)
 140             _radius += (_endTime - _startTime)*norm(velocity->linear);
 141
 142         simgear::BVHSubTreeCollector::NodeList parentNodeList;
 143         mSubTreeCollector.pushNodeList(parentNodeList);
 144
 145         addBoundingVolume(transform);
 146         traverse(transform);
 147
 148         if (mSubTreeCollector.haveChildren()) {
 149             if (velocity) {
 150                 simgear::BVHMotionTransform* bvhTransform;
 151                 bvhTransform = new simgear::BVHMotionTransform;
 152                 bvhTransform->setToWorldTransform(SGMatrixd(matrix.ptr()));
 153                 bvhTransform->setLinearVelocity(velocity->linear);
 154                 bvhTransform->setAngularVelocity(velocity->angular);
 155                 bvhTransform->setReferenceTime(_startTime);
 156                 bvhTransform->setEndTime(_endTime);
 157                 bvhTransform->setId(velocity->id);
 158
 159                 mSubTreeCollector.popNodeList(parentNodeList, bvhTransform);
 160             } else {
 161                 simgear::BVHTransform* bvhTransform;
 162                 bvhTransform = new simgear::BVHTransform;
 163                 bvhTransform->setToWorldTransform(SGMatrixd(matrix.ptr()));
 164
 165                 mSubTreeCollector.popNodeList(parentNodeList, bvhTransform);
 166             }
 167         } else {
 168             mSubTreeCollector.popNodeList(parentNodeList);
 169         }
 170         _center = center;
 171         _radius = radius;
 172     }
 173
 174     const SGSceneUserData::Velocity* getVelocity(osg::Node& node)
 175     {
 176         SGSceneUserData* userData = SGSceneUserData::getSceneUserData(&node);
 177         if (!userData)
 178             return 0;
 179         return userData->getVelocity();
 180     }
 181     simgear::BVHNode* getNodeBoundingVolume(osg::Node& node)
 182     {
 183         SGSceneUserData* userData = SGSceneUserData::getSceneUserData(&node);
 184         if (!userData)
 185             return 0;
 186         return userData->getBVHNode();
 187     }
 188     void addBoundingVolume(osg::Node& node)
 189     {
 190         simgear::BVHNode* bvNode = getNodeBoundingVolume(node);
 191         if (!bvNode)
 192             return;
 193
 194         // Get that part of the local bv tree that intersects our sphere
 195         // of interrest.
 196         mSubTreeCollector.setSphere(SGSphered(_center, _radius));
 197         bvNode->accept(mSubTreeCollector);
 198     }
 199
 200     bool testBoundingSphere(const osg::BoundingSphere& bound) const
 201     {
 202         if (!bound.valid())
 203             return false;
 204
 205         double maxDist = bound._radius + _radius;
 206         return distSqr(SGVec3d(bound._center), _center) <= maxDist*maxDist;
 207     }
 208
 209     SGSharedPtr<simgear::BVHNode> getBVHNode() const
 210     { return mSubTreeCollector.getNode(); }
 211
 212 private:
 213
 214     SGVec3d _center;
 215     double _radius;
 216     double _startTime;
 217     double _endTime;
 218
 219     simgear::BVHSubTreeCollector mSubTreeCollector;
 220 };
 221
 222 FGGroundCache::FGGroundCache() :
 223     _altitude(0),
 224     _material(0),
 225     cache_ref_time(0),
 226     _wire(0),
 227     reference_wgs84_point(SGVec3d(0, 0, 0)),
 228     reference_vehicle_radius(0),
 229     down(0.0, 0.0, 0.0),
 230     found_ground(false)
 231 {
 232 }
 233
 234 FGGroundCache::~FGGroundCache()
 235 {
 236 }
 237
 238 bool
 239 FGGroundCache::prepare_ground_cache(double ref_time, const SGVec3d& pt,
 240                                     double rad)
 241 {
 242     // Empty cache.
 243     found_ground = false;
 244
 245     SGGeod geodPt = SGGeod::fromCart(pt);
 246     // Don't blow away the cache ground_radius and stuff if there's no
 247     // scenery
 248     if (!globals->get_tile_mgr()->scenery_available(geodPt.getLatitudeDeg(),
 249                                                     geodPt.getLongitudeDeg(),
 250                                                     rad))
 251         return false;
 252     _altitude = 0;
 253
 254     // If we have an active wire, get some more area into the groundcache
 255     if (_wire)
 256         rad = SGMiscd::max(200, rad);
 257
 258     // Store the parameters we used to build up that cache.
 259     reference_wgs84_point = pt;
 260     reference_vehicle_radius = rad;
 261     // Store the time reference used to compute movements of moving triangles.
 262     cache_ref_time = ref_time;
 263
 264     // Get a normalized down vector valid for the whole cache
 265     SGQuatd hlToEc = SGQuatd::fromLonLat(geodPt);
 266     down = hlToEc.rotate(SGVec3d(0, 0, 1));
 267
 268     // Get the ground cache, that is a local collision tree of the environment
 269     double endTime = cache_ref_time + 1; //FIXME??
 270     CacheFill subtreeCollector(pt, rad, cache_ref_time, endTime);
 271     globals->get_scenery()->get_scene_graph()->accept(subtreeCollector);
 272     _localBvhTree = subtreeCollector.getBVHNode();
 273
 274     // Try to get a croase altitude value for the ground cache
 275     SGLineSegmentd line(pt, pt + 2*reference_vehicle_radius*down);
 276     simgear::BVHLineSegmentVisitor lineSegmentVisitor(line, ref_time);
 277     if (_localBvhTree)
 278         _localBvhTree->accept(lineSegmentVisitor);
 279
 280     // If this is successful, store this altitude for croase altitude values
 281     if (!lineSegmentVisitor.empty()) {
 282         SGGeod geodPt = SGGeod::fromCart(lineSegmentVisitor.getPoint());
 283         _altitude = geodPt.getElevationM();
 284         _material = lineSegmentVisitor.getMaterial();
 285         found_ground = true;
 286     } else {
 287         // Else do a crude scene query for the current point
 288         found_ground = globals->get_scenery()->
 289             get_cart_elevation_m(pt, rad, _altitude, &_material);
 290     }
 291
 292     // Still not sucessful??
 293     if (!found_ground)
 294         SG_LOG(SG_FLIGHT, SG_WARN, "prepare_ground_cache(): trying to build "
 295                "cache without any scenery below the aircraft");
 296
 297     return found_ground;
 298 }
 299
 300 bool
 301 FGGroundCache::is_valid(double& ref_time, SGVec3d& pt, double& rad)
 302 {
 303     pt = reference_wgs84_point;
 304     rad = reference_vehicle_radius;
 305     ref_time = cache_ref_time;
 306     return found_ground;
 307 }
 308
 309 class FGGroundCache::BodyFinder : public BVHVisitor {
 310 public:
 311     BodyFinder(BVHNode::Id id, const double& t) :
 312         _id(id),
 313         _bodyToWorld(SGMatrixd::unit()),
 314         _linearVelocity(0, 0, 0),
 315         _angularVelocity(0, 0, 0),
 316         _time(t)
 317     { }
 318
 319     virtual void apply(BVHGroup& leaf)
 320     {
 321         if (_foundId)
 322             return;
 323         leaf.traverse(*this);
 324     }
 325     virtual void apply(BVHTransform& transform)
 326     {
 327         if (_foundId)
 328             return;
 329
 330         transform.traverse(*this);
 331
 332         if (_foundId) {
 333             _linearVelocity = transform.vecToWorld(_linearVelocity);
 334             _angularVelocity = transform.vecToWorld(_angularVelocity);
 335             _bodyToWorld = transform.getToWorldTransform()*_bodyToWorld;
 336         }
 337     }
 338     virtual void apply(BVHMotionTransform& transform)
 339     {
 340         if (_foundId)
 341             return;
 342
 343         if (_id == transform.getId()) {
 344             _foundId = true;
 345             return;
 346         }
 347
 348         transform.traverse(*this);
 349
 350         if (_foundId) {
 351             SGMatrixd toWorld = transform.getToWorldTransform(_time);
 352             SGVec3d referencePoint = _bodyToWorld.xformPt(SGVec3d::zeros());
 353             _linearVelocity += transform.getLinearVelocityAt(referencePoint);
 354             _angularVelocity += transform.getAngularVelocity();
 355             _linearVelocity = toWorld.xformVec(_linearVelocity);
 356             _angularVelocity = toWorld.xformVec(_angularVelocity);
 357             _bodyToWorld = toWorld*_bodyToWorld;
 358         }
 359     }
 360     virtual void apply(BVHLineGeometry& node) { }
 361     virtual void apply(BVHStaticGeometry& node) { }
 362
 363     virtual void apply(const BVHStaticBinary&, const BVHStaticData&) { }
 364     virtual void apply(const BVHStaticTriangle&, const BVHStaticData&) { }
 365
 366     const SGMatrixd& getBodyToWorld() const
 367     { return _bodyToWorld; }
 368     const SGVec3d& getLinearVelocity() const
 369     { return _linearVelocity; }
 370     const SGVec3d& getAngularVelocity() const
 371     { return _angularVelocity; }
 372
 373     bool empty() const
 374     { return !_foundId; }
 375
 376 protected:
 377     simgear::BVHNode::Id _id;
 378
 379     SGMatrixd _bodyToWorld;
 380
 381     SGVec3d _linearVelocity;
 382     SGVec3d _angularVelocity;
 383
 384     bool _foundId;
 385
 386     double _time;
 387 };
 388
 389 bool
 390 FGGroundCache::get_body(double t, SGMatrixd& bodyToWorld, SGVec3d& linearVel,
 391                         SGVec3d& angularVel, simgear::BVHNode::Id id)
 392 {
 393     // Get the transform matrix and velocities of a moving body with id at t.
 394     if (!_localBvhTree)
 395         return false;
 396     BodyFinder bodyFinder(id, t);
 397     _localBvhTree->accept(bodyFinder);
 398     if (bodyFinder.empty())
 399         return false;
 400
 401     bodyToWorld = bodyFinder.getBodyToWorld();
 402     linearVel = bodyFinder.getLinearVelocity();
 403     angularVel = bodyFinder.getAngularVelocity();
 404
 405     return true;
 406 }
 407
 408 class FGGroundCache::CatapultFinder : public BVHVisitor {
 409 public:
 410     CatapultFinder(const SGSphered& sphere, const double& t) :
 411         _sphere(sphere),
 412         _time(t),
 413         _haveLineSegment(false)
 414     { }
 415
 416     virtual void apply(BVHGroup& leaf)
 417     {
 418         if (!intersects(_sphere, leaf.getBoundingSphere()))
 419             return;
 420         leaf.traverse(*this);
 421     }
 422     virtual void apply(BVHTransform& transform)
 423     {
 424         if (!intersects(_sphere, transform.getBoundingSphere()))
 425             return;
 426
 427         SGSphered sphere = _sphere;
 428         _sphere = transform.sphereToLocal(sphere);
 429         bool haveLineSegment = _haveLineSegment;
 430         _haveLineSegment = false;
 431
 432         transform.traverse(*this);
 433
 434         if (_haveLineSegment) {
 435             _lineSegment = transform.lineSegmentToWorld(_lineSegment);
 436             _linearVelocity = transform.vecToWorld(_linearVelocity);
 437             _angularVelocity = transform.vecToWorld(_angularVelocity);
 438         }
 439         _haveLineSegment |= haveLineSegment;
 440         _sphere.setCenter(sphere.getCenter());
 441     }
 442     virtual void apply(BVHMotionTransform& transform)
 443     {
 444         if (!intersects(_sphere, transform.getBoundingSphere()))
 445             return;
 446
 447         SGSphered sphere = _sphere;
 448         _sphere = transform.sphereToLocal(sphere, _time);
 449         bool haveLineSegment = _haveLineSegment;
 450         _haveLineSegment = false;
 451
 452         transform.traverse(*this);
 453
 454         if (_haveLineSegment) {
 455             SGMatrixd toWorld = transform.getToWorldTransform(_time);
 456             _linearVelocity
 457                 += transform.getLinearVelocityAt(_lineSegment.getStart());
 458             _angularVelocity += transform.getAngularVelocity();
 459             _linearVelocity = toWorld.xformVec(_linearVelocity);
 460             _angularVelocity = toWorld.xformVec(_angularVelocity);
 461             _lineSegment = _lineSegment.transform(toWorld);
 462         }
 463         _haveLineSegment |= haveLineSegment;
 464         _sphere.setCenter(sphere.getCenter());
 465     }
 466     virtual void apply(BVHLineGeometry& node)
 467     {
 468         if (node.getType() != BVHLineGeometry::CarrierCatapult)
 469             return;
 470
 471         SGLineSegmentd lineSegment(node.getLineSegment());
 472         if (!intersects(_sphere, lineSegment))
 473             return;
 474
 475         _lineSegment = lineSegment;
 476         double dist = distSqr(lineSegment, getSphere().getCenter());
 477         _sphere.setRadius(sqrt(dist));
 478         _linearVelocity = SGVec3d::zeros();
 479         _angularVelocity = SGVec3d::zeros();
 480         _haveLineSegment = true;
 481     }
 482     virtual void apply(BVHStaticGeometry& node)
 483     { }
 484
 485     virtual void apply(const BVHStaticBinary&, const BVHStaticData&) { }
 486     virtual void apply(const BVHStaticTriangle&, const BVHStaticData&) { }
 487
 488     void setSphere(const SGSphered& sphere)
 489     { _sphere = sphere; }
 490     const SGSphered& getSphere() const
 491     { return _sphere; }
 492
 493     const SGLineSegmentd& getLineSegment() const
 494     { return _lineSegment; }
 495     const SGVec3d& getLinearVelocity() const
 496     { return _linearVelocity; }
 497     const SGVec3d& getAngularVelocity() const
 498     { return _angularVelocity; }
 499
 500     bool getHaveLineSegment() const
 501     { return _haveLineSegment; }
 502
 503 protected:
 504     SGLineSegmentd _lineSegment;
 505     SGVec3d _linearVelocity;
 506     SGVec3d _angularVelocity;
 507
 508     bool _haveLineSegment;
 509
 510     SGSphered _sphere;
 511     double _time;
 512 };
 513
 514 double
 515 FGGroundCache::get_cat(double t, const SGVec3d& pt,
 516                        SGVec3d end[2], SGVec3d vel[2])
 517 {
 518     double maxDistance = 1000;
 519
 520     // Get the wire in question
 521     CatapultFinder catapultFinder(SGSphered(pt, maxDistance), t);
 522     if (_localBvhTree)
 523         _localBvhTree->accept(catapultFinder);
 524
 525     if (!catapultFinder.getHaveLineSegment())
 526         return maxDistance;
 527
 528     // prepare the returns
 529     end[0] = catapultFinder.getLineSegment().getStart();
 530     end[1] = catapultFinder.getLineSegment().getEnd();
 531
 532     // The linear velocity is the one at the start of the line segment ...
 533     vel[0] = catapultFinder.getLinearVelocity();
 534     // ... so the end point has the additional cross product.
 535     vel[1] = catapultFinder.getLinearVelocity();
 536     vel[1] += cross(catapultFinder.getAngularVelocity(),
 537                     catapultFinder.getLineSegment().getDirection());
 538
 539     // Return the distance to the cat
 540     return sqrt(distSqr(catapultFinder.getLineSegment(), pt));
 541 }
 542
 543 bool
 544 FGGroundCache::get_agl(double t, const SGVec3d& pt, SGVec3d& contact,
 545                        SGVec3d& normal, SGVec3d& linearVel, SGVec3d& angularVel,
 546                        simgear::BVHNode::Id& id, const SGMaterial*& material)
 547 {
 548     // Just set up a ground intersection query for the given point
 549     SGLineSegmentd line(pt, pt + 10*reference_vehicle_radius*down);
 550     simgear::BVHLineSegmentVisitor lineSegmentVisitor(line, t);
 551     if (_localBvhTree)
 552         _localBvhTree->accept(lineSegmentVisitor);
 553
 554     if (!lineSegmentVisitor.empty()) {
 555         // Have an intersection
 556         contact = lineSegmentVisitor.getPoint();
 557         normal = lineSegmentVisitor.getNormal();
 558         if (0 < dot(normal, down))
 559             normal = -normal;
 560         linearVel = lineSegmentVisitor.getLinearVelocity();
 561         angularVel = lineSegmentVisitor.getAngularVelocity();
 562         material = lineSegmentVisitor.getMaterial();
 563         id = lineSegmentVisitor.getId();
 564
 565         return true;
 566     } else {
 567         // Whenever we did not have a ground triangle for the requested point,
 568         // take the ground level we found during the current cache build.
 569         // This is as good as what we had before for agl.
 570         SGGeod geodPt = SGGeod::fromCart(pt);
 571         geodPt.setElevationM(_altitude);
 572         contact = SGVec3d::fromGeod(geodPt);
 573         normal = -down;
 574         linearVel = SGVec3d(0, 0, 0);
 575         angularVel = SGVec3d(0, 0, 0);
 576         material = _material;
 577         id = 0;
 578
 579         return found_ground;
 580     }
 581 }
 582
 583
 584 bool
 585 FGGroundCache::get_nearest(double t, const SGVec3d& pt, double maxDist,
 586                            SGVec3d& contact, SGVec3d& linearVel,
 587                            SGVec3d& angularVel, simgear::BVHNode::Id& id,
 588                            const SGMaterial*& material)
 589 {
 590     if (!_localBvhTree)
 591         return false;
 592
 593     // Just set up a ground intersection query for the given point
 594     SGSphered sphere(pt, maxDist);
 595     simgear::BVHNearestPointVisitor nearestPointVisitor(sphere, t);
 596     _localBvhTree->accept(nearestPointVisitor);
 597
 598     if (nearestPointVisitor.empty())
 599         return false;
 600
 601     // Have geometry in the range of maxDist
 602     contact = nearestPointVisitor.getPoint();
 603     linearVel = nearestPointVisitor.getLinearVelocity();
 604     angularVel = nearestPointVisitor.getAngularVelocity();
 605     material = nearestPointVisitor.getMaterial();
 606     id = nearestPointVisitor.getId();
 607
 608     return true;
 609 }
 610
 611
 612 class FGGroundCache::WireIntersector : public BVHVisitor {
 613 public:
 614     WireIntersector(const SGVec3d pt[4], const double& t) :
 615         _linearVelocity(SGVec3d::zeros()),
 616         _angularVelocity(SGVec3d::zeros()),
 617         _wire(0),
 618         _time(t)
 619     {
 620         // Build the two triangles spanning the area where the hook has moved
 621         // during the past step.
 622         _triangles[0].set(pt[0], pt[1], pt[2]);
 623         _triangles[1].set(pt[0], pt[2], pt[3]);
 624     }
 625
 626     virtual void apply(BVHGroup& leaf)
 627     {
 628         if (!_intersects(leaf.getBoundingSphere()))
 629             return;
 630
 631         leaf.traverse(*this);
 632     }
 633     virtual void apply(BVHTransform& transform)
 634     {
 635         if (!_intersects(transform.getBoundingSphere()))
 636             return;
 637
 638         SGTriangled triangles[2] = { _triangles[0], _triangles[1] };
 639         _triangles[0] = triangles[0].transform(transform.getToLocalTransform());
 640         _triangles[1] = triangles[1].transform(transform.getToLocalTransform());
 641
 642         transform.traverse(*this);
 643
 644         if (_wire) {
 645             _lineSegment = transform.lineSegmentToWorld(_lineSegment);
 646             _linearVelocity = transform.vecToWorld(_linearVelocity);
 647             _angularVelocity = transform.vecToWorld(_angularVelocity);
 648         }
 649         _triangles[0] = triangles[0];
 650         _triangles[1] = triangles[1];
 651     }
 652     virtual void apply(BVHMotionTransform& transform)
 653     {
 654         if (!_intersects(transform.getBoundingSphere()))
 655             return;
 656
 657         SGMatrixd toLocal = transform.getToLocalTransform(_time);
 658
 659         SGTriangled triangles[2] = { _triangles[0], _triangles[1] };
 660         _triangles[0] = triangles[0].transform(toLocal);
 661         _triangles[1] = triangles[1].transform(toLocal);
 662
 663         transform.traverse(*this);
 664
 665         if (_wire) {
 666             SGMatrixd toWorld = transform.getToWorldTransform(_time);
 667             _linearVelocity
 668                 += transform.getLinearVelocityAt(_lineSegment.getStart());
 669             _angularVelocity += transform.getAngularVelocity();
 670             _linearVelocity = toWorld.xformVec(_linearVelocity);
 671             _angularVelocity = toWorld.xformVec(_angularVelocity);
 672             _lineSegment = _lineSegment.transform(toWorld);
 673         }
 674         _triangles[0] = triangles[0];
 675         _triangles[1] = triangles[1];
 676     }
 677     virtual void apply(BVHLineGeometry& node)
 678     {
 679         if (node.getType() != BVHLineGeometry::CarrierWire)
 680             return;
 681         SGLineSegmentd lineSegment(node.getLineSegment());
 682         if (!_intersects(lineSegment))
 683             return;
 684
 685         _lineSegment = lineSegment;
 686         _linearVelocity = SGVec3d::zeros();
 687         _angularVelocity = SGVec3d::zeros();
 688         _wire = &node;
 689     }
 690     virtual void apply(BVHStaticGeometry& node)
 691     { }
 692
 693     virtual void apply(const BVHStaticBinary&, const BVHStaticData&) { }
 694     virtual void apply(const BVHStaticTriangle&, const BVHStaticData&) { }
 695
 696     bool _intersects(const SGSphered& sphere) const
 697     {
 698         if (_wire)
 699             return false;
 700         if (intersects(_triangles[0], sphere))
 701             return true;
 702         if (intersects(_triangles[1], sphere))
 703             return true;
 704         return false;
 705     }
 706     bool _intersects(const SGLineSegmentd& lineSegment) const
 707     {
 708         if (_wire)
 709             return false;
 710         if (intersects(_triangles[0], lineSegment))
 711             return true;
 712         if (intersects(_triangles[1], lineSegment))
 713             return true;
 714         return false;
 715     }
 716
 717     const SGLineSegmentd& getLineSegment() const
 718     { return _lineSegment; }
 719     const SGVec3d& getLinearVelocity() const
 720     { return _linearVelocity; }
 721     const SGVec3d& getAngularVelocity() const
 722     { return _angularVelocity; }
 723
 724     const BVHLineGeometry* getWire() const
 725     { return _wire; }
 726
 727 private:
 728     SGLineSegmentd _lineSegment;
 729     SGVec3d _linearVelocity;
 730     SGVec3d _angularVelocity;
 731     const BVHLineGeometry* _wire;
 732
 733     SGTriangled _triangles[2];
 734     double _time;
 735 };
 736
 737 bool FGGroundCache::caught_wire(double t, const SGVec3d pt[4])
 738 {
 739     // Get the wire in question
 740     WireIntersector wireIntersector(pt, t);
 741     if (_localBvhTree)
 742         _localBvhTree->accept(wireIntersector);
 743
 744     _wire = wireIntersector.getWire();
 745     return _wire;
 746 }
 747
 748 class FGGroundCache::WireFinder : public BVHVisitor {
 749 public:
 750     WireFinder(const BVHLineGeometry* wire, const double& t) :
 751         _wire(wire),
 752         _time(t),
 753         _lineSegment(SGVec3d::zeros(), SGVec3d::zeros()),
 754         _linearVelocity(SGVec3d::zeros()),
 755         _angularVelocity(SGVec3d::zeros()),
 756         _haveLineSegment(false)
 757     { }
 758
 759     virtual void apply(BVHGroup& leaf)
 760     {
 761         if (_haveLineSegment)
 762             return;
 763         leaf.traverse(*this);
 764     }
 765     virtual void apply(BVHTransform& transform)
 766     {
 767         if (_haveLineSegment)
 768             return;
 769
 770         transform.traverse(*this);
 771
 772         if (_haveLineSegment) {
 773             _linearVelocity = transform.vecToWorld(_linearVelocity);
 774             _angularVelocity = transform.vecToWorld(_angularVelocity);
 775             _lineSegment = transform.lineSegmentToWorld(_lineSegment);
 776         }
 777     }
 778     virtual void apply(BVHMotionTransform& transform)
 779     {
 780         if (_haveLineSegment)
 781             return;
 782
 783         transform.traverse(*this);
 784
 785         if (_haveLineSegment) {
 786             SGMatrixd toWorld = transform.getToWorldTransform(_time);
 787             _linearVelocity
 788                 += transform.getLinearVelocityAt(_lineSegment.getStart());
 789             _angularVelocity += transform.getAngularVelocity();
 790             _linearVelocity = toWorld.xformVec(_linearVelocity);
 791             _angularVelocity = toWorld.xformVec(_angularVelocity);
 792             _lineSegment = _lineSegment.transform(toWorld);
 793         }
 794     }
 795     virtual void apply(BVHLineGeometry& node)
 796     {
 797         if (_haveLineSegment)
 798             return;
 799         if (_wire != &node)
 800             return;
 801         if (node.getType() != BVHLineGeometry::CarrierWire)
 802             return;
 803         _lineSegment = SGLineSegmentd(node.getLineSegment());
 804         _linearVelocity = SGVec3d::zeros();
 805         _angularVelocity = SGVec3d::zeros();
 806         _haveLineSegment = true;
 807     }
 808     virtual void apply(BVHStaticGeometry&) { }
 809
 810     virtual void apply(const BVHStaticBinary&, const BVHStaticData&) { }
 811     virtual void apply(const BVHStaticTriangle&, const BVHStaticData&) { }
 812
 813     const SGLineSegmentd& getLineSegment() const
 814     { return _lineSegment; }
 815
 816     bool getHaveLineSegment() const
 817     { return _haveLineSegment; }
 818
 819     const SGVec3d& getLinearVelocity() const
 820     { return _linearVelocity; }
 821     const SGVec3d& getAngularVelocity() const
 822     { return _angularVelocity; }
 823
 824 private:
 825     const BVHLineGeometry* _wire;
 826     double _time;
 827
 828     SGLineSegmentd _lineSegment;
 829     SGVec3d _linearVelocity;
 830     SGVec3d _angularVelocity;
 831
 832     bool _haveLineSegment;
 833 };
 834
 835 bool FGGroundCache::get_wire_ends(double t, SGVec3d end[2], SGVec3d vel[2])
 836 {
 837     // Fast return if we do not have an active wire.
 838     if (!_wire)
 839         return false;
 840
 841     // Get the wire in question
 842     WireFinder wireFinder(_wire, t);
 843     if (_localBvhTree)
 844         _localBvhTree->accept(wireFinder);
 845
 846     if (!wireFinder.getHaveLineSegment())
 847         return false;
 848
 849     // prepare the returns
 850     end[0] = wireFinder.getLineSegment().getStart();
 851     end[1] = wireFinder.getLineSegment().getEnd();
 852
 853     // The linear velocity is the one at the start of the line segment ...
 854     vel[0] = wireFinder.getLinearVelocity();
 855     // ... so the end point has the additional cross product.
 856     vel[1] = wireFinder.getLinearVelocity();
 857     vel[1] += cross(wireFinder.getAngularVelocity(),
 858                     wireFinder.getLineSegment().getDirection());
 859
 860     return true;
 861 }
 862
 863 void FGGroundCache::release_wire(void)
 864 {
 865     _wire = 0;
 866 }