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, rad))
 249         return false;
 250     _altitude = 0;
 251
 252     // If we have an active wire, get some more area into the groundcache
 253     if (_wire)
 254         rad = SGMiscd::max(200, rad);
 255
 256     // Store the parameters we used to build up that cache.
 257     reference_wgs84_point = pt;
 258     reference_vehicle_radius = rad;
 259     // Store the time reference used to compute movements of moving triangles.
 260     cache_ref_time = ref_time;
 261
 262     // Get a normalized down vector valid for the whole cache
 263     SGQuatd hlToEc = SGQuatd::fromLonLat(geodPt);
 264     down = hlToEc.rotate(SGVec3d(0, 0, 1));
 265
 266     // Get the ground cache, that is a local collision tree of the environment
 267     double endTime = cache_ref_time + 1; //FIXME??
 268     CacheFill subtreeCollector(pt, rad, cache_ref_time, endTime);
 269     globals->get_scenery()->get_scene_graph()->accept(subtreeCollector);
 270     _localBvhTree = subtreeCollector.getBVHNode();
 271
 272     // Try to get a croase altitude value for the ground cache
 273     SGLineSegmentd line(pt, pt + 2*reference_vehicle_radius*down);
 274     simgear::BVHLineSegmentVisitor lineSegmentVisitor(line, ref_time);
 275     if (_localBvhTree)
 276         _localBvhTree->accept(lineSegmentVisitor);
 277
 278     // If this is successful, store this altitude for croase altitude values
 279     if (!lineSegmentVisitor.empty()) {
 280         SGGeod geodPt = SGGeod::fromCart(lineSegmentVisitor.getPoint());
 281         _altitude = geodPt.getElevationM();
 282         _material = lineSegmentVisitor.getMaterial();
 283         found_ground = true;
 284     } else {
 285         // Else do a crude scene query for the current point
 286         found_ground = globals->get_scenery()->
 287             get_cart_elevation_m(pt, rad, _altitude, &_material);
 288     }
 289
 290     // Still not sucessful??
 291     if (!found_ground)
 292         SG_LOG(SG_FLIGHT, SG_WARN, "prepare_ground_cache(): trying to build "
 293                "cache without any scenery below the aircraft");
 294
 295     return found_ground;
 296 }
 297
 298 bool
 299 FGGroundCache::is_valid(double& ref_time, SGVec3d& pt, double& rad)
 300 {
 301     pt = reference_wgs84_point;
 302     rad = reference_vehicle_radius;
 303     ref_time = cache_ref_time;
 304     return found_ground;
 305 }
 306
 307 class FGGroundCache::BodyFinder : public BVHVisitor {
 308 public:
 309     BodyFinder(BVHNode::Id id, const double& t) :
 310         _id(id),
 311         _bodyToWorld(SGMatrixd::unit()),
 312         _linearVelocity(0, 0, 0),
 313         _angularVelocity(0, 0, 0),
 314         _time(t)
 315     { }
 316
 317     virtual void apply(BVHGroup& leaf)
 318     {
 319         if (_foundId)
 320             return;
 321         leaf.traverse(*this);
 322     }
 323     virtual void apply(BVHTransform& transform)
 324     {
 325         if (_foundId)
 326             return;
 327
 328         transform.traverse(*this);
 329
 330         if (_foundId) {
 331             _linearVelocity = transform.vecToWorld(_linearVelocity);
 332             _angularVelocity = transform.vecToWorld(_angularVelocity);
 333             _bodyToWorld = transform.getToWorldTransform()*_bodyToWorld;
 334         }
 335     }
 336     virtual void apply(BVHMotionTransform& transform)
 337     {
 338         if (_foundId)
 339             return;
 340
 341         if (_id == transform.getId()) {
 342             _foundId = true;
 343             return;
 344         }
 345
 346         transform.traverse(*this);
 347
 348         if (_foundId) {
 349             SGMatrixd toWorld = transform.getToWorldTransform(_time);
 350             SGVec3d referencePoint = _bodyToWorld.xformPt(SGVec3d::zeros());
 351             _linearVelocity += transform.getLinearVelocityAt(referencePoint);
 352             _angularVelocity += transform.getAngularVelocity();
 353             _linearVelocity = toWorld.xformVec(_linearVelocity);
 354             _angularVelocity = toWorld.xformVec(_angularVelocity);
 355             _bodyToWorld = toWorld*_bodyToWorld;
 356         }
 357     }
 358     virtual void apply(BVHLineGeometry& node) { }
 359     virtual void apply(BVHStaticGeometry& node) { }
 360
 361     virtual void apply(const BVHStaticBinary&, const BVHStaticData&) { }
 362     virtual void apply(const BVHStaticTriangle&, const BVHStaticData&) { }
 363
 364     const SGMatrixd& getBodyToWorld() const
 365     { return _bodyToWorld; }
 366     const SGVec3d& getLinearVelocity() const
 367     { return _linearVelocity; }
 368     const SGVec3d& getAngularVelocity() const
 369     { return _angularVelocity; }
 370
 371     bool empty() const
 372     { return !_foundId; }
 373
 374 protected:
 375     simgear::BVHNode::Id _id;
 376
 377     SGMatrixd _bodyToWorld;
 378
 379     SGVec3d _linearVelocity;
 380     SGVec3d _angularVelocity;
 381
 382     bool _foundId;
 383
 384     double _time;
 385 };
 386
 387 bool
 388 FGGroundCache::get_body(double t, SGMatrixd& bodyToWorld, SGVec3d& linearVel,
 389                         SGVec3d& angularVel, simgear::BVHNode::Id id)
 390 {
 391     // Get the transform matrix and velocities of a moving body with id at t.
 392     if (!_localBvhTree)
 393         return false;
 394     BodyFinder bodyFinder(id, t);
 395     _localBvhTree->accept(bodyFinder);
 396     if (bodyFinder.empty())
 397         return false;
 398
 399     bodyToWorld = bodyFinder.getBodyToWorld();
 400     linearVel = bodyFinder.getLinearVelocity();
 401     angularVel = bodyFinder.getAngularVelocity();
 402
 403     return true;
 404 }
 405
 406 class FGGroundCache::CatapultFinder : public BVHVisitor {
 407 public:
 408     CatapultFinder(const SGSphered& sphere, const double& t) :
 409         _sphere(sphere),
 410         _time(t),
 411         _haveLineSegment(false)
 412     { }
 413
 414     virtual void apply(BVHGroup& leaf)
 415     {
 416         if (!intersects(_sphere, leaf.getBoundingSphere()))
 417             return;
 418         leaf.traverse(*this);
 419     }
 420     virtual void apply(BVHTransform& transform)
 421     {
 422         if (!intersects(_sphere, transform.getBoundingSphere()))
 423             return;
 424
 425         SGSphered sphere = _sphere;
 426         _sphere = transform.sphereToLocal(sphere);
 427         bool haveLineSegment = _haveLineSegment;
 428         _haveLineSegment = false;
 429
 430         transform.traverse(*this);
 431
 432         if (_haveLineSegment) {
 433             _lineSegment = transform.lineSegmentToWorld(_lineSegment);
 434             _linearVelocity = transform.vecToWorld(_linearVelocity);
 435             _angularVelocity = transform.vecToWorld(_angularVelocity);
 436         }
 437         _haveLineSegment |= haveLineSegment;
 438         _sphere.setCenter(sphere.getCenter());
 439     }
 440     virtual void apply(BVHMotionTransform& transform)
 441     {
 442         if (!intersects(_sphere, transform.getBoundingSphere()))
 443             return;
 444
 445         SGSphered sphere = _sphere;
 446         _sphere = transform.sphereToLocal(sphere, _time);
 447         bool haveLineSegment = _haveLineSegment;
 448         _haveLineSegment = false;
 449
 450         transform.traverse(*this);
 451
 452         if (_haveLineSegment) {
 453             SGMatrixd toWorld = transform.getToWorldTransform(_time);
 454             _linearVelocity
 455                 += transform.getLinearVelocityAt(_lineSegment.getStart());
 456             _angularVelocity += transform.getAngularVelocity();
 457             _linearVelocity = toWorld.xformVec(_linearVelocity);
 458             _angularVelocity = toWorld.xformVec(_angularVelocity);
 459             _lineSegment = _lineSegment.transform(toWorld);
 460         }
 461         _haveLineSegment |= haveLineSegment;
 462         _sphere.setCenter(sphere.getCenter());
 463     }
 464     virtual void apply(BVHLineGeometry& node)
 465     {
 466         if (node.getType() != BVHLineGeometry::CarrierCatapult)
 467             return;
 468
 469         SGLineSegmentd lineSegment(node.getLineSegment());
 470         if (!intersects(_sphere, lineSegment))
 471             return;
 472
 473         _lineSegment = lineSegment;
 474         double dist = distSqr(lineSegment, getSphere().getCenter());
 475         _sphere.setRadius(sqrt(dist));
 476         _linearVelocity = SGVec3d::zeros();
 477         _angularVelocity = SGVec3d::zeros();
 478         _haveLineSegment = true;
 479     }
 480     virtual void apply(BVHStaticGeometry& node)
 481     { }
 482
 483     virtual void apply(const BVHStaticBinary&, const BVHStaticData&) { }
 484     virtual void apply(const BVHStaticTriangle&, const BVHStaticData&) { }
 485
 486     void setSphere(const SGSphered& sphere)
 487     { _sphere = sphere; }
 488     const SGSphered& getSphere() const
 489     { return _sphere; }
 490
 491     const SGLineSegmentd& getLineSegment() const
 492     { return _lineSegment; }
 493     const SGVec3d& getLinearVelocity() const
 494     { return _linearVelocity; }
 495     const SGVec3d& getAngularVelocity() const
 496     { return _angularVelocity; }
 497
 498     bool getHaveLineSegment() const
 499     { return _haveLineSegment; }
 500
 501 protected:
 502     SGLineSegmentd _lineSegment;
 503     SGVec3d _linearVelocity;
 504     SGVec3d _angularVelocity;
 505
 506     bool _haveLineSegment;
 507
 508     SGSphered _sphere;
 509     double _time;
 510 };
 511
 512 double
 513 FGGroundCache::get_cat(double t, const SGVec3d& pt,
 514                        SGVec3d end[2], SGVec3d vel[2])
 515 {
 516     double maxDistance = 1000;
 517
 518     // Get the wire in question
 519     CatapultFinder catapultFinder(SGSphered(pt, maxDistance), t);
 520     if (_localBvhTree)
 521         _localBvhTree->accept(catapultFinder);
 522
 523     if (!catapultFinder.getHaveLineSegment())
 524         return maxDistance;
 525
 526     // prepare the returns
 527     end[0] = catapultFinder.getLineSegment().getStart();
 528     end[1] = catapultFinder.getLineSegment().getEnd();
 529
 530     // The linear velocity is the one at the start of the line segment ...
 531     vel[0] = catapultFinder.getLinearVelocity();
 532     // ... so the end point has the additional cross product.
 533     vel[1] = catapultFinder.getLinearVelocity();
 534     vel[1] += cross(catapultFinder.getAngularVelocity(),
 535                     catapultFinder.getLineSegment().getDirection());
 536
 537     // Return the distance to the cat
 538     return sqrt(distSqr(catapultFinder.getLineSegment(), pt));
 539 }
 540
 541 bool
 542 FGGroundCache::get_agl(double t, const SGVec3d& pt, SGVec3d& contact,
 543                        SGVec3d& normal, SGVec3d& linearVel, SGVec3d& angularVel,
 544                        simgear::BVHNode::Id& id, const SGMaterial*& material)
 545 {
 546     // Just set up a ground intersection query for the given point
 547     SGLineSegmentd line(pt, pt + 10*reference_vehicle_radius*down);
 548     simgear::BVHLineSegmentVisitor lineSegmentVisitor(line, t);
 549     if (_localBvhTree)
 550         _localBvhTree->accept(lineSegmentVisitor);
 551
 552     if (!lineSegmentVisitor.empty()) {
 553         // Have an intersection
 554         contact = lineSegmentVisitor.getPoint();
 555         normal = lineSegmentVisitor.getNormal();
 556         if (0 < dot(normal, down))
 557             normal = -normal;
 558         linearVel = lineSegmentVisitor.getLinearVelocity();
 559         angularVel = lineSegmentVisitor.getAngularVelocity();
 560         material = lineSegmentVisitor.getMaterial();
 561         id = lineSegmentVisitor.getId();
 562
 563         return true;
 564     } else {
 565         // Whenever we did not have a ground triangle for the requested point,
 566         // take the ground level we found during the current cache build.
 567         // This is as good as what we had before for agl.
 568         SGGeod geodPt = SGGeod::fromCart(pt);
 569         geodPt.setElevationM(_altitude);
 570         contact = SGVec3d::fromGeod(geodPt);
 571         normal = -down;
 572         linearVel = SGVec3d(0, 0, 0);
 573         angularVel = SGVec3d(0, 0, 0);
 574         material = _material;
 575         id = 0;
 576
 577         return found_ground;
 578     }
 579 }
 580
 581
 582 bool
 583 FGGroundCache::get_nearest(double t, const SGVec3d& pt, double maxDist,
 584                            SGVec3d& contact, SGVec3d& linearVel,
 585                            SGVec3d& angularVel, simgear::BVHNode::Id& id,
 586                            const SGMaterial*& material)
 587 {
 588     if (!_localBvhTree)
 589         return false;
 590
 591     // Just set up a ground intersection query for the given point
 592     SGSphered sphere(pt, maxDist);
 593     simgear::BVHNearestPointVisitor nearestPointVisitor(sphere, t);
 594     _localBvhTree->accept(nearestPointVisitor);
 595
 596     if (nearestPointVisitor.empty())
 597         return false;
 598
 599     // Have geometry in the range of maxDist
 600     contact = nearestPointVisitor.getPoint();
 601     linearVel = nearestPointVisitor.getLinearVelocity();
 602     angularVel = nearestPointVisitor.getAngularVelocity();
 603     material = nearestPointVisitor.getMaterial();
 604     id = nearestPointVisitor.getId();
 605
 606     return true;
 607 }
 608
 609
 610 class FGGroundCache::WireIntersector : public BVHVisitor {
 611 public:
 612     WireIntersector(const SGVec3d pt[4], const double& t) :
 613         _linearVelocity(SGVec3d::zeros()),
 614         _angularVelocity(SGVec3d::zeros()),
 615         _wire(0),
 616         _time(t)
 617     {
 618         // Build the two triangles spanning the area where the hook has moved
 619         // during the past step.
 620         _triangles[0].set(pt[0], pt[1], pt[2]);
 621         _triangles[1].set(pt[0], pt[2], pt[3]);
 622     }
 623
 624     virtual void apply(BVHGroup& leaf)
 625     {
 626         if (!_intersects(leaf.getBoundingSphere()))
 627             return;
 628
 629         leaf.traverse(*this);
 630     }
 631     virtual void apply(BVHTransform& transform)
 632     {
 633         if (!_intersects(transform.getBoundingSphere()))
 634             return;
 635
 636         SGTriangled triangles[2] = { _triangles[0], _triangles[1] };
 637         _triangles[0] = triangles[0].transform(transform.getToLocalTransform());
 638         _triangles[1] = triangles[1].transform(transform.getToLocalTransform());
 639
 640         transform.traverse(*this);
 641
 642         if (_wire) {
 643             _lineSegment = transform.lineSegmentToWorld(_lineSegment);
 644             _linearVelocity = transform.vecToWorld(_linearVelocity);
 645             _angularVelocity = transform.vecToWorld(_angularVelocity);
 646         }
 647         _triangles[0] = triangles[0];
 648         _triangles[1] = triangles[1];
 649     }
 650     virtual void apply(BVHMotionTransform& transform)
 651     {
 652         if (!_intersects(transform.getBoundingSphere()))
 653             return;
 654
 655         SGMatrixd toLocal = transform.getToLocalTransform(_time);
 656
 657         SGTriangled triangles[2] = { _triangles[0], _triangles[1] };
 658         _triangles[0] = triangles[0].transform(toLocal);
 659         _triangles[1] = triangles[1].transform(toLocal);
 660
 661         transform.traverse(*this);
 662
 663         if (_wire) {
 664             SGMatrixd toWorld = transform.getToWorldTransform(_time);
 665             _linearVelocity
 666                 += transform.getLinearVelocityAt(_lineSegment.getStart());
 667             _angularVelocity += transform.getAngularVelocity();
 668             _linearVelocity = toWorld.xformVec(_linearVelocity);
 669             _angularVelocity = toWorld.xformVec(_angularVelocity);
 670             _lineSegment = _lineSegment.transform(toWorld);
 671         }
 672         _triangles[0] = triangles[0];
 673         _triangles[1] = triangles[1];
 674     }
 675     virtual void apply(BVHLineGeometry& node)
 676     {
 677         if (node.getType() != BVHLineGeometry::CarrierWire)
 678             return;
 679         SGLineSegmentd lineSegment(node.getLineSegment());
 680         if (!_intersects(lineSegment))
 681             return;
 682
 683         _lineSegment = lineSegment;
 684         _linearVelocity = SGVec3d::zeros();
 685         _angularVelocity = SGVec3d::zeros();
 686         _wire = &node;
 687     }
 688     virtual void apply(BVHStaticGeometry& node)
 689     { }
 690
 691     virtual void apply(const BVHStaticBinary&, const BVHStaticData&) { }
 692     virtual void apply(const BVHStaticTriangle&, const BVHStaticData&) { }
 693
 694     bool _intersects(const SGSphered& sphere) const
 695     {
 696         if (_wire)
 697             return false;
 698         if (intersects(_triangles[0], sphere))
 699             return true;
 700         if (intersects(_triangles[1], sphere))
 701             return true;
 702         return false;
 703     }
 704     bool _intersects(const SGLineSegmentd& lineSegment) const
 705     {
 706         if (_wire)
 707             return false;
 708         if (intersects(_triangles[0], lineSegment))
 709             return true;
 710         if (intersects(_triangles[1], lineSegment))
 711             return true;
 712         return false;
 713     }
 714
 715     const SGLineSegmentd& getLineSegment() const
 716     { return _lineSegment; }
 717     const SGVec3d& getLinearVelocity() const
 718     { return _linearVelocity; }
 719     const SGVec3d& getAngularVelocity() const
 720     { return _angularVelocity; }
 721
 722     const BVHLineGeometry* getWire() const
 723     { return _wire; }
 724
 725 private:
 726     SGLineSegmentd _lineSegment;
 727     SGVec3d _linearVelocity;
 728     SGVec3d _angularVelocity;
 729     const BVHLineGeometry* _wire;
 730
 731     SGTriangled _triangles[2];
 732     double _time;
 733 };
 734
 735 bool FGGroundCache::caught_wire(double t, const SGVec3d pt[4])
 736 {
 737     // Get the wire in question
 738     WireIntersector wireIntersector(pt, t);
 739     if (_localBvhTree)
 740         _localBvhTree->accept(wireIntersector);
 741
 742     _wire = wireIntersector.getWire();
 743     return _wire;
 744 }
 745
 746 class FGGroundCache::WireFinder : public BVHVisitor {
 747 public:
 748     WireFinder(const BVHLineGeometry* wire, const double& t) :
 749         _wire(wire),
 750         _time(t),
 751         _lineSegment(SGVec3d::zeros(), SGVec3d::zeros()),
 752         _linearVelocity(SGVec3d::zeros()),
 753         _angularVelocity(SGVec3d::zeros()),
 754         _haveLineSegment(false)
 755     { }
 756
 757     virtual void apply(BVHGroup& leaf)
 758     {
 759         if (_haveLineSegment)
 760             return;
 761         leaf.traverse(*this);
 762     }
 763     virtual void apply(BVHTransform& transform)
 764     {
 765         if (_haveLineSegment)
 766             return;
 767
 768         transform.traverse(*this);
 769
 770         if (_haveLineSegment) {
 771             _linearVelocity = transform.vecToWorld(_linearVelocity);
 772             _angularVelocity = transform.vecToWorld(_angularVelocity);
 773             _lineSegment = transform.lineSegmentToWorld(_lineSegment);
 774         }
 775     }
 776     virtual void apply(BVHMotionTransform& transform)
 777     {
 778         if (_haveLineSegment)
 779             return;
 780
 781         transform.traverse(*this);
 782
 783         if (_haveLineSegment) {
 784             SGMatrixd toWorld = transform.getToWorldTransform(_time);
 785             _linearVelocity
 786                 += transform.getLinearVelocityAt(_lineSegment.getStart());
 787             _angularVelocity += transform.getAngularVelocity();
 788             _linearVelocity = toWorld.xformVec(_linearVelocity);
 789             _angularVelocity = toWorld.xformVec(_angularVelocity);
 790             _lineSegment = _lineSegment.transform(toWorld);
 791         }
 792     }
 793     virtual void apply(BVHLineGeometry& node)
 794     {
 795         if (_haveLineSegment)
 796             return;
 797         if (_wire != &node)
 798             return;
 799         if (node.getType() != BVHLineGeometry::CarrierWire)
 800             return;
 801         _lineSegment = SGLineSegmentd(node.getLineSegment());
 802         _linearVelocity = SGVec3d::zeros();
 803         _angularVelocity = SGVec3d::zeros();
 804         _haveLineSegment = true;
 805     }
 806     virtual void apply(BVHStaticGeometry&) { }
 807
 808     virtual void apply(const BVHStaticBinary&, const BVHStaticData&) { }
 809     virtual void apply(const BVHStaticTriangle&, const BVHStaticData&) { }
 810
 811     const SGLineSegmentd& getLineSegment() const
 812     { return _lineSegment; }
 813
 814     bool getHaveLineSegment() const
 815     { return _haveLineSegment; }
 816
 817     const SGVec3d& getLinearVelocity() const
 818     { return _linearVelocity; }
 819     const SGVec3d& getAngularVelocity() const
 820     { return _angularVelocity; }
 821
 822 private:
 823     const BVHLineGeometry* _wire;
 824     double _time;
 825
 826     SGLineSegmentd _lineSegment;
 827     SGVec3d _linearVelocity;
 828     SGVec3d _angularVelocity;
 829
 830     bool _haveLineSegment;
 831 };
 832
 833 bool FGGroundCache::get_wire_ends(double t, SGVec3d end[2], SGVec3d vel[2])
 834 {
 835     // Fast return if we do not have an active wire.
 836     if (!_wire)
 837         return false;
 838
 839     // Get the wire in question
 840     WireFinder wireFinder(_wire, t);
 841     if (_localBvhTree)
 842         _localBvhTree->accept(wireFinder);
 843
 844     if (!wireFinder.getHaveLineSegment())
 845         return false;
 846
 847     // prepare the returns
 848     end[0] = wireFinder.getLineSegment().getStart();
 849     end[1] = wireFinder.getLineSegment().getEnd();
 850
 851     // The linear velocity is the one at the start of the line segment ...
 852     vel[0] = wireFinder.getLinearVelocity();
 853     // ... so the end point has the additional cross product.
 854     vel[1] = wireFinder.getLinearVelocity();
 855     vel[1] += cross(wireFinder.getAngularVelocity(),
 856                     wireFinder.getLineSegment().getDirection());
 857
 858     return true;
 859 }
 860
 861 void FGGroundCache::release_wire(void)
 862 {
 863     _wire = 0;
 864 }