src/BulletCollision/NarrowPhaseCollision/btSubSimplexConvexCast.cpp

   1 /*
   2 Bullet Continuous Collision Detection and Physics Library
   3 Copyright (c) 2003-2006 Erwin Coumans  http://continuousphysics.com/Bullet/
   4
   5 This software is provided 'as-is', without any express or implied warranty.
   6 In no event will the authors be held liable for any damages arising from the use of this software.
   7 Permission is granted to anyone to use this software for any purpose,
   8 including commercial applications, and to alter it and redistribute it freely,
   9 subject to the following restrictions:
  10
  11 1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
  12 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
  13 3. This notice may not be removed or altered from any source distribution.
  14 */
  15
  16
  17 #include "btSubSimplexConvexCast.h"
  18 #include "BulletCollision/CollisionShapes/btConvexShape.h"
  19
  20 #include "BulletCollision/CollisionShapes/btMinkowskiSumShape.h"
  21 #include "BulletCollision/NarrowPhaseCollision/btSimplexSolverInterface.h"
  22 #include "btPointCollector.h"
  23 #include "LinearMath/btTransformUtil.h"
  24
  25 btSubsimplexConvexCast::btSubsimplexConvexCast (const btConvexShape* convexA,const btConvexShape* convexB,btSimplexSolverInterface* simplexSolver)
  26 :m_simplexSolver(simplexSolver),
  27 m_convexA(convexA),m_convexB(convexB)
  28 {
  29 }
  30
  31 ///Typically the conservative advancement reaches solution in a few iterations, clip it to 32 for degenerate cases.
  32 ///See discussion about this here http://continuousphysics.com/Bullet/phpBB2/viewtopic.php?t=565
  33 #ifdef BT_USE_DOUBLE_PRECISION
  34 #define MAX_ITERATIONS 64
  35 #else
  36 #define MAX_ITERATIONS 32
  37 #endif
  38 bool    btSubsimplexConvexCast::calcTimeOfImpact(
  39                 const btTransform& fromA,
  40                 const btTransform& toA,
  41                 const btTransform& fromB,
  42                 const btTransform& toB,
  43                 CastResult& result)
  44 {
  45
  46         m_simplexSolver->reset();
  47
  48         btVector3 linVelA,linVelB;
  49         linVelA = toA.getOrigin()-fromA.getOrigin();
  50         linVelB = toB.getOrigin()-fromB.getOrigin();
  51
  52         btScalar lambda = btScalar(0.);
  53
  54         btTransform interpolatedTransA = fromA;
  55         btTransform interpolatedTransB = fromB;
  56
  57         ///take relative motion
  58         btVector3 r = (linVelA-linVelB);
  59         btVector3 v;
  60
  61         btVector3 supVertexA = fromA(m_convexA->localGetSupportingVertex(-r*fromA.getBasis()));
  62         btVector3 supVertexB = fromB(m_convexB->localGetSupportingVertex(r*fromB.getBasis()));
  63         v = supVertexA-supVertexB;
  64         int maxIter = MAX_ITERATIONS;
  65
  66         btVector3 n;
  67         n.setValue(btScalar(0.),btScalar(0.),btScalar(0.));
  68         bool hasResult = false;
  69         btVector3 c;
  70
  71         btScalar lastLambda = lambda;
  72
  73
  74         btScalar dist2 = v.length2();
  75 #ifdef BT_USE_DOUBLE_PRECISION
  76         btScalar epsilon = btScalar(0.0001);
  77 #else
  78         btScalar epsilon = btScalar(0.0001);
  79 #endif //BT_USE_DOUBLE_PRECISION
  80         btVector3       w,p;
  81         btScalar VdotR;
  82
  83         while ( (dist2 > epsilon) && maxIter--)
  84         {
  85                 supVertexA = interpolatedTransA(m_convexA->localGetSupportingVertex(-v*interpolatedTransA.getBasis()));
  86                 supVertexB = interpolatedTransB(m_convexB->localGetSupportingVertex(v*interpolatedTransB.getBasis()));
  87                 w = supVertexA-supVertexB;
  88
  89                 btScalar VdotW = v.dot(w);
  90
  91                 if (lambda > btScalar(1.0))
  92                 {
  93                         return false;
  94                 }
  95
  96                 if ( VdotW > btScalar(0.))
  97                 {
  98                         VdotR = v.dot(r);
  99
 100                         if (VdotR >= -(SIMD_EPSILON*SIMD_EPSILON))
 101                                 return false;
 102                         else
 103                         {
 104                                 lambda = lambda - VdotW / VdotR;
 105                                 //interpolate to next lambda
 106                                 //      x = s + lambda * r;
 107                                 interpolatedTransA.getOrigin().setInterpolate3(fromA.getOrigin(),toA.getOrigin(),lambda);
 108                                 interpolatedTransB.getOrigin().setInterpolate3(fromB.getOrigin(),toB.getOrigin(),lambda);
 109                                 //m_simplexSolver->reset();
 110                                 //check next line
 111                                  w = supVertexA-supVertexB;
 112                                 lastLambda = lambda;
 113                                 n = v;
 114                                 hasResult = true;
 115                         }
 116                 }
 117                 ///Just like regular GJK only add the vertex if it isn't already (close) to current vertex, it would lead to divisions by zero and NaN etc.
 118                 if (!m_simplexSolver->inSimplex(w))
 119                         m_simplexSolver->addVertex( w, supVertexA , supVertexB);
 120
 121                 if (m_simplexSolver->closest(v))
 122                 {
 123                         dist2 = v.length2();
 124                         hasResult = true;
 125                         //todo: check this normal for validity
 126                         //n=v;
 127                         //printf("V=%f , %f, %f\n",v[0],v[1],v[2]);
 128                         //printf("DIST2=%f\n",dist2);
 129                         //printf("numverts = %i\n",m_simplexSolver->numVertices());
 130                 } else
 131                 {
 132                         dist2 = btScalar(0.);
 133                 }
 134         }
 135
 136         //int numiter = MAX_ITERATIONS - maxIter;
 137 //      printf("number of iterations: %d", numiter);
 138
 139         //don't report a time of impact when moving 'away' from the hitnormal
 140
 141
 142         result.m_fraction = lambda;
 143         if (n.length2() >= (SIMD_EPSILON*SIMD_EPSILON))
 144                 result.m_normal = n.normalized();
 145         else
 146                 result.m_normal = btVector3(btScalar(0.0), btScalar(0.0), btScalar(0.0));
 147
 148         //don't report time of impact for motion away from the contact normal (or causes minor penetration)
 149         if (result.m_normal.dot(r)>=-result.m_allowedPenetration)
 150                 return false;
 151
 152         btVector3 hitA,hitB;
 153         m_simplexSolver->compute_points(hitA,hitB);
 154         result.m_hitPoint=hitB;
 155         return true;
 156 }
 157
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