dali-physics/third-party/bullet3/src/BulletCollision/NarrowPhaseCollision/btComputeGjkEpaPenetration.h

   1 /*
   2 Bullet Continuous Collision Detection and Physics Library
   3 Copyright (c) 2003-2014 Erwin Coumans http://bulletphysics.org
   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 #ifndef BT_GJK_EPA_PENETATION_CONVEX_COLLISION_H
  17 #define BT_GJK_EPA_PENETATION_CONVEX_COLLISION_H
  18
  19 #include "LinearMath/btTransform.h"  // Note that btVector3 might be double precision...
  20 #include "btGjkEpa3.h"
  21 #include "btGjkCollisionDescription.h"
  22 #include "BulletCollision/NarrowPhaseCollision/btVoronoiSimplexSolver.h"
  23
  24 template <typename btConvexTemplate>
  25 bool btGjkEpaCalcPenDepth(const btConvexTemplate& a, const btConvexTemplate& b,
  26                                                   const btGjkCollisionDescription& colDesc,
  27                                                   btVector3& v, btVector3& wWitnessOnA, btVector3& wWitnessOnB)
  28 {
  29         (void)v;
  30
  31         //      const btScalar                          radialmargin(btScalar(0.));
  32
  33         btVector3 guessVector(b.getWorldTransform().getOrigin() - a.getWorldTransform().getOrigin());  //?? why not use the GJK input?
  34
  35         btGjkEpaSolver3::sResults results;
  36
  37         if (btGjkEpaSolver3_Penetration(a, b, guessVector, results))
  38
  39         {
  40                 //      debugDraw->drawLine(results.witnesses[1],results.witnesses[1]+results.normal,btVector3(255,0,0));
  41                 //resultOut->addContactPoint(results.normal,results.witnesses[1],-results.depth);
  42                 wWitnessOnA = results.witnesses[0];
  43                 wWitnessOnB = results.witnesses[1];
  44                 v = results.normal;
  45                 return true;
  46         }
  47         else
  48         {
  49                 if (btGjkEpaSolver3_Distance(a, b, guessVector, results))
  50                 {
  51                         wWitnessOnA = results.witnesses[0];
  52                         wWitnessOnB = results.witnesses[1];
  53                         v = results.normal;
  54                         return false;
  55                 }
  56         }
  57         return false;
  58 }
  59
  60 template <typename btConvexTemplate, typename btGjkDistanceTemplate>
  61 int btComputeGjkEpaPenetration(const btConvexTemplate& a, const btConvexTemplate& b, const btGjkCollisionDescription& colDesc, btVoronoiSimplexSolver& simplexSolver, btGjkDistanceTemplate* distInfo)
  62 {
  63         bool m_catchDegeneracies = true;
  64         btScalar m_cachedSeparatingDistance = 0.f;
  65
  66         btScalar distance = btScalar(0.);
  67         btVector3 normalInB(btScalar(0.), btScalar(0.), btScalar(0.));
  68
  69         btVector3 pointOnA, pointOnB;
  70         btTransform localTransA = a.getWorldTransform();
  71         btTransform localTransB = b.getWorldTransform();
  72
  73         btScalar marginA = a.getMargin();
  74         btScalar marginB = b.getMargin();
  75
  76         int m_curIter = 0;
  77         int gGjkMaxIter = colDesc.m_maxGjkIterations;  //this is to catch invalid input, perhaps check for #NaN?
  78         btVector3 m_cachedSeparatingAxis = colDesc.m_firstDir;
  79
  80         bool isValid = false;
  81         bool checkSimplex = false;
  82         bool checkPenetration = true;
  83         int m_degenerateSimplex = 0;
  84
  85         int m_lastUsedMethod = -1;
  86
  87         {
  88                 btScalar squaredDistance = BT_LARGE_FLOAT;
  89                 btScalar delta = btScalar(0.);
  90
  91                 btScalar margin = marginA + marginB;
  92
  93                 simplexSolver.reset();
  94
  95                 for (;;)
  96                 //while (true)
  97                 {
  98                         btVector3 separatingAxisInA = (-m_cachedSeparatingAxis) * localTransA.getBasis();
  99                         btVector3 separatingAxisInB = m_cachedSeparatingAxis * localTransB.getBasis();
 100
 101                         btVector3 pInA = a.getLocalSupportWithoutMargin(separatingAxisInA);
 102                         btVector3 qInB = b.getLocalSupportWithoutMargin(separatingAxisInB);
 103
 104                         btVector3 pWorld = localTransA(pInA);
 105                         btVector3 qWorld = localTransB(qInB);
 106
 107                         btVector3 w = pWorld - qWorld;
 108                         delta = m_cachedSeparatingAxis.dot(w);
 109
 110                         // potential exit, they don't overlap
 111                         if ((delta > btScalar(0.0)) && (delta * delta > squaredDistance * colDesc.m_maximumDistanceSquared))
 112                         {
 113                                 m_degenerateSimplex = 10;
 114                                 checkSimplex = true;
 115                                 //checkPenetration = false;
 116                                 break;
 117                         }
 118
 119                         //exit 0: the new point is already in the simplex, or we didn't come any closer
 120                         if (simplexSolver.inSimplex(w))
 121                         {
 122                                 m_degenerateSimplex = 1;
 123                                 checkSimplex = true;
 124                                 break;
 125                         }
 126                         // are we getting any closer ?
 127                         btScalar f0 = squaredDistance - delta;
 128                         btScalar f1 = squaredDistance * colDesc.m_gjkRelError2;
 129
 130                         if (f0 <= f1)
 131                         {
 132                                 if (f0 <= btScalar(0.))
 133                                 {
 134                                         m_degenerateSimplex = 2;
 135                                 }
 136                                 else
 137                                 {
 138                                         m_degenerateSimplex = 11;
 139                                 }
 140                                 checkSimplex = true;
 141                                 break;
 142                         }
 143
 144                         //add current vertex to simplex
 145                         simplexSolver.addVertex(w, pWorld, qWorld);
 146                         btVector3 newCachedSeparatingAxis;
 147
 148                         //calculate the closest point to the origin (update vector v)
 149                         if (!simplexSolver.closest(newCachedSeparatingAxis))
 150                         {
 151                                 m_degenerateSimplex = 3;
 152                                 checkSimplex = true;
 153                                 break;
 154                         }
 155
 156                         if (newCachedSeparatingAxis.length2() < colDesc.m_gjkRelError2)
 157                         {
 158                                 m_cachedSeparatingAxis = newCachedSeparatingAxis;
 159                                 m_degenerateSimplex = 6;
 160                                 checkSimplex = true;
 161                                 break;
 162                         }
 163
 164                         btScalar previousSquaredDistance = squaredDistance;
 165                         squaredDistance = newCachedSeparatingAxis.length2();
 166 #if 0
 167             ///warning: this termination condition leads to some problems in 2d test case see Bullet/Demos/Box2dDemo
 168             if (squaredDistance>previousSquaredDistance)
 169             {
 170                 m_degenerateSimplex = 7;
 171                 squaredDistance = previousSquaredDistance;
 172                 checkSimplex = false;
 173                 break;
 174             }
 175 #endif  //
 176
 177                         //redundant m_simplexSolver->compute_points(pointOnA, pointOnB);
 178
 179                         //are we getting any closer ?
 180                         if (previousSquaredDistance - squaredDistance <= SIMD_EPSILON * previousSquaredDistance)
 181                         {
 182                                 //                              m_simplexSolver->backup_closest(m_cachedSeparatingAxis);
 183                                 checkSimplex = true;
 184                                 m_degenerateSimplex = 12;
 185
 186                                 break;
 187                         }
 188
 189                         m_cachedSeparatingAxis = newCachedSeparatingAxis;
 190
 191                         //degeneracy, this is typically due to invalid/uninitialized worldtransforms for a btCollisionObject
 192                         if (m_curIter++ > gGjkMaxIter)
 193                         {
 194 #if defined(DEBUG) || defined(_DEBUG)
 195
 196                                 printf("btGjkPairDetector maxIter exceeded:%i\n", m_curIter);
 197                                 printf("sepAxis=(%f,%f,%f), squaredDistance = %f\n",
 198                                            m_cachedSeparatingAxis.getX(),
 199                                            m_cachedSeparatingAxis.getY(),
 200                                            m_cachedSeparatingAxis.getZ(),
 201                                            squaredDistance);
 202 #endif
 203
 204                                 break;
 205                         }
 206
 207                         bool check = (!simplexSolver.fullSimplex());
 208                         //bool check = (!m_simplexSolver->fullSimplex() && squaredDistance > SIMD_EPSILON * m_simplexSolver->maxVertex());
 209
 210                         if (!check)
 211                         {
 212                                 //do we need this backup_closest here ?
 213                                 //                              m_simplexSolver->backup_closest(m_cachedSeparatingAxis);
 214                                 m_degenerateSimplex = 13;
 215                                 break;
 216                         }
 217                 }
 218
 219                 if (checkSimplex)
 220                 {
 221                         simplexSolver.compute_points(pointOnA, pointOnB);
 222                         normalInB = m_cachedSeparatingAxis;
 223
 224                         btScalar lenSqr = m_cachedSeparatingAxis.length2();
 225
 226                         //valid normal
 227                         if (lenSqr < 0.0001)
 228                         {
 229                                 m_degenerateSimplex = 5;
 230                         }
 231                         if (lenSqr > SIMD_EPSILON * SIMD_EPSILON)
 232                         {
 233                                 btScalar rlen = btScalar(1.) / btSqrt(lenSqr);
 234                                 normalInB *= rlen;  //normalize
 235
 236                                 btScalar s = btSqrt(squaredDistance);
 237
 238                                 btAssert(s > btScalar(0.0));
 239                                 pointOnA -= m_cachedSeparatingAxis * (marginA / s);
 240                                 pointOnB += m_cachedSeparatingAxis * (marginB / s);
 241                                 distance = ((btScalar(1.) / rlen) - margin);
 242                                 isValid = true;
 243
 244                                 m_lastUsedMethod = 1;
 245                         }
 246                         else
 247                         {
 248                                 m_lastUsedMethod = 2;
 249                         }
 250                 }
 251
 252                 bool catchDegeneratePenetrationCase =
 253                         (m_catchDegeneracies && m_degenerateSimplex && ((distance + margin) < 0.01));
 254
 255                 //if (checkPenetration && !isValid)
 256                 if (checkPenetration && (!isValid || catchDegeneratePenetrationCase))
 257                 {
 258                         //penetration case
 259
 260                         //if there is no way to handle penetrations, bail out
 261
 262                         // Penetration depth case.
 263                         btVector3 tmpPointOnA, tmpPointOnB;
 264
 265                         m_cachedSeparatingAxis.setZero();
 266
 267                         bool isValid2 = btGjkEpaCalcPenDepth(a, b,
 268                                                                                                  colDesc,
 269                                                                                                  m_cachedSeparatingAxis, tmpPointOnA, tmpPointOnB);
 270
 271                         if (isValid2)
 272                         {
 273                                 btVector3 tmpNormalInB = tmpPointOnB - tmpPointOnA;
 274                                 btScalar lenSqr = tmpNormalInB.length2();
 275                                 if (lenSqr <= (SIMD_EPSILON * SIMD_EPSILON))
 276                                 {
 277                                         tmpNormalInB = m_cachedSeparatingAxis;
 278                                         lenSqr = m_cachedSeparatingAxis.length2();
 279                                 }
 280
 281                                 if (lenSqr > (SIMD_EPSILON * SIMD_EPSILON))
 282                                 {
 283                                         tmpNormalInB /= btSqrt(lenSqr);
 284                                         btScalar distance2 = -(tmpPointOnA - tmpPointOnB).length();
 285                                         //only replace valid penetrations when the result is deeper (check)
 286                                         if (!isValid || (distance2 < distance))
 287                                         {
 288                                                 distance = distance2;
 289                                                 pointOnA = tmpPointOnA;
 290                                                 pointOnB = tmpPointOnB;
 291                                                 normalInB = tmpNormalInB;
 292
 293                                                 isValid = true;
 294                                                 m_lastUsedMethod = 3;
 295                                         }
 296                                         else
 297                                         {
 298                                                 m_lastUsedMethod = 8;
 299                                         }
 300                                 }
 301                                 else
 302                                 {
 303                                         m_lastUsedMethod = 9;
 304                                 }
 305                         }
 306                         else
 307
 308                         {
 309                                 ///this is another degenerate case, where the initial GJK calculation reports a degenerate case
 310                                 ///EPA reports no penetration, and the second GJK (using the supporting vector without margin)
 311                                 ///reports a valid positive distance. Use the results of the second GJK instead of failing.
 312                                 ///thanks to Jacob.Langford for the reproduction case
 313                                 ///http://code.google.com/p/bullet/issues/detail?id=250
 314
 315                                 if (m_cachedSeparatingAxis.length2() > btScalar(0.))
 316                                 {
 317                                         btScalar distance2 = (tmpPointOnA - tmpPointOnB).length() - margin;
 318                                         //only replace valid distances when the distance is less
 319                                         if (!isValid || (distance2 < distance))
 320                                         {
 321                                                 distance = distance2;
 322                                                 pointOnA = tmpPointOnA;
 323                                                 pointOnB = tmpPointOnB;
 324                                                 pointOnA -= m_cachedSeparatingAxis * marginA;
 325                                                 pointOnB += m_cachedSeparatingAxis * marginB;
 326                                                 normalInB = m_cachedSeparatingAxis;
 327                                                 normalInB.normalize();
 328
 329                                                 isValid = true;
 330                                                 m_lastUsedMethod = 6;
 331                                         }
 332                                         else
 333                                         {
 334                                                 m_lastUsedMethod = 5;
 335                                         }
 336                                 }
 337                         }
 338                 }
 339         }
 340
 341         if (isValid && ((distance < 0) || (distance * distance < colDesc.m_maximumDistanceSquared)))
 342         {
 343                 m_cachedSeparatingAxis = normalInB;
 344                 m_cachedSeparatingDistance = distance;
 345                 distInfo->m_distance = distance;
 346                 distInfo->m_normalBtoA = normalInB;
 347                 distInfo->m_pointOnB = pointOnB;
 348                 distInfo->m_pointOnA = pointOnB + normalInB * distance;
 349                 return 0;
 350         }
 351         return -m_lastUsedMethod;
 352 }
 353
 354 #endif  //BT_GJK_EPA_PENETATION_CONVEX_COLLISION_H