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 #include "btGjkPairDetector.h"
17 #include "BulletCollision/CollisionShapes/btConvexShape.h"
18 #include "BulletCollision/NarrowPhaseCollision/btSimplexSolverInterface.h"
19 #include "BulletCollision/NarrowPhaseCollision/btConvexPenetrationDepthSolver.h"
20
21
22
23 #if defined(DEBUG) || defined (_DEBUG)
24 //#define TEST_NON_VIRTUAL 1
25 #include <stdio.h> //for debug printf
26 #ifdef __SPU__
27 #include <spu_printf.h>
28 #define printf spu_printf
29 //#define DEBUG_SPU_COLLISION_DETECTION 1
30 #endif //__SPU__
31 #endif
32
33 //must be above the machine epsilon
34 #define REL_ERROR2 btScalar(1.0e-6)
35
36 //temp globals, to improve GJK/EPA/penetration calculations
37 int gNumDeepPenetrationChecks = 0;
38 int gNumGjkChecks = 0;
39
40
btGjkPairDetector(const btConvexShape * objectA,const btConvexShape * objectB,btSimplexSolverInterface * simplexSolver,btConvexPenetrationDepthSolver * penetrationDepthSolver)41 btGjkPairDetector::btGjkPairDetector(const btConvexShape* objectA,const btConvexShape* objectB,btSimplexSolverInterface* simplexSolver,btConvexPenetrationDepthSolver* penetrationDepthSolver)
42 :m_cachedSeparatingAxis(btScalar(0.),btScalar(1.),btScalar(0.)),
43 m_penetrationDepthSolver(penetrationDepthSolver),
44 m_simplexSolver(simplexSolver),
45 m_minkowskiA(objectA),
46 m_minkowskiB(objectB),
47 m_shapeTypeA(objectA->getShapeType()),
48 m_shapeTypeB(objectB->getShapeType()),
49 m_marginA(objectA->getMargin()),
50 m_marginB(objectB->getMargin()),
51 m_ignoreMargin(false),
52 m_lastUsedMethod(-1),
53 m_catchDegeneracies(1)
54 {
55 }
btGjkPairDetector(const btConvexShape * objectA,const btConvexShape * objectB,int shapeTypeA,int shapeTypeB,btScalar marginA,btScalar marginB,btSimplexSolverInterface * simplexSolver,btConvexPenetrationDepthSolver * penetrationDepthSolver)56 btGjkPairDetector::btGjkPairDetector(const btConvexShape* objectA,const btConvexShape* objectB,int shapeTypeA,int shapeTypeB,btScalar marginA, btScalar marginB, btSimplexSolverInterface* simplexSolver,btConvexPenetrationDepthSolver* penetrationDepthSolver)
57 :m_cachedSeparatingAxis(btScalar(0.),btScalar(1.),btScalar(0.)),
58 m_penetrationDepthSolver(penetrationDepthSolver),
59 m_simplexSolver(simplexSolver),
60 m_minkowskiA(objectA),
61 m_minkowskiB(objectB),
62 m_shapeTypeA(shapeTypeA),
63 m_shapeTypeB(shapeTypeB),
64 m_marginA(marginA),
65 m_marginB(marginB),
66 m_ignoreMargin(false),
67 m_lastUsedMethod(-1),
68 m_catchDegeneracies(1)
69 {
70 }
71
getClosestPoints(const ClosestPointInput & input,Result & output,class btIDebugDraw * debugDraw,bool swapResults)72 void btGjkPairDetector::getClosestPoints(const ClosestPointInput& input,Result& output,class btIDebugDraw* debugDraw,bool swapResults)
73 {
74 (void)swapResults;
75
76 getClosestPointsNonVirtual(input,output,debugDraw);
77 }
78
79 #ifdef __SPU__
getClosestPointsNonVirtual(const ClosestPointInput & input,Result & output,class btIDebugDraw * debugDraw)80 void btGjkPairDetector::getClosestPointsNonVirtual(const ClosestPointInput& input,Result& output,class btIDebugDraw* debugDraw)
81 #else
82 void btGjkPairDetector::getClosestPointsNonVirtual(const ClosestPointInput& input,Result& output,class btIDebugDraw* debugDraw)
83 #endif
84 {
85 m_cachedSeparatingDistance = 0.f;
86
87 btScalar distance=btScalar(0.);
88 btVector3 normalInB(btScalar(0.),btScalar(0.),btScalar(0.));
89 btVector3 pointOnA,pointOnB;
90 btTransform localTransA = input.m_transformA;
91 btTransform localTransB = input.m_transformB;
92 btVector3 positionOffset = (localTransA.getOrigin() + localTransB.getOrigin()) * btScalar(0.5);
93 localTransA.getOrigin() -= positionOffset;
94 localTransB.getOrigin() -= positionOffset;
95
96 bool check2d = m_minkowskiA->isConvex2d() && m_minkowskiB->isConvex2d();
97
98 btScalar marginA = m_marginA;
99 btScalar marginB = m_marginB;
100
101 gNumGjkChecks++;
102
103 #ifdef DEBUG_SPU_COLLISION_DETECTION
104 spu_printf("inside gjk\n");
105 #endif
106 //for CCD we don't use margins
107 if (m_ignoreMargin)
108 {
109 marginA = btScalar(0.);
110 marginB = btScalar(0.);
111 #ifdef DEBUG_SPU_COLLISION_DETECTION
112 spu_printf("ignoring margin\n");
113 #endif
114 }
115
116 m_curIter = 0;
117 int gGjkMaxIter = 1000;//this is to catch invalid input, perhaps check for #NaN?
118 m_cachedSeparatingAxis.setValue(0,1,0);
119
120 bool isValid = false;
121 bool checkSimplex = false;
122 bool checkPenetration = true;
123 m_degenerateSimplex = 0;
124
125 m_lastUsedMethod = -1;
126
127 {
128 btScalar squaredDistance = BT_LARGE_FLOAT;
129 btScalar delta = btScalar(0.);
130
131 btScalar margin = marginA + marginB;
132
133
134
135 m_simplexSolver->reset();
136
137 for ( ; ; )
138 //while (true)
139 {
140
141 btVector3 seperatingAxisInA = (-m_cachedSeparatingAxis)* input.m_transformA.getBasis();
142 btVector3 seperatingAxisInB = m_cachedSeparatingAxis* input.m_transformB.getBasis();
143
144 #if 1
145
146 btVector3 pInA = m_minkowskiA->localGetSupportVertexWithoutMarginNonVirtual(seperatingAxisInA);
147 btVector3 qInB = m_minkowskiB->localGetSupportVertexWithoutMarginNonVirtual(seperatingAxisInB);
148
149 // btVector3 pInA = localGetSupportingVertexWithoutMargin(m_shapeTypeA, m_minkowskiA, seperatingAxisInA,input.m_convexVertexData[0]);//, &featureIndexA);
150 // btVector3 qInB = localGetSupportingVertexWithoutMargin(m_shapeTypeB, m_minkowskiB, seperatingAxisInB,input.m_convexVertexData[1]);//, &featureIndexB);
151
152 #else
153 #ifdef __SPU__
154 btVector3 pInA = m_minkowskiA->localGetSupportVertexWithoutMarginNonVirtual(seperatingAxisInA);
155 btVector3 qInB = m_minkowskiB->localGetSupportVertexWithoutMarginNonVirtual(seperatingAxisInB);
156 #else
157 btVector3 pInA = m_minkowskiA->localGetSupportingVertexWithoutMargin(seperatingAxisInA);
158 btVector3 qInB = m_minkowskiB->localGetSupportingVertexWithoutMargin(seperatingAxisInB);
159 #ifdef TEST_NON_VIRTUAL
160 btVector3 pInAv = m_minkowskiA->localGetSupportingVertexWithoutMargin(seperatingAxisInA);
161 btVector3 qInBv = m_minkowskiB->localGetSupportingVertexWithoutMargin(seperatingAxisInB);
162 btAssert((pInAv-pInA).length() < 0.0001);
163 btAssert((qInBv-qInB).length() < 0.0001);
164 #endif //
165 #endif //__SPU__
166 #endif
167
168
169 btVector3 pWorld = localTransA(pInA);
170 btVector3 qWorld = localTransB(qInB);
171
172 #ifdef DEBUG_SPU_COLLISION_DETECTION
173 spu_printf("got local supporting vertices\n");
174 #endif
175
176 if (check2d)
177 {
178 pWorld[2] = 0.f;
179 qWorld[2] = 0.f;
180 }
181
182 btVector3 w = pWorld - qWorld;
183 delta = m_cachedSeparatingAxis.dot(w);
184
185 // potential exit, they don't overlap
186 if ((delta > btScalar(0.0)) && (delta * delta > squaredDistance * input.m_maximumDistanceSquared))
187 {
188 m_degenerateSimplex = 10;
189 checkSimplex=true;
190 //checkPenetration = false;
191 break;
192 }
193
194 //exit 0: the new point is already in the simplex, or we didn't come any closer
195 if (m_simplexSolver->inSimplex(w))
196 {
197 m_degenerateSimplex = 1;
198 checkSimplex = true;
199 break;
200 }
201 // are we getting any closer ?
202 btScalar f0 = squaredDistance - delta;
203 btScalar f1 = squaredDistance * REL_ERROR2;
204
205 if (f0 <= f1)
206 {
207 if (f0 <= btScalar(0.))
208 {
209 m_degenerateSimplex = 2;
210 } else
211 {
212 m_degenerateSimplex = 11;
213 }
214 checkSimplex = true;
215 break;
216 }
217
218 #ifdef DEBUG_SPU_COLLISION_DETECTION
219 spu_printf("addVertex 1\n");
220 #endif
221 //add current vertex to simplex
222 m_simplexSolver->addVertex(w, pWorld, qWorld);
223 #ifdef DEBUG_SPU_COLLISION_DETECTION
224 spu_printf("addVertex 2\n");
225 #endif
226 btVector3 newCachedSeparatingAxis;
227
228 //calculate the closest point to the origin (update vector v)
229 if (!m_simplexSolver->closest(newCachedSeparatingAxis))
230 {
231 m_degenerateSimplex = 3;
232 checkSimplex = true;
233 break;
234 }
235
236 if(newCachedSeparatingAxis.length2()<REL_ERROR2)
237 {
238 m_cachedSeparatingAxis = newCachedSeparatingAxis;
239 m_degenerateSimplex = 6;
240 checkSimplex = true;
241 break;
242 }
243
244 btScalar previousSquaredDistance = squaredDistance;
245 squaredDistance = newCachedSeparatingAxis.length2();
246 #if 0
247 ///warning: this termination condition leads to some problems in 2d test case see Bullet/Demos/Box2dDemo
248 if (squaredDistance>previousSquaredDistance)
249 {
250 m_degenerateSimplex = 7;
251 squaredDistance = previousSquaredDistance;
252 checkSimplex = false;
253 break;
254 }
255 #endif //
256
257
258 //redundant m_simplexSolver->compute_points(pointOnA, pointOnB);
259
260 //are we getting any closer ?
261 if (previousSquaredDistance - squaredDistance <= SIMD_EPSILON * previousSquaredDistance)
262 {
263 // m_simplexSolver->backup_closest(m_cachedSeparatingAxis);
264 checkSimplex = true;
265 m_degenerateSimplex = 12;
266
267 break;
268 }
269
270 m_cachedSeparatingAxis = newCachedSeparatingAxis;
271
272 //degeneracy, this is typically due to invalid/uninitialized worldtransforms for a btCollisionObject
273 if (m_curIter++ > gGjkMaxIter)
274 {
275 #if defined(DEBUG) || defined (_DEBUG) || defined (DEBUG_SPU_COLLISION_DETECTION)
276
277 printf("btGjkPairDetector maxIter exceeded:%i\n",m_curIter);
278 printf("sepAxis=(%f,%f,%f), squaredDistance = %f, shapeTypeA=%i,shapeTypeB=%i\n",
279 m_cachedSeparatingAxis.getX(),
280 m_cachedSeparatingAxis.getY(),
281 m_cachedSeparatingAxis.getZ(),
282 squaredDistance,
283 m_minkowskiA->getShapeType(),
284 m_minkowskiB->getShapeType());
285
286 #endif
287 break;
288
289 }
290
291
292 bool check = (!m_simplexSolver->fullSimplex());
293 //bool check = (!m_simplexSolver->fullSimplex() && squaredDistance > SIMD_EPSILON * m_simplexSolver->maxVertex());
294
295 if (!check)
296 {
297 //do we need this backup_closest here ?
298 // m_simplexSolver->backup_closest(m_cachedSeparatingAxis);
299 m_degenerateSimplex = 13;
300 break;
301 }
302 }
303
304 if (checkSimplex)
305 {
306 m_simplexSolver->compute_points(pointOnA, pointOnB);
307 normalInB = m_cachedSeparatingAxis;
308 btScalar lenSqr =m_cachedSeparatingAxis.length2();
309
310 //valid normal
311 if (lenSqr < 0.0001)
312 {
313 m_degenerateSimplex = 5;
314 }
315 if (lenSqr > SIMD_EPSILON*SIMD_EPSILON)
316 {
317 btScalar rlen = btScalar(1.) / btSqrt(lenSqr );
318 normalInB *= rlen; //normalize
319 btScalar s = btSqrt(squaredDistance);
320
321 btAssert(s > btScalar(0.0));
322 pointOnA -= m_cachedSeparatingAxis * (marginA / s);
323 pointOnB += m_cachedSeparatingAxis * (marginB / s);
324 distance = ((btScalar(1.)/rlen) - margin);
325 isValid = true;
326
327 m_lastUsedMethod = 1;
328 } else
329 {
330 m_lastUsedMethod = 2;
331 }
332 }
333
334 bool catchDegeneratePenetrationCase =
335 (m_catchDegeneracies && m_penetrationDepthSolver && m_degenerateSimplex && ((distance+margin) < 0.01));
336
337 //if (checkPenetration && !isValid)
338 if (checkPenetration && (!isValid || catchDegeneratePenetrationCase ))
339 {
340 //penetration case
341
342 //if there is no way to handle penetrations, bail out
343 if (m_penetrationDepthSolver)
344 {
345 // Penetration depth case.
346 btVector3 tmpPointOnA,tmpPointOnB;
347
348 gNumDeepPenetrationChecks++;
349 m_cachedSeparatingAxis.setZero();
350
351 bool isValid2 = m_penetrationDepthSolver->calcPenDepth(
352 *m_simplexSolver,
353 m_minkowskiA,m_minkowskiB,
354 localTransA,localTransB,
355 m_cachedSeparatingAxis, tmpPointOnA, tmpPointOnB,
356 debugDraw,input.m_stackAlloc
357 );
358
359
360 if (isValid2)
361 {
362 btVector3 tmpNormalInB = tmpPointOnB-tmpPointOnA;
363 btScalar lenSqr = tmpNormalInB.length2();
364 if (lenSqr <= (SIMD_EPSILON*SIMD_EPSILON))
365 {
366 tmpNormalInB = m_cachedSeparatingAxis;
367 lenSqr = m_cachedSeparatingAxis.length2();
368 }
369
370 if (lenSqr > (SIMD_EPSILON*SIMD_EPSILON))
371 {
372 tmpNormalInB /= btSqrt(lenSqr);
373 btScalar distance2 = -(tmpPointOnA-tmpPointOnB).length();
374 //only replace valid penetrations when the result is deeper (check)
375 if (!isValid || (distance2 < distance))
376 {
377 distance = distance2;
378 pointOnA = tmpPointOnA;
379 pointOnB = tmpPointOnB;
380 normalInB = tmpNormalInB;
381 isValid = true;
382 m_lastUsedMethod = 3;
383 } else
384 {
385 m_lastUsedMethod = 8;
386 }
387 } else
388 {
389 m_lastUsedMethod = 9;
390 }
391 } else
392
393 {
394 ///this is another degenerate case, where the initial GJK calculation reports a degenerate case
395 ///EPA reports no penetration, and the second GJK (using the supporting vector without margin)
396 ///reports a valid positive distance. Use the results of the second GJK instead of failing.
397 ///thanks to Jacob.Langford for the reproduction case
398 ///http://code.google.com/p/bullet/issues/detail?id=250
399
400
401 if (m_cachedSeparatingAxis.length2() > btScalar(0.))
402 {
403 btScalar distance2 = (tmpPointOnA-tmpPointOnB).length()-margin;
404 //only replace valid distances when the distance is less
405 if (!isValid || (distance2 < distance))
406 {
407 distance = distance2;
408 pointOnA = tmpPointOnA;
409 pointOnB = tmpPointOnB;
410 pointOnA -= m_cachedSeparatingAxis * marginA ;
411 pointOnB += m_cachedSeparatingAxis * marginB ;
412 normalInB = m_cachedSeparatingAxis;
413 normalInB.normalize();
414 isValid = true;
415 m_lastUsedMethod = 6;
416 } else
417 {
418 m_lastUsedMethod = 5;
419 }
420 }
421 }
422
423 }
424
425 }
426 }
427
428
429
430 if (isValid && ((distance < 0) || (distance*distance < input.m_maximumDistanceSquared)))
431 {
432 #if 0
433 ///some debugging
434 // if (check2d)
435 {
436 printf("n = %2.3f,%2.3f,%2.3f. ",normalInB[0],normalInB[1],normalInB[2]);
437 printf("distance = %2.3f exit=%d deg=%d\n",distance,m_lastUsedMethod,m_degenerateSimplex);
438 }
439 #endif
440
441 m_cachedSeparatingAxis = normalInB;
442 m_cachedSeparatingDistance = distance;
443
444 output.addContactPoint(
445 normalInB,
446 pointOnB+positionOffset,
447 distance);
448
449 }
450
451
452 }
453
454
455
456
457
458