Bullet Collision Detection & Physics Library
btConvexHullShape.cpp
Go to the documentation of this file.
1 /*
2 Bullet Continuous Collision Detection and Physics Library
3 Copyright (c) 2003-2009 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 #if defined(_WIN32) || defined(__i386__)
17 #define BT_USE_SSE_IN_API
18 #endif
19 
20 #include "btConvexHullShape.h"
22 
25 #include "btConvexPolyhedron.h"
27 
29 {
31  m_unscaledPoints.resize(numPoints);
32 
33  unsigned char* pointsAddress = (unsigned char*)points;
34 
35  for (int i = 0; i < numPoints; i++)
36  {
37  btScalar* point = (btScalar*)pointsAddress;
38  m_unscaledPoints[i] = btVector3(point[0], point[1], point[2]);
39  pointsAddress += stride;
40  }
41 
43 }
44 
46 {
47  m_localScaling = scaling;
49 }
50 
51 void btConvexHullShape::addPoint(const btVector3& point, bool recalculateLocalAabb)
52 {
54  if (recalculateLocalAabb)
56 }
57 
59 {
60  btVector3 supVec(btScalar(0.), btScalar(0.), btScalar(0.));
61  btScalar maxDot = btScalar(-BT_LARGE_FLOAT);
62 
63  // Here we take advantage of dot(a, b*c) = dot(a*b, c). Note: This is true mathematically, but not numerically.
64  if (0 < m_unscaledPoints.size())
65  {
66  btVector3 scaled = vec * m_localScaling;
67  int index = (int)scaled.maxDot(&m_unscaledPoints[0], m_unscaledPoints.size(), maxDot); // FIXME: may violate encapsulation of m_unscaledPoints
68  return m_unscaledPoints[index] * m_localScaling;
69  }
70 
71  return supVec;
72 }
73 
74 void btConvexHullShape::batchedUnitVectorGetSupportingVertexWithoutMargin(const btVector3* vectors, btVector3* supportVerticesOut, int numVectors) const
75 {
76  btScalar newDot;
77  //use 'w' component of supportVerticesOut?
78  {
79  for (int i = 0; i < numVectors; i++)
80  {
81  supportVerticesOut[i][3] = btScalar(-BT_LARGE_FLOAT);
82  }
83  }
84 
85  for (int j = 0; j < numVectors; j++)
86  {
87  btVector3 vec = vectors[j] * m_localScaling; // dot(a*b,c) = dot(a,b*c)
88  if (0 < m_unscaledPoints.size())
89  {
90  int i = (int)vec.maxDot(&m_unscaledPoints[0], m_unscaledPoints.size(), newDot);
91  supportVerticesOut[j] = getScaledPoint(i);
92  supportVerticesOut[j][3] = newDot;
93  }
94  else
95  supportVerticesOut[j][3] = -BT_LARGE_FLOAT;
96  }
97 }
98 
100 {
102 
103  if (getMargin() != btScalar(0.))
104  {
105  btVector3 vecnorm = vec;
106  if (vecnorm.length2() < (SIMD_EPSILON * SIMD_EPSILON))
107  {
108  vecnorm.setValue(btScalar(-1.), btScalar(-1.), btScalar(-1.));
109  }
110  vecnorm.normalize();
111  supVertex += getMargin() * vecnorm;
112  }
113  return supVertex;
114 }
115 
117 {
119  conv.compute(&m_unscaledPoints[0].getX(), sizeof(btVector3), m_unscaledPoints.size(), 0.f, 0.f);
120  int numVerts = conv.vertices.size();
122  for (int i = 0; i < numVerts; i++)
123  {
125  }
126 }
127 
128 //currently just for debugging (drawing), perhaps future support for algebraic continuous collision detection
129 //Please note that you can debug-draw btConvexHullShape with the Raytracer Demo
131 {
132  return m_unscaledPoints.size();
133 }
134 
136 {
137  return m_unscaledPoints.size();
138 }
139 
140 void btConvexHullShape::getEdge(int i, btVector3& pa, btVector3& pb) const
141 {
142  int index0 = i % m_unscaledPoints.size();
143  int index1 = (i + 1) % m_unscaledPoints.size();
144  pa = getScaledPoint(index0);
145  pb = getScaledPoint(index1);
146 }
147 
149 {
150  vtx = getScaledPoint(i);
151 }
152 
154 {
155  return 0;
156 }
157 
159 {
160  btAssert(0);
161 }
162 
163 //not yet
165 {
166  btAssert(0);
167  return false;
168 }
169 
171 const char* btConvexHullShape::serialize(void* dataBuffer, btSerializer* serializer) const
172 {
173  //int szc = sizeof(btConvexHullShapeData);
174  btConvexHullShapeData* shapeData = (btConvexHullShapeData*)dataBuffer;
176 
177  int numElem = m_unscaledPoints.size();
178  shapeData->m_numUnscaledPoints = numElem;
179 #ifdef BT_USE_DOUBLE_PRECISION
180  shapeData->m_unscaledPointsFloatPtr = 0;
181  shapeData->m_unscaledPointsDoublePtr = numElem ? (btVector3Data*)serializer->getUniquePointer((void*)&m_unscaledPoints[0]) : 0;
182 #else
183  shapeData->m_unscaledPointsFloatPtr = numElem ? (btVector3Data*)serializer->getUniquePointer((void*)&m_unscaledPoints[0]) : 0;
184  shapeData->m_unscaledPointsDoublePtr = 0;
185 #endif
186 
187  if (numElem)
188  {
189  int sz = sizeof(btVector3Data);
190  // int sz2 = sizeof(btVector3DoubleData);
191  // int sz3 = sizeof(btVector3FloatData);
192  btChunk* chunk = serializer->allocate(sz, numElem);
193  btVector3Data* memPtr = (btVector3Data*)chunk->m_oldPtr;
194  for (int i = 0; i < numElem; i++, memPtr++)
195  {
196  m_unscaledPoints[i].serialize(*memPtr);
197  }
198  serializer->finalizeChunk(chunk, btVector3DataName, BT_ARRAY_CODE, (void*)&m_unscaledPoints[0]);
199  }
200 
201  // Fill padding with zeros to appease msan.
202  memset(shapeData->m_padding3, 0, sizeof(shapeData->m_padding3));
203 
204  return "btConvexHullShapeData";
205 }
206 
207 void btConvexHullShape::project(const btTransform& trans, const btVector3& dir, btScalar& minProj, btScalar& maxProj, btVector3& witnesPtMin, btVector3& witnesPtMax) const
208 {
209 #if 1
210  minProj = FLT_MAX;
211  maxProj = -FLT_MAX;
212 
213  int numVerts = m_unscaledPoints.size();
214  for (int i = 0; i < numVerts; i++)
215  {
217  btVector3 pt = trans * vtx;
218  btScalar dp = pt.dot(dir);
219  if (dp < minProj)
220  {
221  minProj = dp;
222  witnesPtMin = pt;
223  }
224  if (dp > maxProj)
225  {
226  maxProj = dp;
227  witnesPtMax = pt;
228  }
229  }
230 #else
231  btVector3 localAxis = dir * trans.getBasis();
232  witnesPtMin = trans(localGetSupportingVertex(localAxis));
233  witnesPtMax = trans(localGetSupportingVertex(-localAxis));
234 
235  minProj = witnesPtMin.dot(dir);
236  maxProj = witnesPtMax.dot(dir);
237 #endif
238 
239  if (minProj > maxProj)
240  {
241  btSwap(minProj, maxProj);
242  btSwap(witnesPtMin, witnesPtMax);
243  }
244 }
@ CONVEX_HULL_SHAPE_PROXYTYPE
float btScalar
The btScalar type abstracts floating point numbers, to easily switch between double and single floati...
Definition: btScalar.h:314
#define BT_LARGE_FLOAT
Definition: btScalar.h:316
#define SIMD_EPSILON
Definition: btScalar.h:543
void btSwap(T &a, T &b)
Definition: btScalar.h:643
#define btAssert(x)
Definition: btScalar.h:153
#define BT_ARRAY_CODE
Definition: btSerializer.h:118
#define btVector3DataName
Definition: btVector3.h:28
#define btVector3Data
Definition: btVector3.h:27
int size() const
return the number of elements in the array
void resize(int newsize, const T &fillData=T())
void push_back(const T &_Val)
void * m_oldPtr
Definition: btSerializer.h:52
Convex hull implementation based on Preparata and Hong See http://code.google.com/p/bullet/issues/det...
btScalar compute(const void *coords, bool doubleCoords, int stride, int count, btScalar shrink, btScalar shrinkClamp)
btAlignedObjectArray< btVector3 > vertices
btConvexHullShape(const btScalar *points=0, int numPoints=0, int stride=sizeof(btVector3))
this constructor optionally takes in a pointer to points.
btAlignedObjectArray< btVector3 > m_unscaledPoints
virtual int getNumPlanes() const
virtual int getNumVertices() const
virtual int getNumEdges() const
virtual void getVertex(int i, btVector3 &vtx) const
virtual bool isInside(const btVector3 &pt, btScalar tolerance) const
virtual void getEdge(int i, btVector3 &pa, btVector3 &pb) const
virtual void project(const btTransform &trans, const btVector3 &dir, btScalar &minProj, btScalar &maxProj, btVector3 &witnesPtMin, btVector3 &witnesPtMax) const
btVector3 getScaledPoint(int i) const
virtual void batchedUnitVectorGetSupportingVertexWithoutMargin(const btVector3 *vectors, btVector3 *supportVerticesOut, int numVectors) const
virtual btVector3 localGetSupportingVertexWithoutMargin(const btVector3 &vec) const
virtual const char * serialize(void *dataBuffer, btSerializer *serializer) const
fills the dataBuffer and returns the struct name (and 0 on failure)
virtual btVector3 localGetSupportingVertex(const btVector3 &vec) const
virtual void getPlane(btVector3 &planeNormal, btVector3 &planeSupport, int i) const
void addPoint(const btVector3 &point, bool recalculateLocalAabb=true)
virtual void setLocalScaling(const btVector3 &scaling)
in case we receive negative scaling
virtual const char * serialize(void *dataBuffer, btSerializer *serializer) const
fills the dataBuffer and returns the struct name (and 0 on failure)
virtual btScalar getMargin() const
The btPolyhedralConvexAabbCachingShape adds aabb caching to the btPolyhedralConvexShape.
virtual btChunk * allocate(size_t size, int numElements)=0
virtual void * getUniquePointer(void *oldPtr)=0
virtual void finalizeChunk(btChunk *chunk, const char *structType, int chunkCode, void *oldPtr)=0
The btTransform class supports rigid transforms with only translation and rotation and no scaling/she...
Definition: btTransform.h:30
btMatrix3x3 & getBasis()
Return the basis matrix for the rotation.
Definition: btTransform.h:108
btVector3 can be used to represent 3D points and vectors.
Definition: btVector3.h:82
btVector3 & normalize()
Normalize this vector x^2 + y^2 + z^2 = 1.
Definition: btVector3.h:303
btScalar dot(const btVector3 &v) const
Return the dot product.
Definition: btVector3.h:229
void setValue(const btScalar &_x, const btScalar &_y, const btScalar &_z)
Definition: btVector3.h:640
long maxDot(const btVector3 *array, long array_count, btScalar &dotOut) const
returns index of maximum dot product between this and vectors in array[]
Definition: btVector3.h:998
btScalar length2() const
Return the length of the vector squared.
Definition: btVector3.h:251
do not change those serialization structures, it requires an updated sBulletDNAstr/sBulletDNAstr64
btVector3DoubleData * m_unscaledPointsDoublePtr
btVector3FloatData * m_unscaledPointsFloatPtr
btConvexInternalShapeData m_convexInternalShapeData