Bullet Collision Detection & Physics Library
btConvexPolyhedron.cpp
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1 /*
2 Bullet Continuous Collision Detection and Physics Library
3 Copyright (c) 2011 Advanced Micro Devices, Inc. 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 
20 
21 #include "btConvexPolyhedron.h"
22 #include "LinearMath/btHashMap.h"
23 
24 
26 {
27 
28 }
30 {
31 
32 }
33 
34 
35 inline bool IsAlmostZero(const btVector3& v)
36 {
37  if(btFabs(v.x())>1e-6 || btFabs(v.y())>1e-6 || btFabs(v.z())>1e-6) return false;
38  return true;
39 }
40 
42 {
43  btInternalVertexPair(short int v0,short int v1)
44  :m_v0(v0),
45  m_v1(v1)
46  {
47  if (m_v1>m_v0)
48  btSwap(m_v0,m_v1);
49  }
50  short int m_v0;
51  short int m_v1;
52  int getHash() const
53  {
54  return m_v0+(m_v1<<16);
55  }
56  bool equals(const btInternalVertexPair& other) const
57  {
58  return m_v0==other.m_v0 && m_v1==other.m_v1;
59  }
60 };
61 
63 {
65  :m_face0(-1),
66  m_face1(-1)
67  {
68  }
69  short int m_face0;
70  short int m_face1;
71 };
72 
73 //
74 
75 #ifdef TEST_INTERNAL_OBJECTS
77 {
78  for(int p=0;p<8;p++)
79  {
80  btVector3 LocalPt;
81  if(p==0) LocalPt = m_localCenter + btVector3(m_extents[0], m_extents[1], m_extents[2]);
82  else if(p==1) LocalPt = m_localCenter + btVector3(m_extents[0], m_extents[1], -m_extents[2]);
83  else if(p==2) LocalPt = m_localCenter + btVector3(m_extents[0], -m_extents[1], m_extents[2]);
84  else if(p==3) LocalPt = m_localCenter + btVector3(m_extents[0], -m_extents[1], -m_extents[2]);
85  else if(p==4) LocalPt = m_localCenter + btVector3(-m_extents[0], m_extents[1], m_extents[2]);
86  else if(p==5) LocalPt = m_localCenter + btVector3(-m_extents[0], m_extents[1], -m_extents[2]);
87  else if(p==6) LocalPt = m_localCenter + btVector3(-m_extents[0], -m_extents[1], m_extents[2]);
88  else if(p==7) LocalPt = m_localCenter + btVector3(-m_extents[0], -m_extents[1], -m_extents[2]);
89 
90  for(int i=0;i<m_faces.size();i++)
91  {
92  const btVector3 Normal(m_faces[i].m_plane[0], m_faces[i].m_plane[1], m_faces[i].m_plane[2]);
93  const btScalar d = LocalPt.dot(Normal) + m_faces[i].m_plane[3];
94  if(d>0.0f)
95  return false;
96  }
97  }
98  return true;
99 }
100 #endif
101 
103 {
104 
106 
107  btScalar TotalArea = 0.0f;
108 
109  m_localCenter.setValue(0, 0, 0);
110  for(int i=0;i<m_faces.size();i++)
111  {
112  int numVertices = m_faces[i].m_indices.size();
113  int NbTris = numVertices;
114  for(int j=0;j<NbTris;j++)
115  {
116  int k = (j+1)%numVertices;
117  btInternalVertexPair vp(m_faces[i].m_indices[j],m_faces[i].m_indices[k]);
118  btInternalEdge* edptr = edges.find(vp);
119  btVector3 edge = m_vertices[vp.m_v1]-m_vertices[vp.m_v0];
120  edge.normalize();
121 
122  bool found = false;
123 
124  for (int p=0;p<m_uniqueEdges.size();p++)
125  {
126 
127  if (IsAlmostZero(m_uniqueEdges[p]-edge) ||
128  IsAlmostZero(m_uniqueEdges[p]+edge))
129  {
130  found = true;
131  break;
132  }
133  }
134 
135  if (!found)
136  {
137  m_uniqueEdges.push_back(edge);
138  }
139 
140  if (edptr)
141  {
142  btAssert(edptr->m_face0>=0);
143  btAssert(edptr->m_face1<0);
144  edptr->m_face1 = i;
145  } else
146  {
147  btInternalEdge ed;
148  ed.m_face0 = i;
149  edges.insert(vp,ed);
150  }
151  }
152  }
153 
154 #ifdef USE_CONNECTED_FACES
155  for(int i=0;i<m_faces.size();i++)
156  {
157  int numVertices = m_faces[i].m_indices.size();
158  m_faces[i].m_connectedFaces.resize(numVertices);
159 
160  for(int j=0;j<numVertices;j++)
161  {
162  int k = (j+1)%numVertices;
163  btInternalVertexPair vp(m_faces[i].m_indices[j],m_faces[i].m_indices[k]);
164  btInternalEdge* edptr = edges.find(vp);
165  btAssert(edptr);
166  btAssert(edptr->m_face0>=0);
167  btAssert(edptr->m_face1>=0);
168 
169  int connectedFace = (edptr->m_face0==i)?edptr->m_face1:edptr->m_face0;
170  m_faces[i].m_connectedFaces[j] = connectedFace;
171  }
172  }
173 #endif//USE_CONNECTED_FACES
174 
175  for(int i=0;i<m_faces.size();i++)
176  {
177  int numVertices = m_faces[i].m_indices.size();
178  int NbTris = numVertices-2;
179 
180  const btVector3& p0 = m_vertices[m_faces[i].m_indices[0]];
181  for(int j=1;j<=NbTris;j++)
182  {
183  int k = (j+1)%numVertices;
184  const btVector3& p1 = m_vertices[m_faces[i].m_indices[j]];
185  const btVector3& p2 = m_vertices[m_faces[i].m_indices[k]];
186  btScalar Area = ((p0 - p1).cross(p0 - p2)).length() * 0.5f;
187  btVector3 Center = (p0+p1+p2)/3.0f;
188  m_localCenter += Area * Center;
189  TotalArea += Area;
190  }
191  }
192  m_localCenter /= TotalArea;
193 
194 
195 
196 
197 #ifdef TEST_INTERNAL_OBJECTS
198  if(1)
199  {
200  m_radius = FLT_MAX;
201  for(int i=0;i<m_faces.size();i++)
202  {
203  const btVector3 Normal(m_faces[i].m_plane[0], m_faces[i].m_plane[1], m_faces[i].m_plane[2]);
204  const btScalar dist = btFabs(m_localCenter.dot(Normal) + m_faces[i].m_plane[3]);
205  if(dist<m_radius)
206  m_radius = dist;
207  }
208 
209 
210  btScalar MinX = FLT_MAX;
211  btScalar MinY = FLT_MAX;
212  btScalar MinZ = FLT_MAX;
213  btScalar MaxX = -FLT_MAX;
214  btScalar MaxY = -FLT_MAX;
215  btScalar MaxZ = -FLT_MAX;
216  for(int i=0; i<m_vertices.size(); i++)
217  {
218  const btVector3& pt = m_vertices[i];
219  if(pt.x()<MinX) MinX = pt.x();
220  if(pt.x()>MaxX) MaxX = pt.x();
221  if(pt.y()<MinY) MinY = pt.y();
222  if(pt.y()>MaxY) MaxY = pt.y();
223  if(pt.z()<MinZ) MinZ = pt.z();
224  if(pt.z()>MaxZ) MaxZ = pt.z();
225  }
226  mC.setValue(MaxX+MinX, MaxY+MinY, MaxZ+MinZ);
227  mE.setValue(MaxX-MinX, MaxY-MinY, MaxZ-MinZ);
228 
229 
230 
231 // const btScalar r = m_radius / sqrtf(2.0f);
232  const btScalar r = m_radius / sqrtf(3.0f);
233  const int LargestExtent = mE.maxAxis();
234  const btScalar Step = (mE[LargestExtent]*0.5f - r)/1024.0f;
235  m_extents[0] = m_extents[1] = m_extents[2] = r;
236  m_extents[LargestExtent] = mE[LargestExtent]*0.5f;
237  bool FoundBox = false;
238  for(int j=0;j<1024;j++)
239  {
240  if(testContainment())
241  {
242  FoundBox = true;
243  break;
244  }
245 
246  m_extents[LargestExtent] -= Step;
247  }
248  if(!FoundBox)
249  {
250  m_extents[0] = m_extents[1] = m_extents[2] = r;
251  }
252  else
253  {
254  // Refine the box
255  const btScalar Step = (m_radius - r)/1024.0f;
256  const int e0 = (1<<LargestExtent) & 3;
257  const int e1 = (1<<e0) & 3;
258 
259  for(int j=0;j<1024;j++)
260  {
261  const btScalar Saved0 = m_extents[e0];
262  const btScalar Saved1 = m_extents[e1];
263  m_extents[e0] += Step;
264  m_extents[e1] += Step;
265 
266  if(!testContainment())
267  {
268  m_extents[e0] = Saved0;
269  m_extents[e1] = Saved1;
270  break;
271  }
272  }
273  }
274  }
275 #endif
276 }
277 
278 void btConvexPolyhedron::project(const btTransform& trans, const btVector3& dir, btScalar& minProj, btScalar& maxProj, btVector3& witnesPtMin,btVector3& witnesPtMax) const
279 {
280  minProj = FLT_MAX;
281  maxProj = -FLT_MAX;
282  int numVerts = m_vertices.size();
283  for(int i=0;i<numVerts;i++)
284  {
285  btVector3 pt = trans * m_vertices[i];
286  btScalar dp = pt.dot(dir);
287  if(dp < minProj)
288  {
289  minProj = dp;
290  witnesPtMin = pt;
291  }
292  if(dp > maxProj)
293  {
294  maxProj = dp;
295  witnesPtMax = pt;
296  }
297  }
298  if(minProj>maxProj)
299  {
300  btSwap(minProj,maxProj);
301  btSwap(witnesPtMin,witnesPtMax);
302  }
303 }
btAlignedObjectArray< btVector3 > m_vertices
btScalar length(const btQuaternion &q)
Return the length of a quaternion.
Definition: btQuaternion.h:886
void push_back(const T &_Val)
void setValue(const btScalar &_x, const btScalar &_y, const btScalar &_z)
Definition: btVector3.h:652
bool equals(const btInternalVertexPair &other) const
const Value * find(const Key &key) const
Definition: btHashMap.h:434
#define btAssert(x)
Definition: btScalar.h:131
btAlignedObjectArray< btVector3 > m_uniqueEdges
bool IsAlmostZero(const btVector3 &v)
The btHashMap template class implements a generic and lightweight hashmap.
Definition: btHashMap.h:225
btVector3 & normalize()
Normalize this vector x^2 + y^2 + z^2 = 1.
Definition: btVector3.h:309
btInternalVertexPair(short int v0, short int v1)
void project(const btTransform &trans, const btVector3 &dir, btScalar &minProj, btScalar &maxProj, btVector3 &witnesPtMin, btVector3 &witnesPtMax) const
bool testContainment() const
const btScalar & x() const
Return the x value.
Definition: btVector3.h:587
btAlignedObjectArray< btFace > m_faces
void btSwap(T &a, T &b)
Definition: btScalar.h:621
btScalar dot(const btVector3 &v) const
Return the dot product.
Definition: btVector3.h:235
btConvexPolyhedron()
This file was written by Erwin Coumans Separating axis rest based on work from Pierre Terdiman...
const btScalar & y() const
Return the y value.
Definition: btVector3.h:589
const btScalar & z() const
Return the z value.
Definition: btVector3.h:591
void insert(const Key &key, const Value &value)
Definition: btHashMap.h:274
btVector3 can be used to represent 3D points and vectors.
Definition: btVector3.h:83
int size() const
return the number of elements in the array
The btTransform class supports rigid transforms with only translation and rotation and no scaling/she...
Definition: btTransform.h:34
void resize(int newsize, const T &fillData=T())
int maxAxis() const
Return the axis with the largest value Note return values are 0,1,2 for x, y, or z.
Definition: btVector3.h:487
float btScalar
The btScalar type abstracts floating point numbers, to easily switch between double and single floati...
Definition: btScalar.h:292
btScalar btFabs(btScalar x)
Definition: btScalar.h:475