Bullet Collision Detection & Physics Library
btGeometryUtil.cpp
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1 /*
2 Copyright (c) 2003-2006 Gino van den Bergen / Erwin Coumans http://continuousphysics.com/Bullet/
3 
4 This software is provided 'as-is', without any express or implied warranty.
5 In no event will the authors be held liable for any damages arising from the use of this software.
6 Permission is granted to anyone to use this software for any purpose,
7 including commercial applications, and to alter it and redistribute it freely,
8 subject to the following restrictions:
9 
10 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.
11 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
12 3. This notice may not be removed or altered from any source distribution.
13 */
14 
15 
16 
17 #include "btGeometryUtil.h"
18 
19 
20 /*
21  Make sure this dummy function never changes so that it
22  can be used by probes that are checking whether the
23  library is actually installed.
24 */
25 extern "C"
26 {
27  void btBulletMathProbe ();
28 
29  void btBulletMathProbe () {}
30 }
31 
32 
34 {
35  int numbrushes = planeEquations.size();
36  for (int i=0;i<numbrushes;i++)
37  {
38  const btVector3& N1 = planeEquations[i];
39  btScalar dist = btScalar(N1.dot(point))+btScalar(N1[3])-margin;
40  if (dist>btScalar(0.))
41  {
42  return false;
43  }
44  }
45  return true;
46 
47 }
48 
49 
51 {
52  int numvertices = vertices.size();
53  for (int i=0;i<numvertices;i++)
54  {
55  const btVector3& N1 = vertices[i];
56  btScalar dist = btScalar(planeNormal.dot(N1))+btScalar(planeNormal[3])-margin;
57  if (dist>btScalar(0.))
58  {
59  return false;
60  }
61  }
62  return true;
63 }
64 
65 bool notExist(const btVector3& planeEquation,const btAlignedObjectArray<btVector3>& planeEquations);
66 
67 bool notExist(const btVector3& planeEquation,const btAlignedObjectArray<btVector3>& planeEquations)
68 {
69  int numbrushes = planeEquations.size();
70  for (int i=0;i<numbrushes;i++)
71  {
72  const btVector3& N1 = planeEquations[i];
73  if (planeEquation.dot(N1) > btScalar(0.999))
74  {
75  return false;
76  }
77  }
78  return true;
79 }
80 
82 {
83  const int numvertices = vertices.size();
84  // brute force:
85  for (int i=0;i<numvertices;i++)
86  {
87  const btVector3& N1 = vertices[i];
88 
89 
90  for (int j=i+1;j<numvertices;j++)
91  {
92  const btVector3& N2 = vertices[j];
93 
94  for (int k=j+1;k<numvertices;k++)
95  {
96 
97  const btVector3& N3 = vertices[k];
98 
99  btVector3 planeEquation,edge0,edge1;
100  edge0 = N2-N1;
101  edge1 = N3-N1;
102  btScalar normalSign = btScalar(1.);
103  for (int ww=0;ww<2;ww++)
104  {
105  planeEquation = normalSign * edge0.cross(edge1);
106  if (planeEquation.length2() > btScalar(0.0001))
107  {
108  planeEquation.normalize();
109  if (notExist(planeEquation,planeEquationsOut))
110  {
111  planeEquation[3] = -planeEquation.dot(N1);
112 
113  //check if inside, and replace supportingVertexOut if needed
114  if (areVerticesBehindPlane(planeEquation,vertices,btScalar(0.01)))
115  {
116  planeEquationsOut.push_back(planeEquation);
117  }
118  }
119  }
120  normalSign = btScalar(-1.);
121  }
122 
123  }
124  }
125  }
126 
127 }
128 
130 {
131  const int numbrushes = planeEquations.size();
132  // brute force:
133  for (int i=0;i<numbrushes;i++)
134  {
135  const btVector3& N1 = planeEquations[i];
136 
137 
138  for (int j=i+1;j<numbrushes;j++)
139  {
140  const btVector3& N2 = planeEquations[j];
141 
142  for (int k=j+1;k<numbrushes;k++)
143  {
144 
145  const btVector3& N3 = planeEquations[k];
146 
147  btVector3 n2n3; n2n3 = N2.cross(N3);
148  btVector3 n3n1; n3n1 = N3.cross(N1);
149  btVector3 n1n2; n1n2 = N1.cross(N2);
150 
151  if ( ( n2n3.length2() > btScalar(0.0001) ) &&
152  ( n3n1.length2() > btScalar(0.0001) ) &&
153  ( n1n2.length2() > btScalar(0.0001) ) )
154  {
155  //point P out of 3 plane equations:
156 
157  // d1 ( N2 * N3 ) + d2 ( N3 * N1 ) + d3 ( N1 * N2 )
158  //P = -------------------------------------------------------------------------
159  // N1 . ( N2 * N3 )
160 
161 
162  btScalar quotient = (N1.dot(n2n3));
163  if (btFabs(quotient) > btScalar(0.000001))
164  {
165  quotient = btScalar(-1.) / quotient;
166  n2n3 *= N1[3];
167  n3n1 *= N2[3];
168  n1n2 *= N3[3];
169  btVector3 potentialVertex = n2n3;
170  potentialVertex += n3n1;
171  potentialVertex += n1n2;
172  potentialVertex *= quotient;
173 
174  //check if inside, and replace supportingVertexOut if needed
175  if (isPointInsidePlanes(planeEquations,potentialVertex,btScalar(0.01)))
176  {
177  verticesOut.push_back(potentialVertex);
178  }
179  }
180  }
181  }
182  }
183  }
184 }
185 
static bool areVerticesBehindPlane(const btVector3 &planeNormal, const btAlignedObjectArray< btVector3 > &vertices, btScalar margin)
void push_back(const T &_Val)
bool notExist(const btVector3 &planeEquation, const btAlignedObjectArray< btVector3 > &planeEquations)
void btBulletMathProbe()
btScalar dot(const btVector3 &v) const
Return the dot product.
Definition: btVector3.h:235
btVector3 & normalize()
Normalize this vector x^2 + y^2 + z^2 = 1.
Definition: btVector3.h:309
int size() const
return the number of elements in the array
btVector3 cross(const btVector3 &v) const
Return the cross product between this and another vector.
Definition: btVector3.h:389
static void getPlaneEquationsFromVertices(btAlignedObjectArray< btVector3 > &vertices, btAlignedObjectArray< btVector3 > &planeEquationsOut)
btVector3 can be used to represent 3D points and vectors.
Definition: btVector3.h:83
btScalar length2() const
Return the length of the vector squared.
Definition: btVector3.h:257
static bool isPointInsidePlanes(const btAlignedObjectArray< btVector3 > &planeEquations, const btVector3 &point, btScalar margin)
static void getVerticesFromPlaneEquations(const btAlignedObjectArray< btVector3 > &planeEquations, btAlignedObjectArray< btVector3 > &verticesOut)
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