Bullet Collision Detection & Physics Library: btGeometryUtil.cpp Source File

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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
33 bool btGeometryUtil::isPointInsidePlanes(const btAlignedObjectArray<btVector3>& planeEquations, const btVector3& point, btScalar margin)
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
50 bool btGeometryUtil::areVerticesBehindPlane(const btVector3& planeNormal, const btAlignedObjectArray<btVector3>& vertices, btScalar margin)
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
81 void btGeometryUtil::getPlaneEquationsFromVertices(btAlignedObjectArray<btVector3>& vertices, btAlignedObjectArray<btVector3>& planeEquationsOut )
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
129 void btGeometryUtil::getVerticesFromPlaneEquations(const btAlignedObjectArray<btVector3>& planeEquations , btAlignedObjectArray<btVector3>& verticesOut )
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
btGeometryUtil::areVerticesBehindPlane
static bool areVerticesBehindPlane(const btVector3 &planeNormal, const btAlignedObjectArray< btVector3 > &vertices, btScalar margin)
Definition: btGeometryUtil.cpp:50
btAlignedObjectArray::push_back
void push_back(const T &_Val)
Definition: btAlignedObjectArray.h:276
notExist
bool notExist(const btVector3 &planeEquation, const btAlignedObjectArray< btVector3 > &planeEquations)
Definition: btGeometryUtil.cpp:67
btAlignedObjectArray< btVector3 >
btBulletMathProbe
void btBulletMathProbe()
Definition: btGeometryUtil.cpp:29
btGeometryUtil.h
btVector3::dot
btScalar dot(const btVector3 &v) const
Return the dot product.
Definition: btVector3.h:235
btVector3::normalize
btVector3 & normalize()
Normalize this vector x^2 + y^2 + z^2 = 1.
Definition: btVector3.h:297
btAlignedObjectArray::size
int size() const
return the number of elements in the array
Definition: btAlignedObjectArray.h:149
btVector3::cross
btVector3 cross(const btVector3 &v) const
Return the cross product between this and another vector.
Definition: btVector3.h:377
btGeometryUtil::getPlaneEquationsFromVertices
static void getPlaneEquationsFromVertices(btAlignedObjectArray< btVector3 > &vertices, btAlignedObjectArray< btVector3 > &planeEquationsOut)
Definition: btGeometryUtil.cpp:81
btVector3
btVector3 can be used to represent 3D points and vectors.
Definition: btVector3.h:83
btVector3::length2
btScalar length2() const
Return the length of the vector squared.
Definition: btVector3.h:257
btGeometryUtil::isPointInsidePlanes
static bool isPointInsidePlanes(const btAlignedObjectArray< btVector3 > &planeEquations, const btVector3 &point, btScalar margin)
Definition: btGeometryUtil.cpp:33
btGeometryUtil::getVerticesFromPlaneEquations
static void getVerticesFromPlaneEquations(const btAlignedObjectArray< btVector3 > &planeEquations, btAlignedObjectArray< btVector3 > &verticesOut)
Definition: btGeometryUtil.cpp:129
btScalar
float btScalar
The btScalar type abstracts floating point numbers, to easily switch between double and single floati...
Definition: btScalar.h:278
btFabs
btScalar btFabs(btScalar x)
Definition: btScalar.h:449