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

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 #include "btGeometryUtil.h"
16
17 /*
18 Make sure this dummy function never changes so that it
19 can be used by probes that are checking whether the
20 library is actually installed.
21 */
22 extern "C"
23 {
24 void btBulletMathProbe();
25
26 void btBulletMathProbe() {}
27 }
28
29 bool btGeometryUtil::isPointInsidePlanes(const btAlignedObjectArray<btVector3>& planeEquations, const btVector3& point, btScalar margin)
30 {
31 int numbrushes = planeEquations.size();
32 for (int i = 0; i < numbrushes; i++)
33 {
34 const btVector3& N1 = planeEquations[i];
35 btScalar dist = btScalar(N1.dot(point)) + btScalar(N1[3]) - margin;
36 if (dist > btScalar(0.))
37 {
38 return false;
39 }
40 }
41 return true;
42 }
43
44 bool btGeometryUtil::areVerticesBehindPlane(const btVector3& planeNormal, const btAlignedObjectArray<btVector3>& vertices, btScalar margin)
45 {
46 int numvertices = vertices.size();
47 for (int i = 0; i < numvertices; i++)
48 {
49 const btVector3& N1 = vertices[i];
50 btScalar dist = btScalar(planeNormal.dot(N1)) + btScalar(planeNormal[3]) - margin;
51 if (dist > btScalar(0.))
52 {
53 return false;
54 }
55 }
56 return true;
57 }
58
59 bool notExist(const btVector3& planeEquation, const btAlignedObjectArray<btVector3>& planeEquations);
60
61 bool notExist(const btVector3& planeEquation, const btAlignedObjectArray<btVector3>& planeEquations)
62 {
63 int numbrushes = planeEquations.size();
64 for (int i = 0; i < numbrushes; i++)
65 {
66 const btVector3& N1 = planeEquations[i];
67 if (planeEquation.dot(N1) > btScalar(0.999))
68 {
69 return false;
70 }
71 }
72 return true;
73 }
74
75 void btGeometryUtil::getPlaneEquationsFromVertices(btAlignedObjectArray<btVector3>& vertices, btAlignedObjectArray<btVector3>& planeEquationsOut)
76 {
77 const int numvertices = vertices.size();
78 // brute force:
79 for (int i = 0; i < numvertices; i++)
80 {
81 const btVector3& N1 = vertices[i];
82
83 for (int j = i + 1; j < numvertices; j++)
84 {
85 const btVector3& N2 = vertices[j];
86
87 for (int k = j + 1; k < numvertices; k++)
88 {
89 const btVector3& N3 = vertices[k];
90
91 btVector3 planeEquation, edge0, edge1;
92 edge0 = N2 - N1;
93 edge1 = N3 - N1;
94 btScalar normalSign = btScalar(1.);
95 for (int ww = 0; ww < 2; ww++)
96 {
97 planeEquation = normalSign * edge0.cross(edge1);
98 if (planeEquation.length2() > btScalar(0.0001))
99 {
100 planeEquation.normalize();
101 if (notExist(planeEquation, planeEquationsOut))
102 {
103 planeEquation[3] = -planeEquation.dot(N1);
104
105 //check if inside, and replace supportingVertexOut if needed
106 if (areVerticesBehindPlane(planeEquation, vertices, btScalar(0.01)))
107 {
108 planeEquationsOut.push_back(planeEquation);
109 }
110 }
111 }
112 normalSign = btScalar(-1.);
113 }
114 }
115 }
116 }
117 }
118
119 void btGeometryUtil::getVerticesFromPlaneEquations(const btAlignedObjectArray<btVector3>& planeEquations, btAlignedObjectArray<btVector3>& verticesOut)
120 {
121 const int numbrushes = planeEquations.size();
122 // brute force:
123 for (int i = 0; i < numbrushes; i++)
124 {
125 const btVector3& N1 = planeEquations[i];
126
127 for (int j = i + 1; j < numbrushes; j++)
128 {
129 const btVector3& N2 = planeEquations[j];
130
131 for (int k = j + 1; k < numbrushes; k++)
132 {
133 const btVector3& N3 = planeEquations[k];
134
135 btVector3 n2n3;
136 n2n3 = N2.cross(N3);
137 btVector3 n3n1;
138 n3n1 = N3.cross(N1);
139 btVector3 n1n2;
140 n1n2 = N1.cross(N2);
141
142 if ((n2n3.length2() > btScalar(0.0001)) &&
143 (n3n1.length2() > btScalar(0.0001)) &&
144 (n1n2.length2() > btScalar(0.0001)))
145 {
146 //point P out of 3 plane equations:
147
148 // d1 ( N2 * N3 ) + d2 ( N3 * N1 ) + d3 ( N1 * N2 )
149 //P = -------------------------------------------------------------------------
150 // N1 . ( N2 * N3 )
151
152 btScalar quotient = (N1.dot(n2n3));
153 if (btFabs(quotient) > btScalar(0.000001))
154 {
155 quotient = btScalar(-1.) / quotient;
156 n2n3 *= N1[3];
157 n3n1 *= N2[3];
158 n1n2 *= N3[3];
159 btVector3 potentialVertex = n2n3;
160 potentialVertex += n3n1;
161 potentialVertex += n1n2;
162 potentialVertex *= quotient;
163
164 //check if inside, and replace supportingVertexOut if needed
165 if (isPointInsidePlanes(planeEquations, potentialVertex, btScalar(0.01)))
166 {
167 verticesOut.push_back(potentialVertex);
168 }
169 }
170 }
171 }
172 }
173 }
174 }
btGeometryUtil::areVerticesBehindPlane
static bool areVerticesBehindPlane(const btVector3 &planeNormal, const btAlignedObjectArray< btVector3 > &vertices, btScalar margin)
Definition: btGeometryUtil.cpp:44
btAlignedObjectArray::push_back
void push_back(const T &_Val)
Definition: btAlignedObjectArray.h:264
notExist
bool notExist(const btVector3 &planeEquation, const btAlignedObjectArray< btVector3 > &planeEquations)
Definition: btGeometryUtil.cpp:61
btAlignedObjectArray< btVector3 >
btBulletMathProbe
void btBulletMathProbe()
Definition: btGeometryUtil.cpp:26
btVector3::length2
btScalar length2() const
Return the length of the vector squared.
Definition: btVector3.h:251
btGeometryUtil.h
btVector3::normalize
btVector3 & normalize()
Normalize this vector x^2 + y^2 + z^2 = 1.
Definition: btVector3.h:303
btVector3::cross
btVector3 cross(const btVector3 &v) const
Return the cross product between this and another vector.
Definition: btVector3.h:380
btVector3::dot
btScalar dot(const btVector3 &v) const
Return the dot product.
Definition: btVector3.h:229
btGeometryUtil::getPlaneEquationsFromVertices
static void getPlaneEquationsFromVertices(btAlignedObjectArray< btVector3 > &vertices, btAlignedObjectArray< btVector3 > &planeEquationsOut)
Definition: btGeometryUtil.cpp:75
btVector3
btVector3 can be used to represent 3D points and vectors.
Definition: btVector3.h:80
btAlignedObjectArray::size
int size() const
return the number of elements in the array
Definition: btAlignedObjectArray.h:149
btGeometryUtil::isPointInsidePlanes
static bool isPointInsidePlanes(const btAlignedObjectArray< btVector3 > &planeEquations, const btVector3 &point, btScalar margin)
Definition: btGeometryUtil.cpp:29
btGeometryUtil::getVerticesFromPlaneEquations
static void getVerticesFromPlaneEquations(const btAlignedObjectArray< btVector3 > &planeEquations, btAlignedObjectArray< btVector3 > &verticesOut)
Definition: btGeometryUtil.cpp:119
btScalar
float btScalar
The btScalar type abstracts floating point numbers, to easily switch between double and single floati...
Definition: btScalar.h:294
btFabs
btScalar btFabs(btScalar x)
Definition: btScalar.h:477