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

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SphereTriangleDetector.cpp
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1 /*
2 Bullet Continuous Collision Detection and Physics Library
3 Copyright (c) 2003-2006 Erwin Coumans http://continuousphysics.com/Bullet/
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 #include "LinearMath/btScalar.h"
17 #include "SphereTriangleDetector.h"
18 #include "BulletCollision/CollisionShapes/btTriangleShape.h"
19 #include "BulletCollision/CollisionShapes/btSphereShape.h"
20
21
22 SphereTriangleDetector::SphereTriangleDetector(btSphereShape* sphere,btTriangleShape* triangle,btScalar contactBreakingThreshold)
23 :m_sphere(sphere),
24 m_triangle(triangle),
25 m_contactBreakingThreshold(contactBreakingThreshold)
26 {
27
28 }
29
30 void SphereTriangleDetector::getClosestPoints(const ClosestPointInput& input,Result& output,class btIDebugDraw* debugDraw,bool swapResults)
31 {
32
33 (void)debugDraw;
34 const btTransform& transformA = input.m_transformA;
35 const btTransform& transformB = input.m_transformB;
36
37 btVector3 point,normal;
38 btScalar timeOfImpact = btScalar(1.);
39 btScalar depth = btScalar(0.);
40 // output.m_distance = btScalar(BT_LARGE_FLOAT);
41 //move sphere into triangle space
42 btTransform sphereInTr = transformB.inverseTimes(transformA);
43
44 if (collide(sphereInTr.getOrigin(),point,normal,depth,timeOfImpact,m_contactBreakingThreshold))
45 {
46 if (swapResults)
47 {
48 btVector3 normalOnB = transformB.getBasis()*normal;
49 btVector3 normalOnA = -normalOnB;
50 btVector3 pointOnA = transformB*point+normalOnB*depth;
51 output.addContactPoint(normalOnA,pointOnA,depth);
52 } else
53 {
54 output.addContactPoint(transformB.getBasis()*normal,transformB*point,depth);
55 }
56 }
57
58 }
59
60
61
62 // See also geometrictools.com
63 // Basic idea: D = |p - (lo + t0*lv)| where t0 = lv . (p - lo) / lv . lv
64 btScalar SegmentSqrDistance(const btVector3& from, const btVector3& to,const btVector3 &p, btVector3 &nearest);
65
66 btScalar SegmentSqrDistance(const btVector3& from, const btVector3& to,const btVector3 &p, btVector3 &nearest) {
67 btVector3 diff = p - from;
68 btVector3 v = to - from;
69 btScalar t = v.dot(diff);
70
71 if (t > 0) {
72 btScalar dotVV = v.dot(v);
73 if (t < dotVV) {
74 t /= dotVV;
75 diff -= t*v;
76 } else {
77 t = 1;
78 diff -= v;
79 }
80 } else
81 t = 0;
82
83 nearest = from + t*v;
84 return diff.dot(diff);
85 }
86
87 bool SphereTriangleDetector::facecontains(const btVector3 &p,const btVector3* vertices,btVector3& normal) {
88 btVector3 lp(p);
89 btVector3 lnormal(normal);
90
91 return pointInTriangle(vertices, lnormal, &lp);
92 }
93
94 bool SphereTriangleDetector::collide(const btVector3& sphereCenter,btVector3 &point, btVector3& resultNormal, btScalar& depth, btScalar &timeOfImpact, btScalar contactBreakingThreshold)
95 {
96
97 const btVector3* vertices = &m_triangle->getVertexPtr(0);
98
99 btScalar radius = m_sphere->getRadius();
100 btScalar radiusWithThreshold = radius + contactBreakingThreshold;
101
102 btVector3 normal = (vertices[1]-vertices[0]).cross(vertices[2]-vertices[0]);
103 normal.normalize();
104 btVector3 p1ToCentre = sphereCenter - vertices[0];
105 btScalar distanceFromPlane = p1ToCentre.dot(normal);
106
107 if (distanceFromPlane < btScalar(0.))
108 {
109 //triangle facing the other way
110 distanceFromPlane *= btScalar(-1.);
111 normal *= btScalar(-1.);
112 }
113
114 bool isInsideContactPlane = distanceFromPlane < radiusWithThreshold;
115
116 // Check for contact / intersection
117 bool hasContact = false;
118 btVector3 contactPoint;
119 if (isInsideContactPlane) {
120 if (facecontains(sphereCenter,vertices,normal)) {
121 // Inside the contact wedge - touches a point on the shell plane
122 hasContact = true;
123 contactPoint = sphereCenter - normal*distanceFromPlane;
124 } else {
125 // Could be inside one of the contact capsules
126 btScalar contactCapsuleRadiusSqr = radiusWithThreshold*radiusWithThreshold;
127 btVector3 nearestOnEdge;
128 for (int i = 0; i < m_triangle->getNumEdges(); i++) {
129
130 btVector3 pa;
131 btVector3 pb;
132
133 m_triangle->getEdge(i,pa,pb);
134
135 btScalar distanceSqr = SegmentSqrDistance(pa,pb,sphereCenter, nearestOnEdge);
136 if (distanceSqr < contactCapsuleRadiusSqr) {
137 // Yep, we're inside a capsule
138 hasContact = true;
139 contactPoint = nearestOnEdge;
140 }
141
142 }
143 }
144 }
145
146 if (hasContact) {
147 btVector3 contactToCentre = sphereCenter - contactPoint;
148 btScalar distanceSqr = contactToCentre.length2();
149
150 if (distanceSqr < radiusWithThreshold*radiusWithThreshold)
151 {
152 if (distanceSqr>SIMD_EPSILON)
153 {
154 btScalar distance = btSqrt(distanceSqr);
155 resultNormal = contactToCentre;
156 resultNormal.normalize();
157 point = contactPoint;
158 depth = -(radius-distance);
159 } else
160 {
161 resultNormal = normal;
162 point = contactPoint;
163 depth = -radius;
164 }
165 return true;
166 }
167 }
168
169 return false;
170 }
171
172
173 bool SphereTriangleDetector::pointInTriangle(const btVector3 vertices[], const btVector3 &normal, btVector3 *p )
174 {
175 const btVector3* p1 = &vertices[0];
176 const btVector3* p2 = &vertices[1];
177 const btVector3* p3 = &vertices[2];
178
179 btVector3 edge1( *p2 - *p1 );
180 btVector3 edge2( *p3 - *p2 );
181 btVector3 edge3( *p1 - *p3 );
182
183 btVector3 p1_to_p( *p - *p1 );
184 btVector3 p2_to_p( *p - *p2 );
185 btVector3 p3_to_p( *p - *p3 );
186
187 btVector3 edge1_normal( edge1.cross(normal));
188 btVector3 edge2_normal( edge2.cross(normal));
189 btVector3 edge3_normal( edge3.cross(normal));
190
191 btScalar r1, r2, r3;
192 r1 = edge1_normal.dot( p1_to_p );
193 r2 = edge2_normal.dot( p2_to_p );
194 r3 = edge3_normal.dot( p3_to_p );
195 if ( ( r1 > 0 && r2 > 0 && r3 > 0 ) ||
196 ( r1 <= 0 && r2 <= 0 && r3 <= 0 ) )
197 return true;
198 return false;
199
200 }
SIMD_EPSILON
#define SIMD_EPSILON
Definition: btScalar.h:494
SphereTriangleDetector::m_contactBreakingThreshold
btScalar m_contactBreakingThreshold
Definition: SphereTriangleDetector.h:47
btDiscreteCollisionDetectorInterface::Result
Definition: btDiscreteCollisionDetectorInterface.h:31
SphereTriangleDetector.h
btSqrt
btScalar btSqrt(btScalar y)
Definition: btScalar.h:418
SphereTriangleDetector::m_triangle
btTriangleShape * m_triangle
Definition: SphereTriangleDetector.h:46
btSphereShape
The btSphereShape implements an implicit sphere, centered around a local origin with radius...
Definition: btSphereShape.h:22
btTriangleShape.h
btTriangleShape
Definition: btTriangleShape.h:22
btDiscreteCollisionDetectorInterface::ClosestPointInput::m_transformA
btTransform m_transformA
Definition: btDiscreteCollisionDetectorInterface.h:49
btVector3::dot
btScalar dot(const btVector3 &v) const
Return the dot product.
Definition: btVector3.h:235
btTransform::inverseTimes
btTransform inverseTimes(const btTransform &t) const
Return the inverse of this transform times the other transform.
Definition: btTransform.h:230
btVector3::normalize
btVector3 & normalize()
Normalize this vector x^2 + y^2 + z^2 = 1.
Definition: btVector3.h:297
btDiscreteCollisionDetectorInterface::ClosestPointInput::m_transformB
btTransform m_transformB
Definition: btDiscreteCollisionDetectorInterface.h:50
SphereTriangleDetector::facecontains
bool facecontains(const btVector3 &p, const btVector3 *vertices, btVector3 &normal)
Definition: SphereTriangleDetector.cpp:87
SphereTriangleDetector::getClosestPoints
virtual void getClosestPoints(const ClosestPointInput &input, Result &output, class btIDebugDraw *debugDraw, bool swapResults=false)
Definition: SphereTriangleDetector.cpp:30
btTransform::getOrigin
btVector3 & getOrigin()
Return the origin vector translation.
Definition: btTransform.h:117
btTriangleShape::getVertexPtr
btVector3 & getVertexPtr(int index)
Definition: btTriangleShape.h:37
output
#define output
SphereTriangleDetector::collide
bool collide(const btVector3 &sphereCenter, btVector3 &point, btVector3 &resultNormal, btScalar &depth, btScalar &timeOfImpact, btScalar contactBreakingThreshold)
Definition: SphereTriangleDetector.cpp:94
btVector3::cross
btVector3 cross(const btVector3 &v) const
Return the cross product between this and another vector.
Definition: btVector3.h:377
SphereTriangleDetector::SphereTriangleDetector
SphereTriangleDetector(btSphereShape *sphere, btTriangleShape *triangle, btScalar contactBreakingThreshold)
Definition: SphereTriangleDetector.cpp:22
btTransform::getBasis
btMatrix3x3 & getBasis()
Return the basis matrix for the rotation.
Definition: btTransform.h:112
btIDebugDraw
The btIDebugDraw interface class allows hooking up a debug renderer to visually debug simulations...
Definition: btIDebugDraw.h:28
SphereTriangleDetector::pointInTriangle
bool pointInTriangle(const btVector3 vertices[], const btVector3 &normal, btVector3 *p)
Definition: SphereTriangleDetector.cpp:173
btTriangleShape::getNumEdges
virtual int getNumEdges() const
Definition: btTriangleShape.h:51
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
btTransform
The btTransform class supports rigid transforms with only translation and rotation and no scaling/she...
Definition: btTransform.h:34
btDiscreteCollisionDetectorInterface::Result::addContactPoint
virtual void addContactPoint(const btVector3 &normalOnBInWorld, const btVector3 &pointInWorld, btScalar depth)=0
SphereTriangleDetector::m_sphere
btSphereShape * m_sphere
Definition: SphereTriangleDetector.h:45
btTriangleShape::getEdge
virtual void getEdge(int i, btVector3 &pa, btVector3 &pb) const
Definition: btTriangleShape.h:56
btSphereShape::getRadius
btScalar getRadius() const
Definition: btSphereShape.h:47
btDiscreteCollisionDetectorInterface::ClosestPointInput
Definition: btDiscreteCollisionDetectorInterface.h:42
btSphereShape.h
SegmentSqrDistance
btScalar SegmentSqrDistance(const btVector3 &from, const btVector3 &to, const btVector3 &p, btVector3 &nearest)
Definition: SphereTriangleDetector.cpp:66
btScalar
float btScalar
The btScalar type abstracts floating point numbers, to easily switch between double and single floati...
Definition: btScalar.h:278
btScalar.h