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

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btUniversalConstraint.cpp
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1/*
2Bullet Continuous Collision Detection and Physics Library, http://bulletphysics.org
3Copyright (C) 2006, 2007 Sony Computer Entertainment Inc.
4
5This software is provided 'as-is', without any express or implied warranty.
6In no event will the authors be held liable for any damages arising from the use of this software.
7Permission is granted to anyone to use this software for any purpose,
8including commercial applications, and to alter it and redistribute it freely,
9subject to the following restrictions:
10
111. 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.
122. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
133. This notice may not be removed or altered from any source distribution.
14*/
15
16#include "btUniversalConstraint.h"
17#include "BulletDynamics/Dynamics/btRigidBody.h"
18#include "LinearMath/btTransformUtil.h"
19
20#define UNIV_EPS btScalar(0.01f)
21
22// constructor
23// anchor, axis1 and axis2 are in world coordinate system
24// axis1 must be orthogonal to axis2
25btUniversalConstraint::btUniversalConstraint(btRigidBody& rbA, btRigidBody& rbB, const btVector3& anchor, const btVector3& axis1, const btVector3& axis2)
26 : btGeneric6DofConstraint(rbA, rbB, btTransform::getIdentity(), btTransform::getIdentity(), true),
27 m_anchor(anchor),
28 m_axis1(axis1),
29 m_axis2(axis2)
30{
31 // build frame basis
32 // 6DOF constraint uses Euler angles and to define limits
33 // it is assumed that rotational order is :
34 // Z - first, allowed limits are (-PI,PI);
35 // new position of Y - second (allowed limits are (-PI/2 + epsilon, PI/2 - epsilon), where epsilon is a small positive number
36 // used to prevent constraint from instability on poles;
37 // new position of X, allowed limits are (-PI,PI);
38 // So to simulate ODE Universal joint we should use parent axis as Z, child axis as Y and limit all other DOFs
39 // Build the frame in world coordinate system first
40 btVector3 zAxis = m_axis1.normalize();
41 btVector3 yAxis = m_axis2.normalize();
42 btVector3 xAxis = yAxis.cross(zAxis); // we want right coordinate system
43 btTransform frameInW;
44 frameInW.setIdentity();
45 frameInW.getBasis().setValue(xAxis[0], yAxis[0], zAxis[0],
46 xAxis[1], yAxis[1], zAxis[1],
47 xAxis[2], yAxis[2], zAxis[2]);
48 frameInW.setOrigin(anchor);
49 // now get constraint frame in local coordinate systems
50 m_frameInA = rbA.getCenterOfMassTransform().inverse() * frameInW;
51 m_frameInB = rbB.getCenterOfMassTransform().inverse() * frameInW;
52 // sei limits
53 setLinearLowerLimit(btVector3(0., 0., 0.));
54 setLinearUpperLimit(btVector3(0., 0., 0.));
55 setAngularLowerLimit(btVector3(0.f, -SIMD_HALF_PI + UNIV_EPS, -SIMD_PI + UNIV_EPS));
56 setAngularUpperLimit(btVector3(0.f, SIMD_HALF_PI - UNIV_EPS, SIMD_PI - UNIV_EPS));
57}
58
59 void btUniversalConstraint::setAxis(const btVector3& axis1, const btVector3& axis2)
60{
61 m_axis1 = axis1;
62 m_axis2 = axis2;
63
64 btVector3 zAxis = axis1.normalized();
65 btVector3 yAxis = axis2.normalized();
66 btVector3 xAxis = yAxis.cross(zAxis); // we want right coordinate system
67
68 btTransform frameInW;
69 frameInW.setIdentity();
70 frameInW.getBasis().setValue(xAxis[0], yAxis[0], zAxis[0],
71 xAxis[1], yAxis[1], zAxis[1],
72 xAxis[2], yAxis[2], zAxis[2]);
73 frameInW.setOrigin(m_anchor);
74
75 // now get constraint frame in local coordinate systems
76 m_frameInA = m_rbA.getCenterOfMassTransform().inverse() * frameInW;
77 m_frameInB = m_rbB.getCenterOfMassTransform().inverse() * frameInW;
78
79 calculateTransforms();
80}
inverse
btQuaternion inverse(const btQuaternion &q)
Return the inverse of a quaternion.
Definition btQuaternion.h:909
btRigidBody.h
SIMD_PI
#define SIMD_PI
Definition btScalar.h:526
SIMD_HALF_PI
#define SIMD_HALF_PI
Definition btScalar.h:528
btTransformUtil.h
UNIV_EPS
#define UNIV_EPS
Definition btUniversalConstraint.cpp:20
btUniversalConstraint.h
btGeneric6DofConstraint
btGeneric6DofConstraint between two rigidbodies each with a pivotpoint that descibes the axis locatio...
Definition btGeneric6DofConstraint.h:268
btGeneric6DofConstraint::m_frameInA
btTransform m_frameInA
relative_frames
Definition btGeneric6DofConstraint.h:272
btGeneric6DofConstraint::setLinearLowerLimit
void setLinearLowerLimit(const btVector3 &linearLower)
Definition btGeneric6DofConstraint.h:433
btGeneric6DofConstraint::setAngularLowerLimit
void setAngularLowerLimit(const btVector3 &angularLower)
Definition btGeneric6DofConstraint.h:453
btGeneric6DofConstraint::m_frameInB
btTransform m_frameInB
the constraint space w.r.t body B
Definition btGeneric6DofConstraint.h:273
btGeneric6DofConstraint::calculateTransforms
void calculateTransforms()
Definition btGeneric6DofConstraint.cpp:336
btGeneric6DofConstraint::setAngularUpperLimit
void setAngularUpperLimit(const btVector3 &angularUpper)
Definition btGeneric6DofConstraint.h:465
btGeneric6DofConstraint::setLinearUpperLimit
void setLinearUpperLimit(const btVector3 &linearUpper)
Definition btGeneric6DofConstraint.h:443
btMatrix3x3::setValue
void setValue(const btScalar &xx, const btScalar &xy, const btScalar &xz, const btScalar &yx, const btScalar &yy, const btScalar &yz, const btScalar &zx, const btScalar &zy, const btScalar &zz)
Set the values of the matrix explicitly (row major)
Definition btMatrix3x3.h:204
btRigidBody
The btRigidBody is the main class for rigid body objects.
Definition btRigidBody.h:60
btRigidBody::getCenterOfMassTransform
const btTransform & getCenterOfMassTransform() const
Definition btRigidBody.h:429
btTransform
The btTransform class supports rigid transforms with only translation and rotation and no scaling/she...
Definition btTransform.h:30
btTransform::inverse
btTransform inverse() const
Return the inverse of this transform.
Definition btTransform.h:183
btTransform::getBasis
btMatrix3x3 & getBasis()
Return the basis matrix for the rotation.
Definition btTransform.h:109
btTransform::setIdentity
void setIdentity()
Set this transformation to the identity.
Definition btTransform.h:167
btTransform::setOrigin
void setOrigin(const btVector3 &origin)
Set the translational element.
Definition btTransform.h:147
btTypedConstraint::m_rbA
btRigidBody & m_rbA
Definition btTypedConstraint.h:97
btTypedConstraint::m_rbB
btRigidBody & m_rbB
Definition btTypedConstraint.h:98
btUniversalConstraint::setAxis
void setAxis(const btVector3 &axis1, const btVector3 &axis2)
Definition btUniversalConstraint.cpp:59
btUniversalConstraint::m_axis2
btVector3 m_axis2
Definition btUniversalConstraint.h:36
btUniversalConstraint::btUniversalConstraint
btUniversalConstraint(btRigidBody &rbA, btRigidBody &rbB, const btVector3 &anchor, const btVector3 &axis1, const btVector3 &axis2)
Definition btUniversalConstraint.cpp:25
btUniversalConstraint::m_anchor
btVector3 m_anchor
Definition btUniversalConstraint.h:34
btUniversalConstraint::m_axis1
btVector3 m_axis1
Definition btUniversalConstraint.h:35
btVector3
btVector3 can be used to represent 3D points and vectors.
Definition btVector3.h:82
btVector3::cross
btVector3 cross(const btVector3 &v) const
Return the cross product between this and another vector.
Definition btVector3.h:380
btVector3::normalized
btVector3 normalized() const
Return a normalized version of this vector.
Definition btVector3.h:949
btVector3::normalize
btVector3 & normalize()
Normalize this vector x^2 + y^2 + z^2 = 1.
Definition btVector3.h:303