Bullet Collision Detection & Physics Library
btUniversalConstraint.cpp
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1 /*
2 Bullet Continuous Collision Detection and Physics Library, http://bulletphysics.org
3 Copyright (C) 2006, 2007 Sony Computer Entertainment Inc.
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.
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8 including commercial applications, and to alter it and redistribute it freely,
9 subject to the following restrictions:
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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.
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15 
16 
17 
18 #include "btUniversalConstraint.h"
21 
22 
23 
24 #define UNIV_EPS btScalar(0.01f)
25 
26 
27 // constructor
28 // anchor, axis1 and axis2 are in world coordinate system
29 // axis1 must be orthogonal to axis2
31 : btGeneric6DofConstraint(rbA, rbB, btTransform::getIdentity(), btTransform::getIdentity(), true),
32  m_anchor(anchor),
33  m_axis1(axis1),
34  m_axis2(axis2)
35 {
36  // build frame basis
37  // 6DOF constraint uses Euler angles and to define limits
38  // it is assumed that rotational order is :
39  // Z - first, allowed limits are (-PI,PI);
40  // new position of Y - second (allowed limits are (-PI/2 + epsilon, PI/2 - epsilon), where epsilon is a small positive number
41  // used to prevent constraint from instability on poles;
42  // new position of X, allowed limits are (-PI,PI);
43  // So to simulate ODE Universal joint we should use parent axis as Z, child axis as Y and limit all other DOFs
44  // Build the frame in world coordinate system first
45  btVector3 zAxis = m_axis1.normalize();
46  btVector3 yAxis = m_axis2.normalize();
47  btVector3 xAxis = yAxis.cross(zAxis); // we want right coordinate system
48  btTransform frameInW;
49  frameInW.setIdentity();
50  frameInW.getBasis().setValue( xAxis[0], yAxis[0], zAxis[0],
51  xAxis[1], yAxis[1], zAxis[1],
52  xAxis[2], yAxis[2], zAxis[2]);
53  frameInW.setOrigin(anchor);
54  // now get constraint frame in local coordinate systems
55  m_frameInA = rbA.getCenterOfMassTransform().inverse() * frameInW;
56  m_frameInB = rbB.getCenterOfMassTransform().inverse() * frameInW;
57  // sei limits
58  setLinearLowerLimit(btVector3(0., 0., 0.));
59  setLinearUpperLimit(btVector3(0., 0., 0.));
62 }
63 
64 void btUniversalConstraint::setAxis(const btVector3& axis1,const btVector3& axis2)
65 {
66  m_axis1 = axis1;
67  m_axis2 = axis2;
68 
69  btVector3 zAxis = axis1.normalized();
70  btVector3 yAxis = axis2.normalized();
71  btVector3 xAxis = yAxis.cross(zAxis); // we want right coordinate system
72 
73  btTransform frameInW;
74  frameInW.setIdentity();
75  frameInW.getBasis().setValue( xAxis[0], yAxis[0], zAxis[0],
76  xAxis[1], yAxis[1], zAxis[1],
77  xAxis[2], yAxis[2], zAxis[2]);
78  frameInW.setOrigin(m_anchor);
79 
80  // now get constraint frame in local coordinate systems
83 
85 }
86 
87 
void setOrigin(const btVector3 &origin)
Set the translational element.
Definition: btTransform.h:150
#define UNIV_EPS
btGeneric6DofConstraint between two rigidbodies each with a pivotpoint that descibes the axis locatio...
void setIdentity()
Set this transformation to the identity.
Definition: btTransform.h:172
void setAngularUpperLimit(const btVector3 &angularUpper)
#define SIMD_HALF_PI
Definition: btScalar.h:436
void setAxis(const btVector3 &axis1, const btVector3 &axis2)
btVector3 & normalize()
Normalize this vector x^2 + y^2 + z^2 = 1.
Definition: btVector3.h:297
#define SIMD_PI
Definition: btScalar.h:434
const btTransform & getCenterOfMassTransform() const
Definition: btRigidBody.h:353
btVector3 cross(const btVector3 &v) const
Return the cross product between this and another vector.
Definition: btVector3.h:377
btMatrix3x3 & getBasis()
Return the basis matrix for the rotation.
Definition: btTransform.h:112
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:198
The btRigidBody is the main class for rigid body objects.
Definition: btRigidBody.h:59
btTransform inverse() const
Return the inverse of this transform.
Definition: btTransform.h:188
btVector3 can be used to represent 3D points and vectors.
Definition: btVector3.h:83
btTransform m_frameInA
relative_frames
The btTransform class supports rigid transforms with only translation and rotation and no scaling/she...
Definition: btTransform.h:34
btVector3 normalized() const
Return a normalized version of this vector.
Definition: btVector3.h:951
btTransform m_frameInB
the constraint space w.r.t body B
void setLinearLowerLimit(const btVector3 &linearLower)
btUniversalConstraint(btRigidBody &rbA, btRigidBody &rbB, const btVector3 &anchor, const btVector3 &axis1, const btVector3 &axis2)
void setLinearUpperLimit(const btVector3 &linearUpper)
void setAngularLowerLimit(const btVector3 &angularLower)