Bullet Collision Detection & Physics Library
btHinge2Constraint.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.
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:
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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.
14 */
15 
16 #include "btHinge2Constraint.h"
19 
20 // constructor
21 // anchor, axis1 and axis2 are in world coordinate system
22 // axis1 must be orthogonal to axis2
24  : btGeneric6DofSpring2Constraint(rbA, rbB, btTransform::getIdentity(), btTransform::getIdentity(), RO_XYZ),
25  m_anchor(anchor),
26  m_axis1(axis1),
27  m_axis2(axis2)
28 {
29  // build frame basis
30  // 6DOF constraint uses Euler angles and to define limits
31  // it is assumed that rotational order is :
32  // Z - first, allowed limits are (-PI,PI);
33  // new position of Y - second (allowed limits are (-PI/2 + epsilon, PI/2 - epsilon), where epsilon is a small positive number
34  // used to prevent constraint from instability on poles;
35  // new position of X, allowed limits are (-PI,PI);
36  // So to simulate ODE Universal joint we should use parent axis as Z, child axis as Y and limit all other DOFs
37  // Build the frame in world coordinate system first
38  btVector3 zAxis = axis1.normalize();
39  btVector3 xAxis = axis2.normalize();
40  btVector3 yAxis = zAxis.cross(xAxis); // we want right coordinate system
41  btTransform frameInW;
42  frameInW.setIdentity();
43  frameInW.getBasis().setValue(xAxis[0], yAxis[0], zAxis[0],
44  xAxis[1], yAxis[1], zAxis[1],
45  xAxis[2], yAxis[2], zAxis[2]);
46  frameInW.setOrigin(anchor);
47  // now get constraint frame in local coordinate systems
48  m_frameInA = rbA.getCenterOfMassTransform().inverse() * frameInW;
49  m_frameInB = rbB.getCenterOfMassTransform().inverse() * frameInW;
50  // sei limits
51  setLinearLowerLimit(btVector3(0.f, 0.f, -1.f));
52  setLinearUpperLimit(btVector3(0.f, 0.f, 1.f));
53  // like front wheels of a car
54  setAngularLowerLimit(btVector3(1.f, 0.f, -SIMD_HALF_PI * 0.5f));
55  setAngularUpperLimit(btVector3(-1.f, 0.f, SIMD_HALF_PI * 0.5f));
56  // enable suspension
57  enableSpring(2, true);
58  setStiffness(2, SIMD_PI * SIMD_PI * 4.f);
59  setDamping(2, 0.01f);
61 }
void setOrigin(const btVector3 &origin)
Set the translational element.
Definition: btTransform.h:146
const btTransform & getCenterOfMassTransform() const
Definition: btRigidBody.h:349
void setIdentity()
Set this transformation to the identity.
Definition: btTransform.h:166
#define SIMD_HALF_PI
Definition: btScalar.h:508
btVector3 & normalize()
Normalize this vector x^2 + y^2 + z^2 = 1.
Definition: btVector3.h:303
#define SIMD_PI
Definition: btScalar.h:506
btVector3 cross(const btVector3 &v) const
Return the cross product between this and another vector.
Definition: btVector3.h:380
btMatrix3x3 & getBasis()
Return the basis matrix for the rotation.
Definition: btTransform.h:108
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:195
The btRigidBody is the main class for rigid body objects.
Definition: btRigidBody.h:59
void setLinearUpperLimit(const btVector3 &linearUpper)
void setLinearLowerLimit(const btVector3 &linearLower)
void setAngularLowerLimit(const btVector3 &angularLower)
btVector3 can be used to represent 3D points and vectors.
Definition: btVector3.h:80
btHinge2Constraint(btRigidBody &rbA, btRigidBody &rbB, btVector3 &anchor, btVector3 &axis1, btVector3 &axis2)
The btTransform class supports rigid transforms with only translation and rotation and no scaling/she...
Definition: btTransform.h:28
void setStiffness(int index, btScalar stiffness, bool limitIfNeeded=true)
void setAngularUpperLimit(const btVector3 &angularUpper)
void setDamping(int index, btScalar damping, bool limitIfNeeded=true)
btTransform inverse() const
Return the inverse of this transform.
Definition: btTransform.h:182