/* | |
Bullet Continuous Collision Detection and Physics Library, http://bulletphysics.org | |
Copyright (C) 2006, 2007 Sony Computer Entertainment Inc. | |
This software is provided 'as-is', without any express or implied warranty. | |
In no event will the authors be held liable for any damages arising from the use of this software. | |
Permission is granted to anyone to use this software for any purpose, | |
including commercial applications, and to alter it and redistribute it freely, | |
subject to the following restrictions: | |
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. | |
2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software. | |
3. This notice may not be removed or altered from any source distribution. | |
*/ | |
#include "BulletDynamics/ConstraintSolver/btHinge2Constraint.h" | |
#include "BulletDynamics/Dynamics/btRigidBody.h" | |
#include "LinearMath/btTransformUtil.h" | |
// constructor | |
// anchor, axis1 and axis2 are in world coordinate system | |
// axis1 must be orthogonal to axis2 | |
btHinge2Constraint::btHinge2Constraint(btRigidBody& rbA, btRigidBody& rbB, btVector3& anchor, btVector3& axis1, btVector3& axis2) | |
: btGeneric6DofSpringConstraint(rbA, rbB, btTransform::getIdentity(), btTransform::getIdentity(), true), | |
m_anchor(anchor), | |
m_axis1(axis1), | |
m_axis2(axis2) | |
{ | |
// build frame basis | |
// 6DOF constraint uses Euler angles and to define limits | |
// it is assumed that rotational order is : | |
// Z - first, allowed limits are (-PI,PI); | |
// new position of Y - second (allowed limits are (-PI/2 + epsilon, PI/2 - epsilon), where epsilon is a small positive number | |
// used to prevent constraint from instability on poles; | |
// new position of X, allowed limits are (-PI,PI); | |
// So to simulate ODE Universal joint we should use parent axis as Z, child axis as Y and limit all other DOFs | |
// Build the frame in world coordinate system first | |
btVector3 zAxis = axis1.normalize(); | |
btVector3 xAxis = axis2.normalize(); | |
btVector3 yAxis = zAxis.cross(xAxis); // we want right coordinate system | |
btTransform frameInW; | |
frameInW.setIdentity(); | |
frameInW.getBasis().setValue( xAxis[0], yAxis[0], zAxis[0], | |
xAxis[1], yAxis[1], zAxis[1], | |
xAxis[2], yAxis[2], zAxis[2]); | |
frameInW.setOrigin(anchor); | |
// now get constraint frame in local coordinate systems | |
m_frameInA = rbA.getCenterOfMassTransform().inverse() * frameInW; | |
m_frameInB = rbB.getCenterOfMassTransform().inverse() * frameInW; | |
// sei limits | |
setLinearLowerLimit(btVector3(0.f, 0.f, -1.f)); | |
setLinearUpperLimit(btVector3(0.f, 0.f, 1.f)); | |
// like front wheels of a car | |
setAngularLowerLimit(btVector3(1.f, 0.f, -SIMD_HALF_PI * 0.5f)); | |
setAngularUpperLimit(btVector3(-1.f, 0.f, SIMD_HALF_PI * 0.5f)); | |
// enable suspension | |
enableSpring(2, true); | |
setStiffness(2, SIMD_PI * SIMD_PI * 4.f); // period 1 sec for 1 kilogramm weel :-) | |
setDamping(2, 0.01f); | |
setEquilibriumPoint(); | |
} | |