62 lines
3.0 KiB
C++
62 lines
3.0 KiB
C++
/*
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Bullet Continuous Collision Detection and Physics Library, http://bulletphysics.org
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Copyright (C) 2006, 2007 Sony Computer Entertainment Inc.
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This software is provided 'as-is', without any express or implied warranty.
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In no event will the authors be held liable for any damages arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it freely,
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subject to the following restrictions:
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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.
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2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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*/
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#include "btHinge2Constraint.h"
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#include "BulletDynamics/Dynamics/btRigidBody.h"
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#include "LinearMath/btTransformUtil.h"
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// constructor
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// anchor, axis1 and axis2 are in world coordinate system
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// axis1 must be orthogonal to axis2
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btHinge2Constraint::btHinge2Constraint(btRigidBody& rbA, btRigidBody& rbB, btVector3& anchor, btVector3& axis1, btVector3& axis2)
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: btGeneric6DofSpring2Constraint(rbA, rbB, btTransform::getIdentity(), btTransform::getIdentity(), RO_XYZ),
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m_anchor(anchor),
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m_axis1(axis1),
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m_axis2(axis2)
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{
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// build frame basis
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// 6DOF constraint uses Euler angles and to define limits
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// it is assumed that rotational order is :
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// Z - first, allowed limits are (-PI,PI);
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// new position of Y - second (allowed limits are (-PI/2 + epsilon, PI/2 - epsilon), where epsilon is a small positive number
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// used to prevent constraint from instability on poles;
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// new position of X, allowed limits are (-PI,PI);
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// So to simulate ODE Universal joint we should use parent axis as Z, child axis as Y and limit all other DOFs
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// Build the frame in world coordinate system first
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btVector3 zAxis = axis1.normalize();
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btVector3 xAxis = axis2.normalize();
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btVector3 yAxis = zAxis.cross(xAxis); // we want right coordinate system
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btTransform frameInW;
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frameInW.setIdentity();
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frameInW.getBasis().setValue(xAxis[0], yAxis[0], zAxis[0],
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xAxis[1], yAxis[1], zAxis[1],
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xAxis[2], yAxis[2], zAxis[2]);
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frameInW.setOrigin(anchor);
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// now get constraint frame in local coordinate systems
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m_frameInA = rbA.getCenterOfMassTransform().inverse() * frameInW;
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m_frameInB = rbB.getCenterOfMassTransform().inverse() * frameInW;
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// sei limits
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setLinearLowerLimit(btVector3(0.f, 0.f, -1.f));
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setLinearUpperLimit(btVector3(0.f, 0.f, 1.f));
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// like front wheels of a car
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setAngularLowerLimit(btVector3(1.f, 0.f, -SIMD_HALF_PI * 0.5f));
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setAngularUpperLimit(btVector3(-1.f, 0.f, SIMD_HALF_PI * 0.5f));
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// enable suspension
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enableSpring(2, true);
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setStiffness(2, SIMD_PI * SIMD_PI * 4.f);
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setDamping(2, 0.01f);
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setEquilibriumPoint();
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}
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