forked from LeenkxTeam/LNXSDK
		
	
		
			
				
	
	
		
			67 lines
		
	
	
		
			3.0 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			67 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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