643 lines
		
	
	
		
			17 KiB
		
	
	
	
		
			C++
		
	
	
	
			
		
		
	
	
			643 lines
		
	
	
		
			17 KiB
		
	
	
	
		
			C++
		
	
	
	
| /*
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| * Copyright (c) 2006-2011 Erin Catto http://www.box2d.org
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| *
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| * This software is provided 'as-is', without any express or implied
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| * warranty.  In no event will the authors be held liable for any damages
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| * 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
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| * freely, subject to the following restrictions:
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| * 1. The origin of this software must not be misrepresented; you must not
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| * claim that you wrote the original software. If you use this software
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| * in a product, an acknowledgment in the product documentation would be
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| * appreciated but is not required.
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| * 2. Altered source versions must be plainly marked as such, and must not be
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| * 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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| 
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| #include "Box2D/Dynamics/Joints/b2PrismaticJoint.h"
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| #include "Box2D/Dynamics/b2Body.h"
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| #include "Box2D/Dynamics/b2TimeStep.h"
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| 
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| // Linear constraint (point-to-line)
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| // d = p2 - p1 = x2 + r2 - x1 - r1
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| // C = dot(perp, d)
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| // Cdot = dot(d, cross(w1, perp)) + dot(perp, v2 + cross(w2, r2) - v1 - cross(w1, r1))
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| //      = -dot(perp, v1) - dot(cross(d + r1, perp), w1) + dot(perp, v2) + dot(cross(r2, perp), v2)
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| // J = [-perp, -cross(d + r1, perp), perp, cross(r2,perp)]
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| //
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| // Angular constraint
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| // C = a2 - a1 + a_initial
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| // Cdot = w2 - w1
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| // J = [0 0 -1 0 0 1]
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| //
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| // K = J * invM * JT
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| //
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| // J = [-a -s1 a s2]
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| //     [0  -1  0  1]
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| // a = perp
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| // s1 = cross(d + r1, a) = cross(p2 - x1, a)
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| // s2 = cross(r2, a) = cross(p2 - x2, a)
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| 
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| 
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| // Motor/Limit linear constraint
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| // C = dot(ax1, d)
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| // Cdot = = -dot(ax1, v1) - dot(cross(d + r1, ax1), w1) + dot(ax1, v2) + dot(cross(r2, ax1), v2)
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| // J = [-ax1 -cross(d+r1,ax1) ax1 cross(r2,ax1)]
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| 
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| // Block Solver
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| // We develop a block solver that includes the joint limit. This makes the limit stiff (inelastic) even
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| // when the mass has poor distribution (leading to large torques about the joint anchor points).
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| //
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| // The Jacobian has 3 rows:
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| // J = [-uT -s1 uT s2] // linear
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| //     [0   -1   0  1] // angular
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| //     [-vT -a1 vT a2] // limit
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| //
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| // u = perp
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| // v = axis
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| // s1 = cross(d + r1, u), s2 = cross(r2, u)
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| // a1 = cross(d + r1, v), a2 = cross(r2, v)
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| 
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| // M * (v2 - v1) = JT * df
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| // J * v2 = bias
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| //
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| // v2 = v1 + invM * JT * df
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| // J * (v1 + invM * JT * df) = bias
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| // K * df = bias - J * v1 = -Cdot
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| // K = J * invM * JT
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| // Cdot = J * v1 - bias
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| //
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| // Now solve for f2.
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| // df = f2 - f1
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| // K * (f2 - f1) = -Cdot
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| // f2 = invK * (-Cdot) + f1
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| //
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| // Clamp accumulated limit impulse.
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| // lower: f2(3) = max(f2(3), 0)
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| // upper: f2(3) = min(f2(3), 0)
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| //
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| // Solve for correct f2(1:2)
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| // K(1:2, 1:2) * f2(1:2) = -Cdot(1:2) - K(1:2,3) * f2(3) + K(1:2,1:3) * f1
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| //                       = -Cdot(1:2) - K(1:2,3) * f2(3) + K(1:2,1:2) * f1(1:2) + K(1:2,3) * f1(3)
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| // K(1:2, 1:2) * f2(1:2) = -Cdot(1:2) - K(1:2,3) * (f2(3) - f1(3)) + K(1:2,1:2) * f1(1:2)
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| // f2(1:2) = invK(1:2,1:2) * (-Cdot(1:2) - K(1:2,3) * (f2(3) - f1(3))) + f1(1:2)
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| //
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| // Now compute impulse to be applied:
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| // df = f2 - f1
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| 
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| void b2PrismaticJointDef::Initialize(b2Body* bA, b2Body* bB, const b2Vec2& anchor, const b2Vec2& axis)
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| {
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| 	bodyA = bA;
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| 	bodyB = bB;
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| 	localAnchorA = bodyA->GetLocalPoint(anchor);
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| 	localAnchorB = bodyB->GetLocalPoint(anchor);
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| 	localAxisA = bodyA->GetLocalVector(axis);
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| 	referenceAngle = bodyB->GetAngle() - bodyA->GetAngle();
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| }
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| 
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| b2PrismaticJoint::b2PrismaticJoint(const b2PrismaticJointDef* def)
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| : b2Joint(def)
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| {
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| 	m_localAnchorA = def->localAnchorA;
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| 	m_localAnchorB = def->localAnchorB;
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| 	m_localXAxisA = def->localAxisA;
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| 	m_localXAxisA.Normalize();
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| 	m_localYAxisA = b2Cross(1.0f, m_localXAxisA);
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| 	m_referenceAngle = def->referenceAngle;
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| 
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| 	m_impulse.SetZero();
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| 	m_motorMass = 0.0f;
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| 	m_motorImpulse = 0.0f;
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| 
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| 	m_lowerTranslation = def->lowerTranslation;
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| 	m_upperTranslation = def->upperTranslation;
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| 	m_maxMotorForce = def->maxMotorForce;
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| 	m_motorSpeed = def->motorSpeed;
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| 	m_enableLimit = def->enableLimit;
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| 	m_enableMotor = def->enableMotor;
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| 	m_limitState = e_inactiveLimit;
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| 
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| 	m_axis.SetZero();
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| 	m_perp.SetZero();
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| }
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| 
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| void b2PrismaticJoint::InitVelocityConstraints(const b2SolverData& data)
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| {
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| 	m_indexA = m_bodyA->m_islandIndex;
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| 	m_indexB = m_bodyB->m_islandIndex;
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| 	m_localCenterA = m_bodyA->m_sweep.localCenter;
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| 	m_localCenterB = m_bodyB->m_sweep.localCenter;
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| 	m_invMassA = m_bodyA->m_invMass;
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| 	m_invMassB = m_bodyB->m_invMass;
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| 	m_invIA = m_bodyA->m_invI;
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| 	m_invIB = m_bodyB->m_invI;
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| 
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| 	b2Vec2 cA = data.positions[m_indexA].c;
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| 	float32 aA = data.positions[m_indexA].a;
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| 	b2Vec2 vA = data.velocities[m_indexA].v;
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| 	float32 wA = data.velocities[m_indexA].w;
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| 
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| 	b2Vec2 cB = data.positions[m_indexB].c;
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| 	float32 aB = data.positions[m_indexB].a;
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| 	b2Vec2 vB = data.velocities[m_indexB].v;
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| 	float32 wB = data.velocities[m_indexB].w;
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| 
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| 	b2Rot qA(aA), qB(aB);
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| 
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| 	// Compute the effective masses.
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| 	b2Vec2 rA = b2Mul(qA, m_localAnchorA - m_localCenterA);
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| 	b2Vec2 rB = b2Mul(qB, m_localAnchorB - m_localCenterB);
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| 	b2Vec2 d = (cB - cA) + rB - rA;
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| 
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| 	float32 mA = m_invMassA, mB = m_invMassB;
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| 	float32 iA = m_invIA, iB = m_invIB;
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| 
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| 	// Compute motor Jacobian and effective mass.
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| 	{
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| 		m_axis = b2Mul(qA, m_localXAxisA);
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| 		m_a1 = b2Cross(d + rA, m_axis);
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| 		m_a2 = b2Cross(rB, m_axis);
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| 
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| 		m_motorMass = mA + mB + iA * m_a1 * m_a1 + iB * m_a2 * m_a2;
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| 		if (m_motorMass > 0.0f)
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| 		{
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| 			m_motorMass = 1.0f / m_motorMass;
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| 		}
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| 	}
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| 
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| 	// Prismatic constraint.
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| 	{
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| 		m_perp = b2Mul(qA, m_localYAxisA);
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| 
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| 		m_s1 = b2Cross(d + rA, m_perp);
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| 		m_s2 = b2Cross(rB, m_perp);
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| 
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| 		float32 k11 = mA + mB + iA * m_s1 * m_s1 + iB * m_s2 * m_s2;
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| 		float32 k12 = iA * m_s1 + iB * m_s2;
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| 		float32 k13 = iA * m_s1 * m_a1 + iB * m_s2 * m_a2;
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| 		float32 k22 = iA + iB;
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| 		if (k22 == 0.0f)
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| 		{
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| 			// For bodies with fixed rotation.
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| 			k22 = 1.0f;
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| 		}
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| 		float32 k23 = iA * m_a1 + iB * m_a2;
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| 		float32 k33 = mA + mB + iA * m_a1 * m_a1 + iB * m_a2 * m_a2;
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| 
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| 		m_K.ex.Set(k11, k12, k13);
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| 		m_K.ey.Set(k12, k22, k23);
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| 		m_K.ez.Set(k13, k23, k33);
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| 	}
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| 
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| 	// Compute motor and limit terms.
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| 	if (m_enableLimit)
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| 	{
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| 		float32 jointTranslation = b2Dot(m_axis, d);
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| 		if (b2Abs(m_upperTranslation - m_lowerTranslation) < 2.0f * b2_linearSlop)
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| 		{
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| 			m_limitState = e_equalLimits;
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| 		}
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| 		else if (jointTranslation <= m_lowerTranslation)
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| 		{
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| 			if (m_limitState != e_atLowerLimit)
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| 			{
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| 				m_limitState = e_atLowerLimit;
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| 				m_impulse.z = 0.0f;
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| 			}
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| 		}
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| 		else if (jointTranslation >= m_upperTranslation)
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| 		{
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| 			if (m_limitState != e_atUpperLimit)
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| 			{
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| 				m_limitState = e_atUpperLimit;
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| 				m_impulse.z = 0.0f;
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| 			}
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| 		}
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| 		else
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| 		{
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| 			m_limitState = e_inactiveLimit;
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| 			m_impulse.z = 0.0f;
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| 		}
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| 	}
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| 	else
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| 	{
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| 		m_limitState = e_inactiveLimit;
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| 		m_impulse.z = 0.0f;
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| 	}
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| 
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| 	if (m_enableMotor == false)
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| 	{
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| 		m_motorImpulse = 0.0f;
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| 	}
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| 
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| 	if (data.step.warmStarting)
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| 	{
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| 		// Account for variable time step.
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| 		m_impulse *= data.step.dtRatio;
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| 		m_motorImpulse *= data.step.dtRatio;
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| 
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| 		b2Vec2 P = m_impulse.x * m_perp + (m_motorImpulse + m_impulse.z) * m_axis;
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| 		float32 LA = m_impulse.x * m_s1 + m_impulse.y + (m_motorImpulse + m_impulse.z) * m_a1;
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| 		float32 LB = m_impulse.x * m_s2 + m_impulse.y + (m_motorImpulse + m_impulse.z) * m_a2;
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| 
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| 		vA -= mA * P;
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| 		wA -= iA * LA;
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| 
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| 		vB += mB * P;
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| 		wB += iB * LB;
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| 	}
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| 	else
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| 	{
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| 		m_impulse.SetZero();
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| 		m_motorImpulse = 0.0f;
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| 	}
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| 
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| 	data.velocities[m_indexA].v = vA;
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| 	data.velocities[m_indexA].w = wA;
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| 	data.velocities[m_indexB].v = vB;
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| 	data.velocities[m_indexB].w = wB;
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| }
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| 
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| void b2PrismaticJoint::SolveVelocityConstraints(const b2SolverData& data)
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| {
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| 	b2Vec2 vA = data.velocities[m_indexA].v;
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| 	float32 wA = data.velocities[m_indexA].w;
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| 	b2Vec2 vB = data.velocities[m_indexB].v;
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| 	float32 wB = data.velocities[m_indexB].w;
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| 
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| 	float32 mA = m_invMassA, mB = m_invMassB;
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| 	float32 iA = m_invIA, iB = m_invIB;
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| 
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| 	// Solve linear motor constraint.
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| 	if (m_enableMotor && m_limitState != e_equalLimits)
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| 	{
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| 		float32 Cdot = b2Dot(m_axis, vB - vA) + m_a2 * wB - m_a1 * wA;
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| 		float32 impulse = m_motorMass * (m_motorSpeed - Cdot);
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| 		float32 oldImpulse = m_motorImpulse;
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| 		float32 maxImpulse = data.step.dt * m_maxMotorForce;
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| 		m_motorImpulse = b2Clamp(m_motorImpulse + impulse, -maxImpulse, maxImpulse);
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| 		impulse = m_motorImpulse - oldImpulse;
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| 
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| 		b2Vec2 P = impulse * m_axis;
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| 		float32 LA = impulse * m_a1;
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| 		float32 LB = impulse * m_a2;
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| 
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| 		vA -= mA * P;
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| 		wA -= iA * LA;
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| 
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| 		vB += mB * P;
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| 		wB += iB * LB;
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| 	}
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| 
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| 	b2Vec2 Cdot1;
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| 	Cdot1.x = b2Dot(m_perp, vB - vA) + m_s2 * wB - m_s1 * wA;
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| 	Cdot1.y = wB - wA;
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| 
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| 	if (m_enableLimit && m_limitState != e_inactiveLimit)
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| 	{
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| 		// Solve prismatic and limit constraint in block form.
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| 		float32 Cdot2;
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| 		Cdot2 = b2Dot(m_axis, vB - vA) + m_a2 * wB - m_a1 * wA;
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| 		b2Vec3 Cdot(Cdot1.x, Cdot1.y, Cdot2);
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| 
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| 		b2Vec3 f1 = m_impulse;
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| 		b2Vec3 df =  m_K.Solve33(-Cdot);
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| 		m_impulse += df;
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| 
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| 		if (m_limitState == e_atLowerLimit)
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| 		{
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| 			m_impulse.z = b2Max(m_impulse.z, 0.0f);
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| 		}
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| 		else if (m_limitState == e_atUpperLimit)
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| 		{
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| 			m_impulse.z = b2Min(m_impulse.z, 0.0f);
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| 		}
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| 
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| 		// f2(1:2) = invK(1:2,1:2) * (-Cdot(1:2) - K(1:2,3) * (f2(3) - f1(3))) + f1(1:2)
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| 		b2Vec2 b = -Cdot1 - (m_impulse.z - f1.z) * b2Vec2(m_K.ez.x, m_K.ez.y);
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| 		b2Vec2 f2r = m_K.Solve22(b) + b2Vec2(f1.x, f1.y);
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| 		m_impulse.x = f2r.x;
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| 		m_impulse.y = f2r.y;
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| 
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| 		df = m_impulse - f1;
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| 
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| 		b2Vec2 P = df.x * m_perp + df.z * m_axis;
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| 		float32 LA = df.x * m_s1 + df.y + df.z * m_a1;
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| 		float32 LB = df.x * m_s2 + df.y + df.z * m_a2;
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| 
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| 		vA -= mA * P;
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| 		wA -= iA * LA;
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| 
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| 		vB += mB * P;
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| 		wB += iB * LB;
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| 	}
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| 	else
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| 	{
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| 		// Limit is inactive, just solve the prismatic constraint in block form.
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| 		b2Vec2 df = m_K.Solve22(-Cdot1);
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| 		m_impulse.x += df.x;
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| 		m_impulse.y += df.y;
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| 
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| 		b2Vec2 P = df.x * m_perp;
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| 		float32 LA = df.x * m_s1 + df.y;
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| 		float32 LB = df.x * m_s2 + df.y;
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| 
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| 		vA -= mA * P;
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| 		wA -= iA * LA;
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| 
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| 		vB += mB * P;
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| 		wB += iB * LB;
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| 	}
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| 
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| 	data.velocities[m_indexA].v = vA;
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| 	data.velocities[m_indexA].w = wA;
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| 	data.velocities[m_indexB].v = vB;
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| 	data.velocities[m_indexB].w = wB;
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| }
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| 
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| // A velocity based solver computes reaction forces(impulses) using the velocity constraint solver.Under this context,
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| // the position solver is not there to resolve forces.It is only there to cope with integration error.
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| //
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| // Therefore, the pseudo impulses in the position solver do not have any physical meaning.Thus it is okay if they suck.
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| //
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| // We could take the active state from the velocity solver.However, the joint might push past the limit when the velocity
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| // solver indicates the limit is inactive.
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| bool b2PrismaticJoint::SolvePositionConstraints(const b2SolverData& data)
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| {
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| 	b2Vec2 cA = data.positions[m_indexA].c;
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| 	float32 aA = data.positions[m_indexA].a;
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| 	b2Vec2 cB = data.positions[m_indexB].c;
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| 	float32 aB = data.positions[m_indexB].a;
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| 
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| 	b2Rot qA(aA), qB(aB);
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| 
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| 	float32 mA = m_invMassA, mB = m_invMassB;
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| 	float32 iA = m_invIA, iB = m_invIB;
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| 
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| 	// Compute fresh Jacobians
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| 	b2Vec2 rA = b2Mul(qA, m_localAnchorA - m_localCenterA);
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| 	b2Vec2 rB = b2Mul(qB, m_localAnchorB - m_localCenterB);
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| 	b2Vec2 d = cB + rB - cA - rA;
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| 
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| 	b2Vec2 axis = b2Mul(qA, m_localXAxisA);
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| 	float32 a1 = b2Cross(d + rA, axis);
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| 	float32 a2 = b2Cross(rB, axis);
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| 	b2Vec2 perp = b2Mul(qA, m_localYAxisA);
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| 
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| 	float32 s1 = b2Cross(d + rA, perp);
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| 	float32 s2 = b2Cross(rB, perp);
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| 
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| 	b2Vec3 impulse;
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| 	b2Vec2 C1;
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| 	C1.x = b2Dot(perp, d);
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| 	C1.y = aB - aA - m_referenceAngle;
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| 
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| 	float32 linearError = b2Abs(C1.x);
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| 	float32 angularError = b2Abs(C1.y);
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| 
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| 	bool active = false;
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| 	float32 C2 = 0.0f;
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| 	if (m_enableLimit)
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| 	{
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| 		float32 translation = b2Dot(axis, d);
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| 		if (b2Abs(m_upperTranslation - m_lowerTranslation) < 2.0f * b2_linearSlop)
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| 		{
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| 			// Prevent large angular corrections
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| 			C2 = b2Clamp(translation, -b2_maxLinearCorrection, b2_maxLinearCorrection);
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| 			linearError = b2Max(linearError, b2Abs(translation));
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| 			active = true;
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| 		}
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| 		else if (translation <= m_lowerTranslation)
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| 		{
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| 			// Prevent large linear corrections and allow some slop.
 | |
| 			C2 = b2Clamp(translation - m_lowerTranslation + b2_linearSlop, -b2_maxLinearCorrection, 0.0f);
 | |
| 			linearError = b2Max(linearError, m_lowerTranslation - translation);
 | |
| 			active = true;
 | |
| 		}
 | |
| 		else if (translation >= m_upperTranslation)
 | |
| 		{
 | |
| 			// Prevent large linear corrections and allow some slop.
 | |
| 			C2 = b2Clamp(translation - m_upperTranslation - b2_linearSlop, 0.0f, b2_maxLinearCorrection);
 | |
| 			linearError = b2Max(linearError, translation - m_upperTranslation);
 | |
| 			active = true;
 | |
| 		}
 | |
| 	}
 | |
| 
 | |
| 	if (active)
 | |
| 	{
 | |
| 		float32 k11 = mA + mB + iA * s1 * s1 + iB * s2 * s2;
 | |
| 		float32 k12 = iA * s1 + iB * s2;
 | |
| 		float32 k13 = iA * s1 * a1 + iB * s2 * a2;
 | |
| 		float32 k22 = iA + iB;
 | |
| 		if (k22 == 0.0f)
 | |
| 		{
 | |
| 			// For fixed rotation
 | |
| 			k22 = 1.0f;
 | |
| 		}
 | |
| 		float32 k23 = iA * a1 + iB * a2;
 | |
| 		float32 k33 = mA + mB + iA * a1 * a1 + iB * a2 * a2;
 | |
| 
 | |
| 		b2Mat33 K;
 | |
| 		K.ex.Set(k11, k12, k13);
 | |
| 		K.ey.Set(k12, k22, k23);
 | |
| 		K.ez.Set(k13, k23, k33);
 | |
| 
 | |
| 		b2Vec3 C;
 | |
| 		C.x = C1.x;
 | |
| 		C.y = C1.y;
 | |
| 		C.z = C2;
 | |
| 
 | |
| 		impulse = K.Solve33(-C);
 | |
| 	}
 | |
| 	else
 | |
| 	{
 | |
| 		float32 k11 = mA + mB + iA * s1 * s1 + iB * s2 * s2;
 | |
| 		float32 k12 = iA * s1 + iB * s2;
 | |
| 		float32 k22 = iA + iB;
 | |
| 		if (k22 == 0.0f)
 | |
| 		{
 | |
| 			k22 = 1.0f;
 | |
| 		}
 | |
| 
 | |
| 		b2Mat22 K;
 | |
| 		K.ex.Set(k11, k12);
 | |
| 		K.ey.Set(k12, k22);
 | |
| 
 | |
| 		b2Vec2 impulse1 = K.Solve(-C1);
 | |
| 		impulse.x = impulse1.x;
 | |
| 		impulse.y = impulse1.y;
 | |
| 		impulse.z = 0.0f;
 | |
| 	}
 | |
| 
 | |
| 	b2Vec2 P = impulse.x * perp + impulse.z * axis;
 | |
| 	float32 LA = impulse.x * s1 + impulse.y + impulse.z * a1;
 | |
| 	float32 LB = impulse.x * s2 + impulse.y + impulse.z * a2;
 | |
| 
 | |
| 	cA -= mA * P;
 | |
| 	aA -= iA * LA;
 | |
| 	cB += mB * P;
 | |
| 	aB += iB * LB;
 | |
| 
 | |
| 	data.positions[m_indexA].c = cA;
 | |
| 	data.positions[m_indexA].a = aA;
 | |
| 	data.positions[m_indexB].c = cB;
 | |
| 	data.positions[m_indexB].a = aB;
 | |
| 
 | |
| 	return linearError <= b2_linearSlop && angularError <= b2_angularSlop;
 | |
| }
 | |
| 
 | |
| b2Vec2 b2PrismaticJoint::GetAnchorA() const
 | |
| {
 | |
| 	return m_bodyA->GetWorldPoint(m_localAnchorA);
 | |
| }
 | |
| 
 | |
| b2Vec2 b2PrismaticJoint::GetAnchorB() const
 | |
| {
 | |
| 	return m_bodyB->GetWorldPoint(m_localAnchorB);
 | |
| }
 | |
| 
 | |
| b2Vec2 b2PrismaticJoint::GetReactionForce(float32 inv_dt) const
 | |
| {
 | |
| 	return inv_dt * (m_impulse.x * m_perp + (m_motorImpulse + m_impulse.z) * m_axis);
 | |
| }
 | |
| 
 | |
| float32 b2PrismaticJoint::GetReactionTorque(float32 inv_dt) const
 | |
| {
 | |
| 	return inv_dt * m_impulse.y;
 | |
| }
 | |
| 
 | |
| float32 b2PrismaticJoint::GetJointTranslation() const
 | |
| {
 | |
| 	b2Vec2 pA = m_bodyA->GetWorldPoint(m_localAnchorA);
 | |
| 	b2Vec2 pB = m_bodyB->GetWorldPoint(m_localAnchorB);
 | |
| 	b2Vec2 d = pB - pA;
 | |
| 	b2Vec2 axis = m_bodyA->GetWorldVector(m_localXAxisA);
 | |
| 
 | |
| 	float32 translation = b2Dot(d, axis);
 | |
| 	return translation;
 | |
| }
 | |
| 
 | |
| float32 b2PrismaticJoint::GetJointSpeed() const
 | |
| {
 | |
| 	b2Body* bA = m_bodyA;
 | |
| 	b2Body* bB = m_bodyB;
 | |
| 
 | |
| 	b2Vec2 rA = b2Mul(bA->m_xf.q, m_localAnchorA - bA->m_sweep.localCenter);
 | |
| 	b2Vec2 rB = b2Mul(bB->m_xf.q, m_localAnchorB - bB->m_sweep.localCenter);
 | |
| 	b2Vec2 p1 = bA->m_sweep.c + rA;
 | |
| 	b2Vec2 p2 = bB->m_sweep.c + rB;
 | |
| 	b2Vec2 d = p2 - p1;
 | |
| 	b2Vec2 axis = b2Mul(bA->m_xf.q, m_localXAxisA);
 | |
| 
 | |
| 	b2Vec2 vA = bA->m_linearVelocity;
 | |
| 	b2Vec2 vB = bB->m_linearVelocity;
 | |
| 	float32 wA = bA->m_angularVelocity;
 | |
| 	float32 wB = bB->m_angularVelocity;
 | |
| 
 | |
| 	float32 speed = b2Dot(d, b2Cross(wA, axis)) + b2Dot(axis, vB + b2Cross(wB, rB) - vA - b2Cross(wA, rA));
 | |
| 	return speed;
 | |
| }
 | |
| 
 | |
| bool b2PrismaticJoint::IsLimitEnabled() const
 | |
| {
 | |
| 	return m_enableLimit;
 | |
| }
 | |
| 
 | |
| void b2PrismaticJoint::EnableLimit(bool flag)
 | |
| {
 | |
| 	if (flag != m_enableLimit)
 | |
| 	{
 | |
| 		m_bodyA->SetAwake(true);
 | |
| 		m_bodyB->SetAwake(true);
 | |
| 		m_enableLimit = flag;
 | |
| 		m_impulse.z = 0.0f;
 | |
| 	}
 | |
| }
 | |
| 
 | |
| float32 b2PrismaticJoint::GetLowerLimit() const
 | |
| {
 | |
| 	return m_lowerTranslation;
 | |
| }
 | |
| 
 | |
| float32 b2PrismaticJoint::GetUpperLimit() const
 | |
| {
 | |
| 	return m_upperTranslation;
 | |
| }
 | |
| 
 | |
| void b2PrismaticJoint::SetLimits(float32 lower, float32 upper)
 | |
| {
 | |
| 	b2Assert(lower <= upper);
 | |
| 	if (lower != m_lowerTranslation || upper != m_upperTranslation)
 | |
| 	{
 | |
| 		m_bodyA->SetAwake(true);
 | |
| 		m_bodyB->SetAwake(true);
 | |
| 		m_lowerTranslation = lower;
 | |
| 		m_upperTranslation = upper;
 | |
| 		m_impulse.z = 0.0f;
 | |
| 	}
 | |
| }
 | |
| 
 | |
| bool b2PrismaticJoint::IsMotorEnabled() const
 | |
| {
 | |
| 	return m_enableMotor;
 | |
| }
 | |
| 
 | |
| void b2PrismaticJoint::EnableMotor(bool flag)
 | |
| {
 | |
| 	if (flag != m_enableMotor)
 | |
| 	{
 | |
| 		m_bodyA->SetAwake(true);
 | |
| 		m_bodyB->SetAwake(true);
 | |
| 		m_enableMotor = flag;
 | |
| 	}
 | |
| }
 | |
| 
 | |
| void b2PrismaticJoint::SetMotorSpeed(float32 speed)
 | |
| {
 | |
| 	if (speed != m_motorSpeed)
 | |
| 	{
 | |
| 		m_bodyA->SetAwake(true);
 | |
| 		m_bodyB->SetAwake(true);
 | |
| 		m_motorSpeed = speed;
 | |
| 	}
 | |
| }
 | |
| 
 | |
| void b2PrismaticJoint::SetMaxMotorForce(float32 force)
 | |
| {
 | |
| 	if (force != m_maxMotorForce)
 | |
| 	{
 | |
| 		m_bodyA->SetAwake(true);
 | |
| 		m_bodyB->SetAwake(true);
 | |
| 		m_maxMotorForce = force;
 | |
| 	}
 | |
| }
 | |
| 
 | |
| float32 b2PrismaticJoint::GetMotorForce(float32 inv_dt) const
 | |
| {
 | |
| 	return inv_dt * m_motorImpulse;
 | |
| }
 | |
| 
 | |
| void b2PrismaticJoint::Dump()
 | |
| {
 | |
| 	int32 indexA = m_bodyA->m_islandIndex;
 | |
| 	int32 indexB = m_bodyB->m_islandIndex;
 | |
| 
 | |
| 	b2Log("  b2PrismaticJointDef jd;\n");
 | |
| 	b2Log("  jd.bodyA = bodies[%d];\n", indexA);
 | |
| 	b2Log("  jd.bodyB = bodies[%d];\n", indexB);
 | |
| 	b2Log("  jd.collideConnected = bool(%d);\n", m_collideConnected);
 | |
| 	b2Log("  jd.localAnchorA.Set(%.15lef, %.15lef);\n", m_localAnchorA.x, m_localAnchorA.y);
 | |
| 	b2Log("  jd.localAnchorB.Set(%.15lef, %.15lef);\n", m_localAnchorB.x, m_localAnchorB.y);
 | |
| 	b2Log("  jd.localAxisA.Set(%.15lef, %.15lef);\n", m_localXAxisA.x, m_localXAxisA.y);
 | |
| 	b2Log("  jd.referenceAngle = %.15lef;\n", m_referenceAngle);
 | |
| 	b2Log("  jd.enableLimit = bool(%d);\n", m_enableLimit);
 | |
| 	b2Log("  jd.lowerTranslation = %.15lef;\n", m_lowerTranslation);
 | |
| 	b2Log("  jd.upperTranslation = %.15lef;\n", m_upperTranslation);
 | |
| 	b2Log("  jd.enableMotor = bool(%d);\n", m_enableMotor);
 | |
| 	b2Log("  jd.motorSpeed = %.15lef;\n", m_motorSpeed);
 | |
| 	b2Log("  jd.maxMotorForce = %.15lef;\n", m_maxMotorForce);
 | |
| 	b2Log("  joints[%d] = m_world->CreateJoint(&jd);\n", m_index);
 | |
| }
 |