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paulxstretch/deps/juce/modules/juce_box2d/box2d/Dynamics/Joints/b2GearJoint.cpp
essej 25bd5d8adb git subrepo clone --branch=sono6good https://github.com/essej/JUCE.git deps/juce 
subrepo:
  subdir:   "deps/juce"
  merged:   "b13f9084e"
upstream:
  origin:   "https://github.com/essej/JUCE.git"
  branch:   "sono6good"
  commit:   "b13f9084e"
git-subrepo:
  version:  "0.4.3"
  origin:   "https://github.com/ingydotnet/git-subrepo.git"
  commit:   "2f68596"
2022-04-18 17:51:22 -04:00

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/*
* Copyright (c) 2007-2011 Erin Catto http://www.box2d.org
*
* 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 "b2GearJoint.h"
#include "b2RevoluteJoint.h"
#include "b2PrismaticJoint.h"
#include "../b2Body.h"
#include "../b2TimeStep.h"
// Gear Joint:
// C0 = (coordinate1 + ratio * coordinate2)_initial
// C = (coordinate1 + ratio * coordinate2) - C0 = 0
// J = [J1 ratio * J2]
// K = J * invM * JT
// = J1 * invM1 * J1T + ratio * ratio * J2 * invM2 * J2T
//
// Revolute:
// coordinate = rotation
// Cdot = angularVelocity
// J = [0 0 1]
// K = J * invM * JT = invI
//
// Prismatic:
// coordinate = dot(p - pg, ug)
// Cdot = dot(v + cross(w, r), ug)
// J = [ug cross(r, ug)]
// K = J * invM * JT = invMass + invI * cross(r, ug)^2
b2GearJoint::b2GearJoint(const b2GearJointDef* def)
: b2Joint(def)
{
m_joint1 = def->joint1;
m_joint2 = def->joint2;
m_typeA = m_joint1->GetType();
m_typeB = m_joint2->GetType();
b2Assert(m_typeA == e_revoluteJoint || m_typeA == e_prismaticJoint);
b2Assert(m_typeB == e_revoluteJoint || m_typeB == e_prismaticJoint);
float32 coordinateA, coordinateB;
// TODO_ERIN there might be some problem with the joint edges in b2Joint.
m_bodyC = m_joint1->GetBodyA();
m_bodyA = m_joint1->GetBodyB();
// Get geometry of joint1
b2Transform xfA = m_bodyA->m_xf;
float32 aA = m_bodyA->m_sweep.a;
b2Transform xfC = m_bodyC->m_xf;
float32 aC = m_bodyC->m_sweep.a;
if (m_typeA == e_revoluteJoint)
{
b2RevoluteJoint* revolute = (b2RevoluteJoint*)def->joint1;
m_localAnchorC = revolute->m_localAnchorA;
m_localAnchorA = revolute->m_localAnchorB;
m_referenceAngleA = revolute->m_referenceAngle;
m_localAxisC.SetZero();
coordinateA = aA - aC - m_referenceAngleA;
}
else
{
b2PrismaticJoint* prismatic = (b2PrismaticJoint*)def->joint1;
m_localAnchorC = prismatic->m_localAnchorA;
m_localAnchorA = prismatic->m_localAnchorB;
m_referenceAngleA = prismatic->m_referenceAngle;
m_localAxisC = prismatic->m_localXAxisA;
b2Vec2 pC = m_localAnchorC;
b2Vec2 pA = b2MulT(xfC.q, b2Mul(xfA.q, m_localAnchorA) + (xfA.p - xfC.p));
coordinateA = b2Dot(pA - pC, m_localAxisC);
}
m_bodyD = m_joint2->GetBodyA();
m_bodyB = m_joint2->GetBodyB();
// Get geometry of joint2
b2Transform xfB = m_bodyB->m_xf;
float32 aB = m_bodyB->m_sweep.a;
b2Transform xfD = m_bodyD->m_xf;
float32 aD = m_bodyD->m_sweep.a;
if (m_typeB == e_revoluteJoint)
{
b2RevoluteJoint* revolute = (b2RevoluteJoint*)def->joint2;
m_localAnchorD = revolute->m_localAnchorA;
m_localAnchorB = revolute->m_localAnchorB;
m_referenceAngleB = revolute->m_referenceAngle;
m_localAxisD.SetZero();
coordinateB = aB - aD - m_referenceAngleB;
}
else
{
b2PrismaticJoint* prismatic = (b2PrismaticJoint*)def->joint2;
m_localAnchorD = prismatic->m_localAnchorA;
m_localAnchorB = prismatic->m_localAnchorB;
m_referenceAngleB = prismatic->m_referenceAngle;
m_localAxisD = prismatic->m_localXAxisA;
b2Vec2 pD = m_localAnchorD;
b2Vec2 pB = b2MulT(xfD.q, b2Mul(xfB.q, m_localAnchorB) + (xfB.p - xfD.p));
coordinateB = b2Dot(pB - pD, m_localAxisD);
}
m_ratio = def->ratio;
m_constant = coordinateA + m_ratio * coordinateB;
m_impulse = 0.0f;
}
void b2GearJoint::InitVelocityConstraints(const b2SolverData& data)
{
m_indexA = m_bodyA->m_islandIndex;
m_indexB = m_bodyB->m_islandIndex;
m_indexC = m_bodyC->m_islandIndex;
m_indexD = m_bodyD->m_islandIndex;
m_lcA = m_bodyA->m_sweep.localCenter;
m_lcB = m_bodyB->m_sweep.localCenter;
m_lcC = m_bodyC->m_sweep.localCenter;
m_lcD = m_bodyD->m_sweep.localCenter;
m_mA = m_bodyA->m_invMass;
m_mB = m_bodyB->m_invMass;
m_mC = m_bodyC->m_invMass;
m_mD = m_bodyD->m_invMass;
m_iA = m_bodyA->m_invI;
m_iB = m_bodyB->m_invI;
m_iC = m_bodyC->m_invI;
m_iD = m_bodyD->m_invI;
float32 aA = data.positions[m_indexA].a;
b2Vec2 vA = data.velocities[m_indexA].v;
float32 wA = data.velocities[m_indexA].w;
float32 aB = data.positions[m_indexB].a;
b2Vec2 vB = data.velocities[m_indexB].v;
float32 wB = data.velocities[m_indexB].w;
float32 aC = data.positions[m_indexC].a;
b2Vec2 vC = data.velocities[m_indexC].v;
float32 wC = data.velocities[m_indexC].w;
float32 aD = data.positions[m_indexD].a;
b2Vec2 vD = data.velocities[m_indexD].v;
float32 wD = data.velocities[m_indexD].w;
b2Rot qA(aA), qB(aB), qC(aC), qD(aD);
m_mass = 0.0f;
if (m_typeA == e_revoluteJoint)
{
m_JvAC.SetZero();
m_JwA = 1.0f;
m_JwC = 1.0f;
m_mass += m_iA + m_iC;
}
else
{
b2Vec2 u = b2Mul(qC, m_localAxisC);
b2Vec2 rC = b2Mul(qC, m_localAnchorC - m_lcC);
b2Vec2 rA = b2Mul(qA, m_localAnchorA - m_lcA);
m_JvAC = u;
m_JwC = b2Cross(rC, u);
m_JwA = b2Cross(rA, u);
m_mass += m_mC + m_mA + m_iC * m_JwC * m_JwC + m_iA * m_JwA * m_JwA;
}
if (m_typeB == e_revoluteJoint)
{
m_JvBD.SetZero();
m_JwB = m_ratio;
m_JwD = m_ratio;
m_mass += m_ratio * m_ratio * (m_iB + m_iD);
}
else
{
b2Vec2 u = b2Mul(qD, m_localAxisD);
b2Vec2 rD = b2Mul(qD, m_localAnchorD - m_lcD);
b2Vec2 rB = b2Mul(qB, m_localAnchorB - m_lcB);
m_JvBD = m_ratio * u;
m_JwD = m_ratio * b2Cross(rD, u);
m_JwB = m_ratio * b2Cross(rB, u);
m_mass += m_ratio * m_ratio * (m_mD + m_mB) + m_iD * m_JwD * m_JwD + m_iB * m_JwB * m_JwB;
}
// Compute effective mass.
m_mass = m_mass > 0.0f ? 1.0f / m_mass : 0.0f;
if (data.step.warmStarting)
{
vA += (m_mA * m_impulse) * m_JvAC;
wA += m_iA * m_impulse * m_JwA;
vB += (m_mB * m_impulse) * m_JvBD;
wB += m_iB * m_impulse * m_JwB;
vC -= (m_mC * m_impulse) * m_JvAC;
wC -= m_iC * m_impulse * m_JwC;
vD -= (m_mD * m_impulse) * m_JvBD;
wD -= m_iD * m_impulse * m_JwD;
}
else
{
m_impulse = 0.0f;
}
data.velocities[m_indexA].v = vA;
data.velocities[m_indexA].w = wA;
data.velocities[m_indexB].v = vB;
data.velocities[m_indexB].w = wB;
data.velocities[m_indexC].v = vC;
data.velocities[m_indexC].w = wC;
data.velocities[m_indexD].v = vD;
data.velocities[m_indexD].w = wD;
}
void b2GearJoint::SolveVelocityConstraints(const b2SolverData& data)
{
b2Vec2 vA = data.velocities[m_indexA].v;
float32 wA = data.velocities[m_indexA].w;
b2Vec2 vB = data.velocities[m_indexB].v;
float32 wB = data.velocities[m_indexB].w;
b2Vec2 vC = data.velocities[m_indexC].v;
float32 wC = data.velocities[m_indexC].w;
b2Vec2 vD = data.velocities[m_indexD].v;
float32 wD = data.velocities[m_indexD].w;
float32 Cdot = b2Dot(m_JvAC, vA - vC) + b2Dot(m_JvBD, vB - vD);
Cdot += (m_JwA * wA - m_JwC * wC) + (m_JwB * wB - m_JwD * wD);
float32 impulse = -m_mass * Cdot;
m_impulse += impulse;
vA += (m_mA * impulse) * m_JvAC;
wA += m_iA * impulse * m_JwA;
vB += (m_mB * impulse) * m_JvBD;
wB += m_iB * impulse * m_JwB;
vC -= (m_mC * impulse) * m_JvAC;
wC -= m_iC * impulse * m_JwC;
vD -= (m_mD * impulse) * m_JvBD;
wD -= m_iD * impulse * m_JwD;
data.velocities[m_indexA].v = vA;
data.velocities[m_indexA].w = wA;
data.velocities[m_indexB].v = vB;
data.velocities[m_indexB].w = wB;
data.velocities[m_indexC].v = vC;
data.velocities[m_indexC].w = wC;
data.velocities[m_indexD].v = vD;
data.velocities[m_indexD].w = wD;
}
bool b2GearJoint::SolvePositionConstraints(const b2SolverData& data)
{
b2Vec2 cA = data.positions[m_indexA].c;
float32 aA = data.positions[m_indexA].a;
b2Vec2 cB = data.positions[m_indexB].c;
float32 aB = data.positions[m_indexB].a;
b2Vec2 cC = data.positions[m_indexC].c;
float32 aC = data.positions[m_indexC].a;
b2Vec2 cD = data.positions[m_indexD].c;
float32 aD = data.positions[m_indexD].a;
b2Rot qA(aA), qB(aB), qC(aC), qD(aD);
float32 linearError = 0.0f;
float32 coordinateA, coordinateB;
b2Vec2 JvAC, JvBD;
float32 JwA, JwB, JwC, JwD;
float32 mass = 0.0f;
if (m_typeA == e_revoluteJoint)
{
JvAC.SetZero();
JwA = 1.0f;
JwC = 1.0f;
mass += m_iA + m_iC;
coordinateA = aA - aC - m_referenceAngleA;
}
else
{
b2Vec2 u = b2Mul(qC, m_localAxisC);
b2Vec2 rC = b2Mul(qC, m_localAnchorC - m_lcC);
b2Vec2 rA = b2Mul(qA, m_localAnchorA - m_lcA);
JvAC = u;
JwC = b2Cross(rC, u);
JwA = b2Cross(rA, u);
mass += m_mC + m_mA + m_iC * JwC * JwC + m_iA * JwA * JwA;
b2Vec2 pC = m_localAnchorC - m_lcC;
b2Vec2 pA = b2MulT(qC, rA + (cA - cC));
coordinateA = b2Dot(pA - pC, m_localAxisC);
}
if (m_typeB == e_revoluteJoint)
{
JvBD.SetZero();
JwB = m_ratio;
JwD = m_ratio;
mass += m_ratio * m_ratio * (m_iB + m_iD);
coordinateB = aB - aD - m_referenceAngleB;
}
else
{
b2Vec2 u = b2Mul(qD, m_localAxisD);
b2Vec2 rD = b2Mul(qD, m_localAnchorD - m_lcD);
b2Vec2 rB = b2Mul(qB, m_localAnchorB - m_lcB);
JvBD = m_ratio * u;
JwD = m_ratio * b2Cross(rD, u);
JwB = m_ratio * b2Cross(rB, u);
mass += m_ratio * m_ratio * (m_mD + m_mB) + m_iD * JwD * JwD + m_iB * JwB * JwB;
b2Vec2 pD = m_localAnchorD - m_lcD;
b2Vec2 pB = b2MulT(qD, rB + (cB - cD));
coordinateB = b2Dot(pB - pD, m_localAxisD);
}
float32 C = (coordinateA + m_ratio * coordinateB) - m_constant;
float32 impulse = 0.0f;
if (mass > 0.0f)
{
impulse = -C / mass;
}
cA += m_mA * impulse * JvAC;
aA += m_iA * impulse * JwA;
cB += m_mB * impulse * JvBD;
aB += m_iB * impulse * JwB;
cC -= m_mC * impulse * JvAC;
aC -= m_iC * impulse * JwC;
cD -= m_mD * impulse * JvBD;
aD -= m_iD * impulse * JwD;
data.positions[m_indexA].c = cA;
data.positions[m_indexA].a = aA;
data.positions[m_indexB].c = cB;
data.positions[m_indexB].a = aB;
data.positions[m_indexC].c = cC;
data.positions[m_indexC].a = aC;
data.positions[m_indexD].c = cD;
data.positions[m_indexD].a = aD;
// TODO_ERIN not implemented
return linearError < b2_linearSlop;
}
b2Vec2 b2GearJoint::GetAnchorA() const
{
return m_bodyA->GetWorldPoint(m_localAnchorA);
}
b2Vec2 b2GearJoint::GetAnchorB() const
{
return m_bodyB->GetWorldPoint(m_localAnchorB);
}
b2Vec2 b2GearJoint::GetReactionForce(float32 inv_dt) const
{
b2Vec2 P = m_impulse * m_JvAC;
return inv_dt * P;
}
float32 b2GearJoint::GetReactionTorque(float32 inv_dt) const
{
float32 L = m_impulse * m_JwA;
return inv_dt * L;
}
void b2GearJoint::SetRatio(float32 ratio)
{
b2Assert(b2IsValid(ratio));
m_ratio = ratio;
}
float32 b2GearJoint::GetRatio() const
{
return m_ratio;
}
void b2GearJoint::Dump()
{
int32 indexA = m_bodyA->m_islandIndex;
int32 indexB = m_bodyB->m_islandIndex;
int32 index1 = m_joint1->m_index;
int32 index2 = m_joint2->m_index;
b2Log(" b2GearJointDef 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.joint1 = joints[%d];\n", index1);
b2Log(" jd.joint2 = joints[%d];\n", index2);
b2Log(" jd.ratio = %.15lef;\n", m_ratio);
b2Log(" joints[%d] = m_world->CreateJoint(&jd);\n", m_index);
}
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