aboutsummaryrefslogtreecommitdiff
path: root/src/3rdparty/Box2D/Dynamics/Joints/b2RevoluteJoint.cpp
diff options
context:
space:
mode:
Diffstat (limited to 'src/3rdparty/Box2D/Dynamics/Joints/b2RevoluteJoint.cpp')
-rw-r--r--src/3rdparty/Box2D/Dynamics/Joints/b2RevoluteJoint.cpp511
1 files changed, 511 insertions, 0 deletions
diff --git a/src/3rdparty/Box2D/Dynamics/Joints/b2RevoluteJoint.cpp b/src/3rdparty/Box2D/Dynamics/Joints/b2RevoluteJoint.cpp
new file mode 100644
index 0000000..b3f7ee5
--- /dev/null
+++ b/src/3rdparty/Box2D/Dynamics/Joints/b2RevoluteJoint.cpp
@@ -0,0 +1,511 @@
+/*
+* Copyright (c) 2006-2011 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 "Box2D/Dynamics/Joints/b2RevoluteJoint.h"
+#include "Box2D/Dynamics/b2Body.h"
+#include "Box2D/Dynamics/b2TimeStep.h"
+
+// Point-to-point constraint
+// C = p2 - p1
+// Cdot = v2 - v1
+// = v2 + cross(w2, r2) - v1 - cross(w1, r1)
+// J = [-I -r1_skew I r2_skew ]
+// Identity used:
+// w k % (rx i + ry j) = w * (-ry i + rx j)
+
+// Motor constraint
+// Cdot = w2 - w1
+// J = [0 0 -1 0 0 1]
+// K = invI1 + invI2
+
+void b2RevoluteJointDef::Initialize(b2Body* bA, b2Body* bB, const b2Vec2& anchor)
+{
+ bodyA = bA;
+ bodyB = bB;
+ localAnchorA = bodyA->GetLocalPoint(anchor);
+ localAnchorB = bodyB->GetLocalPoint(anchor);
+ referenceAngle = bodyB->GetAngle() - bodyA->GetAngle();
+}
+
+b2RevoluteJoint::b2RevoluteJoint(const b2RevoluteJointDef* def)
+: b2Joint(def)
+{
+ m_localAnchorA = def->localAnchorA;
+ m_localAnchorB = def->localAnchorB;
+ m_referenceAngle = def->referenceAngle;
+
+ m_impulse.SetZero();
+ m_motorImpulse = 0.0f;
+
+ m_lowerAngle = def->lowerAngle;
+ m_upperAngle = def->upperAngle;
+ m_maxMotorTorque = def->maxMotorTorque;
+ m_motorSpeed = def->motorSpeed;
+ m_enableLimit = def->enableLimit;
+ m_enableMotor = def->enableMotor;
+ m_limitState = e_inactiveLimit;
+}
+
+void b2RevoluteJoint::InitVelocityConstraints(const b2SolverData& data)
+{
+ m_indexA = m_bodyA->m_islandIndex;
+ m_indexB = m_bodyB->m_islandIndex;
+ m_localCenterA = m_bodyA->m_sweep.localCenter;
+ m_localCenterB = m_bodyB->m_sweep.localCenter;
+ m_invMassA = m_bodyA->m_invMass;
+ m_invMassB = m_bodyB->m_invMass;
+ m_invIA = m_bodyA->m_invI;
+ m_invIB = m_bodyB->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;
+
+ b2Rot qA(aA), qB(aB);
+
+ m_rA = b2Mul(qA, m_localAnchorA - m_localCenterA);
+ m_rB = b2Mul(qB, m_localAnchorB - m_localCenterB);
+
+ // J = [-I -r1_skew I r2_skew]
+ // [ 0 -1 0 1]
+ // r_skew = [-ry; rx]
+
+ // Matlab
+ // K = [ mA+r1y^2*iA+mB+r2y^2*iB, -r1y*iA*r1x-r2y*iB*r2x, -r1y*iA-r2y*iB]
+ // [ -r1y*iA*r1x-r2y*iB*r2x, mA+r1x^2*iA+mB+r2x^2*iB, r1x*iA+r2x*iB]
+ // [ -r1y*iA-r2y*iB, r1x*iA+r2x*iB, iA+iB]
+
+ float32 mA = m_invMassA, mB = m_invMassB;
+ float32 iA = m_invIA, iB = m_invIB;
+
+ bool fixedRotation = (iA + iB == 0.0f);
+
+ m_mass.ex.x = mA + mB + m_rA.y * m_rA.y * iA + m_rB.y * m_rB.y * iB;
+ m_mass.ey.x = -m_rA.y * m_rA.x * iA - m_rB.y * m_rB.x * iB;
+ m_mass.ez.x = -m_rA.y * iA - m_rB.y * iB;
+ m_mass.ex.y = m_mass.ey.x;
+ m_mass.ey.y = mA + mB + m_rA.x * m_rA.x * iA + m_rB.x * m_rB.x * iB;
+ m_mass.ez.y = m_rA.x * iA + m_rB.x * iB;
+ m_mass.ex.z = m_mass.ez.x;
+ m_mass.ey.z = m_mass.ez.y;
+ m_mass.ez.z = iA + iB;
+
+ m_motorMass = iA + iB;
+ if (m_motorMass > 0.0f)
+ {
+ m_motorMass = 1.0f / m_motorMass;
+ }
+
+ if (m_enableMotor == false || fixedRotation)
+ {
+ m_motorImpulse = 0.0f;
+ }
+
+ if (m_enableLimit && fixedRotation == false)
+ {
+ float32 jointAngle = aB - aA - m_referenceAngle;
+ if (b2Abs(m_upperAngle - m_lowerAngle) < 2.0f * b2_angularSlop)
+ {
+ m_limitState = e_equalLimits;
+ }
+ else if (jointAngle <= m_lowerAngle)
+ {
+ if (m_limitState != e_atLowerLimit)
+ {
+ m_impulse.z = 0.0f;
+ }
+ m_limitState = e_atLowerLimit;
+ }
+ else if (jointAngle >= m_upperAngle)
+ {
+ if (m_limitState != e_atUpperLimit)
+ {
+ m_impulse.z = 0.0f;
+ }
+ m_limitState = e_atUpperLimit;
+ }
+ else
+ {
+ m_limitState = e_inactiveLimit;
+ m_impulse.z = 0.0f;
+ }
+ }
+ else
+ {
+ m_limitState = e_inactiveLimit;
+ }
+
+ if (data.step.warmStarting)
+ {
+ // Scale impulses to support a variable time step.
+ m_impulse *= data.step.dtRatio;
+ m_motorImpulse *= data.step.dtRatio;
+
+ b2Vec2 P(m_impulse.x, m_impulse.y);
+
+ vA -= mA * P;
+ wA -= iA * (b2Cross(m_rA, P) + m_motorImpulse + m_impulse.z);
+
+ vB += mB * P;
+ wB += iB * (b2Cross(m_rB, P) + m_motorImpulse + m_impulse.z);
+ }
+ else
+ {
+ m_impulse.SetZero();
+ m_motorImpulse = 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;
+}
+
+void b2RevoluteJoint::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;
+
+ float32 mA = m_invMassA, mB = m_invMassB;
+ float32 iA = m_invIA, iB = m_invIB;
+
+ bool fixedRotation = (iA + iB == 0.0f);
+
+ // Solve motor constraint.
+ if (m_enableMotor && m_limitState != e_equalLimits && fixedRotation == false)
+ {
+ float32 Cdot = wB - wA - m_motorSpeed;
+ float32 impulse = -m_motorMass * Cdot;
+ float32 oldImpulse = m_motorImpulse;
+ float32 maxImpulse = data.step.dt * m_maxMotorTorque;
+ m_motorImpulse = b2Clamp(m_motorImpulse + impulse, -maxImpulse, maxImpulse);
+ impulse = m_motorImpulse - oldImpulse;
+
+ wA -= iA * impulse;
+ wB += iB * impulse;
+ }
+
+ // Solve limit constraint.
+ if (m_enableLimit && m_limitState != e_inactiveLimit && fixedRotation == false)
+ {
+ b2Vec2 Cdot1 = vB + b2Cross(wB, m_rB) - vA - b2Cross(wA, m_rA);
+ float32 Cdot2 = wB - wA;
+ b2Vec3 Cdot(Cdot1.x, Cdot1.y, Cdot2);
+
+ b2Vec3 impulse = -m_mass.Solve33(Cdot);
+
+ if (m_limitState == e_equalLimits)
+ {
+ m_impulse += impulse;
+ }
+ else if (m_limitState == e_atLowerLimit)
+ {
+ float32 newImpulse = m_impulse.z + impulse.z;
+ if (newImpulse < 0.0f)
+ {
+ b2Vec2 rhs = -Cdot1 + m_impulse.z * b2Vec2(m_mass.ez.x, m_mass.ez.y);
+ b2Vec2 reduced = m_mass.Solve22(rhs);
+ impulse.x = reduced.x;
+ impulse.y = reduced.y;
+ impulse.z = -m_impulse.z;
+ m_impulse.x += reduced.x;
+ m_impulse.y += reduced.y;
+ m_impulse.z = 0.0f;
+ }
+ else
+ {
+ m_impulse += impulse;
+ }
+ }
+ else if (m_limitState == e_atUpperLimit)
+ {
+ float32 newImpulse = m_impulse.z + impulse.z;
+ if (newImpulse > 0.0f)
+ {
+ b2Vec2 rhs = -Cdot1 + m_impulse.z * b2Vec2(m_mass.ez.x, m_mass.ez.y);
+ b2Vec2 reduced = m_mass.Solve22(rhs);
+ impulse.x = reduced.x;
+ impulse.y = reduced.y;
+ impulse.z = -m_impulse.z;
+ m_impulse.x += reduced.x;
+ m_impulse.y += reduced.y;
+ m_impulse.z = 0.0f;
+ }
+ else
+ {
+ m_impulse += impulse;
+ }
+ }
+
+ b2Vec2 P(impulse.x, impulse.y);
+
+ vA -= mA * P;
+ wA -= iA * (b2Cross(m_rA, P) + impulse.z);
+
+ vB += mB * P;
+ wB += iB * (b2Cross(m_rB, P) + impulse.z);
+ }
+ else
+ {
+ // Solve point-to-point constraint
+ b2Vec2 Cdot = vB + b2Cross(wB, m_rB) - vA - b2Cross(wA, m_rA);
+ b2Vec2 impulse = m_mass.Solve22(-Cdot);
+
+ m_impulse.x += impulse.x;
+ m_impulse.y += impulse.y;
+
+ vA -= mA * impulse;
+ wA -= iA * b2Cross(m_rA, impulse);
+
+ vB += mB * impulse;
+ wB += iB * b2Cross(m_rB, impulse);
+ }
+
+ data.velocities[m_indexA].v = vA;
+ data.velocities[m_indexA].w = wA;
+ data.velocities[m_indexB].v = vB;
+ data.velocities[m_indexB].w = wB;
+}
+
+bool b2RevoluteJoint::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;
+
+ b2Rot qA(aA), qB(aB);
+
+ float32 angularError = 0.0f;
+ float32 positionError = 0.0f;
+
+ bool fixedRotation = (m_invIA + m_invIB == 0.0f);
+
+ // Solve angular limit constraint.
+ if (m_enableLimit && m_limitState != e_inactiveLimit && fixedRotation == false)
+ {
+ float32 angle = aB - aA - m_referenceAngle;
+ float32 limitImpulse = 0.0f;
+
+ if (m_limitState == e_equalLimits)
+ {
+ // Prevent large angular corrections
+ float32 C = b2Clamp(angle - m_lowerAngle, -b2_maxAngularCorrection, b2_maxAngularCorrection);
+ limitImpulse = -m_motorMass * C;
+ angularError = b2Abs(C);
+ }
+ else if (m_limitState == e_atLowerLimit)
+ {
+ float32 C = angle - m_lowerAngle;
+ angularError = -C;
+
+ // Prevent large angular corrections and allow some slop.
+ C = b2Clamp(C + b2_angularSlop, -b2_maxAngularCorrection, 0.0f);
+ limitImpulse = -m_motorMass * C;
+ }
+ else if (m_limitState == e_atUpperLimit)
+ {
+ float32 C = angle - m_upperAngle;
+ angularError = C;
+
+ // Prevent large angular corrections and allow some slop.
+ C = b2Clamp(C - b2_angularSlop, 0.0f, b2_maxAngularCorrection);
+ limitImpulse = -m_motorMass * C;
+ }
+
+ aA -= m_invIA * limitImpulse;
+ aB += m_invIB * limitImpulse;
+ }
+
+ // Solve point-to-point constraint.
+ {
+ qA.Set(aA);
+ qB.Set(aB);
+ b2Vec2 rA = b2Mul(qA, m_localAnchorA - m_localCenterA);
+ b2Vec2 rB = b2Mul(qB, m_localAnchorB - m_localCenterB);
+
+ b2Vec2 C = cB + rB - cA - rA;
+ positionError = C.Length();
+
+ float32 mA = m_invMassA, mB = m_invMassB;
+ float32 iA = m_invIA, iB = m_invIB;
+
+ b2Mat22 K;
+ K.ex.x = mA + mB + iA * rA.y * rA.y + iB * rB.y * rB.y;
+ K.ex.y = -iA * rA.x * rA.y - iB * rB.x * rB.y;
+ K.ey.x = K.ex.y;
+ K.ey.y = mA + mB + iA * rA.x * rA.x + iB * rB.x * rB.x;
+
+ b2Vec2 impulse = -K.Solve(C);
+
+ cA -= mA * impulse;
+ aA -= iA * b2Cross(rA, impulse);
+
+ cB += mB * impulse;
+ aB += iB * b2Cross(rB, impulse);
+ }
+
+ 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 positionError <= b2_linearSlop && angularError <= b2_angularSlop;
+}
+
+b2Vec2 b2RevoluteJoint::GetAnchorA() const
+{
+ return m_bodyA->GetWorldPoint(m_localAnchorA);
+}
+
+b2Vec2 b2RevoluteJoint::GetAnchorB() const
+{
+ return m_bodyB->GetWorldPoint(m_localAnchorB);
+}
+
+b2Vec2 b2RevoluteJoint::GetReactionForce(float32 inv_dt) const
+{
+ b2Vec2 P(m_impulse.x, m_impulse.y);
+ return inv_dt * P;
+}
+
+float32 b2RevoluteJoint::GetReactionTorque(float32 inv_dt) const
+{
+ return inv_dt * m_impulse.z;
+}
+
+float32 b2RevoluteJoint::GetJointAngle() const
+{
+ b2Body* bA = m_bodyA;
+ b2Body* bB = m_bodyB;
+ return bB->m_sweep.a - bA->m_sweep.a - m_referenceAngle;
+}
+
+float32 b2RevoluteJoint::GetJointSpeed() const
+{
+ b2Body* bA = m_bodyA;
+ b2Body* bB = m_bodyB;
+ return bB->m_angularVelocity - bA->m_angularVelocity;
+}
+
+bool b2RevoluteJoint::IsMotorEnabled() const
+{
+ return m_enableMotor;
+}
+
+void b2RevoluteJoint::EnableMotor(bool flag)
+{
+ if (flag != m_enableMotor)
+ {
+ m_bodyA->SetAwake(true);
+ m_bodyB->SetAwake(true);
+ m_enableMotor = flag;
+ }
+}
+
+float32 b2RevoluteJoint::GetMotorTorque(float32 inv_dt) const
+{
+ return inv_dt * m_motorImpulse;
+}
+
+void b2RevoluteJoint::SetMotorSpeed(float32 speed)
+{
+ if (speed != m_motorSpeed)
+ {
+ m_bodyA->SetAwake(true);
+ m_bodyB->SetAwake(true);
+ m_motorSpeed = speed;
+ }
+}
+
+void b2RevoluteJoint::SetMaxMotorTorque(float32 torque)
+{
+ if (torque != m_maxMotorTorque)
+ {
+ m_bodyA->SetAwake(true);
+ m_bodyB->SetAwake(true);
+ m_maxMotorTorque = torque;
+ }
+}
+
+bool b2RevoluteJoint::IsLimitEnabled() const
+{
+ return m_enableLimit;
+}
+
+void b2RevoluteJoint::EnableLimit(bool flag)
+{
+ if (flag != m_enableLimit)
+ {
+ m_bodyA->SetAwake(true);
+ m_bodyB->SetAwake(true);
+ m_enableLimit = flag;
+ m_impulse.z = 0.0f;
+ }
+}
+
+float32 b2RevoluteJoint::GetLowerLimit() const
+{
+ return m_lowerAngle;
+}
+
+float32 b2RevoluteJoint::GetUpperLimit() const
+{
+ return m_upperAngle;
+}
+
+void b2RevoluteJoint::SetLimits(float32 lower, float32 upper)
+{
+ b2Assert(lower <= upper);
+
+ if (lower != m_lowerAngle || upper != m_upperAngle)
+ {
+ m_bodyA->SetAwake(true);
+ m_bodyB->SetAwake(true);
+ m_impulse.z = 0.0f;
+ m_lowerAngle = lower;
+ m_upperAngle = upper;
+ }
+}
+
+void b2RevoluteJoint::Dump()
+{
+ int32 indexA = m_bodyA->m_islandIndex;
+ int32 indexB = m_bodyB->m_islandIndex;
+
+ b2Log(" b2RevoluteJointDef 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.referenceAngle = %.15lef;\n", m_referenceAngle);
+ b2Log(" jd.enableLimit = bool(%d);\n", m_enableLimit);
+ b2Log(" jd.lowerAngle = %.15lef;\n", m_lowerAngle);
+ b2Log(" jd.upperAngle = %.15lef;\n", m_upperAngle);
+ b2Log(" jd.enableMotor = bool(%d);\n", m_enableMotor);
+ b2Log(" jd.motorSpeed = %.15lef;\n", m_motorSpeed);
+ b2Log(" jd.maxMotorTorque = %.15lef;\n", m_maxMotorTorque);
+ b2Log(" joints[%d] = m_world->CreateJoint(&jd);\n", m_index);
+}
generated by cgit v1.1-26-g67d0 at 2025-05-18 21:03:58 +0000