diff options
Diffstat (limited to 'Client/ThirdParty/Box2D/src/dynamics/b2_weld_joint.cpp')
| -rw-r--r-- | Client/ThirdParty/Box2D/src/dynamics/b2_weld_joint.cpp | 344 |
1 files changed, 344 insertions, 0 deletions
diff --git a/Client/ThirdParty/Box2D/src/dynamics/b2_weld_joint.cpp b/Client/ThirdParty/Box2D/src/dynamics/b2_weld_joint.cpp new file mode 100644 index 0000000..df3ee0a --- /dev/null +++ b/Client/ThirdParty/Box2D/src/dynamics/b2_weld_joint.cpp @@ -0,0 +1,344 @@ +// MIT License + +// Copyright (c) 2019 Erin Catto + +// Permission is hereby granted, free of charge, to any person obtaining a copy +// of this software and associated documentation files (the "Software"), to deal +// in the Software without restriction, including without limitation the rights +// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +// copies of the Software, and to permit persons to whom the Software is +// furnished to do so, subject to the following conditions: + +// The above copyright notice and this permission notice shall be included in all +// copies or substantial portions of the Software. + +// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +// SOFTWARE. + +#include "box2d/b2_body.h" +#include "box2d/b2_time_step.h" +#include "box2d/b2_weld_joint.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) + +// Angle constraint +// C = angle2 - angle1 - referenceAngle +// Cdot = w2 - w1 +// J = [0 0 -1 0 0 1] +// K = invI1 + invI2 + +void b2WeldJointDef::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(); +} + +b2WeldJoint::b2WeldJoint(const b2WeldJointDef* def) +: b2Joint(def) +{ + m_localAnchorA = def->localAnchorA; + m_localAnchorB = def->localAnchorB; + m_referenceAngle = def->referenceAngle; + m_stiffness = def->stiffness; + m_damping = def->damping; + + m_impulse.SetZero(); +} + +void b2WeldJoint::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; + + float aA = data.positions[m_indexA].a; + b2Vec2 vA = data.velocities[m_indexA].v; + float wA = data.velocities[m_indexA].w; + + float aB = data.positions[m_indexB].a; + b2Vec2 vB = data.velocities[m_indexB].v; + float 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] + + float mA = m_invMassA, mB = m_invMassB; + float iA = m_invIA, iB = m_invIB; + + b2Mat33 K; + K.ex.x = mA + mB + m_rA.y * m_rA.y * iA + m_rB.y * m_rB.y * iB; + K.ey.x = -m_rA.y * m_rA.x * iA - m_rB.y * m_rB.x * iB; + K.ez.x = -m_rA.y * iA - m_rB.y * iB; + K.ex.y = K.ey.x; + K.ey.y = mA + mB + m_rA.x * m_rA.x * iA + m_rB.x * m_rB.x * iB; + K.ez.y = m_rA.x * iA + m_rB.x * iB; + K.ex.z = K.ez.x; + K.ey.z = K.ez.y; + K.ez.z = iA + iB; + + if (m_stiffness > 0.0f) + { + K.GetInverse22(&m_mass); + + float invM = iA + iB; + + float C = aB - aA - m_referenceAngle; + + // Damping coefficient + float d = m_damping; + + // Spring stiffness + float k = m_stiffness; + + // magic formulas + float h = data.step.dt; + m_gamma = h * (d + h * k); + m_gamma = m_gamma != 0.0f ? 1.0f / m_gamma : 0.0f; + m_bias = C * h * k * m_gamma; + + invM += m_gamma; + m_mass.ez.z = invM != 0.0f ? 1.0f / invM : 0.0f; + } + else if (K.ez.z == 0.0f) + { + K.GetInverse22(&m_mass); + m_gamma = 0.0f; + m_bias = 0.0f; + } + else + { + K.GetSymInverse33(&m_mass); + m_gamma = 0.0f; + m_bias = 0.0f; + } + + if (data.step.warmStarting) + { + // Scale impulses to support a variable time step. + m_impulse *= data.step.dtRatio; + + b2Vec2 P(m_impulse.x, m_impulse.y); + + vA -= mA * P; + wA -= iA * (b2Cross(m_rA, P) + m_impulse.z); + + vB += mB * P; + wB += iB * (b2Cross(m_rB, P) + m_impulse.z); + } + else + { + m_impulse.SetZero(); + } + + 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 b2WeldJoint::SolveVelocityConstraints(const b2SolverData& data) +{ + b2Vec2 vA = data.velocities[m_indexA].v; + float wA = data.velocities[m_indexA].w; + b2Vec2 vB = data.velocities[m_indexB].v; + float wB = data.velocities[m_indexB].w; + + float mA = m_invMassA, mB = m_invMassB; + float iA = m_invIA, iB = m_invIB; + + if (m_stiffness > 0.0f) + { + float Cdot2 = wB - wA; + + float impulse2 = -m_mass.ez.z * (Cdot2 + m_bias + m_gamma * m_impulse.z); + m_impulse.z += impulse2; + + wA -= iA * impulse2; + wB += iB * impulse2; + + b2Vec2 Cdot1 = vB + b2Cross(wB, m_rB) - vA - b2Cross(wA, m_rA); + + b2Vec2 impulse1 = -b2Mul22(m_mass, Cdot1); + m_impulse.x += impulse1.x; + m_impulse.y += impulse1.y; + + b2Vec2 P = impulse1; + + vA -= mA * P; + wA -= iA * b2Cross(m_rA, P); + + vB += mB * P; + wB += iB * b2Cross(m_rB, P); + } + else + { + b2Vec2 Cdot1 = vB + b2Cross(wB, m_rB) - vA - b2Cross(wA, m_rA); + float Cdot2 = wB - wA; + b2Vec3 Cdot(Cdot1.x, Cdot1.y, Cdot2); + + b2Vec3 impulse = -b2Mul(m_mass, Cdot); + 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); + } + + 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 b2WeldJoint::SolvePositionConstraints(const b2SolverData& data) +{ + b2Vec2 cA = data.positions[m_indexA].c; + float aA = data.positions[m_indexA].a; + b2Vec2 cB = data.positions[m_indexB].c; + float aB = data.positions[m_indexB].a; + + b2Rot qA(aA), qB(aB); + + float mA = m_invMassA, mB = m_invMassB; + float iA = m_invIA, iB = m_invIB; + + b2Vec2 rA = b2Mul(qA, m_localAnchorA - m_localCenterA); + b2Vec2 rB = b2Mul(qB, m_localAnchorB - m_localCenterB); + + float positionError, angularError; + + b2Mat33 K; + K.ex.x = mA + mB + rA.y * rA.y * iA + rB.y * rB.y * iB; + K.ey.x = -rA.y * rA.x * iA - rB.y * rB.x * iB; + K.ez.x = -rA.y * iA - rB.y * iB; + K.ex.y = K.ey.x; + K.ey.y = mA + mB + rA.x * rA.x * iA + rB.x * rB.x * iB; + K.ez.y = rA.x * iA + rB.x * iB; + K.ex.z = K.ez.x; + K.ey.z = K.ez.y; + K.ez.z = iA + iB; + + if (m_stiffness > 0.0f) + { + b2Vec2 C1 = cB + rB - cA - rA; + + positionError = C1.Length(); + angularError = 0.0f; + + b2Vec2 P = -K.Solve22(C1); + + cA -= mA * P; + aA -= iA * b2Cross(rA, P); + + cB += mB * P; + aB += iB * b2Cross(rB, P); + } + else + { + b2Vec2 C1 = cB + rB - cA - rA; + float C2 = aB - aA - m_referenceAngle; + + positionError = C1.Length(); + angularError = b2Abs(C2); + + b2Vec3 C(C1.x, C1.y, C2); + + b2Vec3 impulse; + if (K.ez.z > 0.0f) + { + impulse = -K.Solve33(C); + } + else + { + b2Vec2 impulse2 = -K.Solve22(C1); + impulse.Set(impulse2.x, impulse2.y, 0.0f); + } + + b2Vec2 P(impulse.x, impulse.y); + + cA -= mA * P; + aA -= iA * (b2Cross(rA, P) + impulse.z); + + cB += mB * P; + aB += iB * (b2Cross(rB, P) + impulse.z); + } + + 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 b2WeldJoint::GetAnchorA() const +{ + return m_bodyA->GetWorldPoint(m_localAnchorA); +} + +b2Vec2 b2WeldJoint::GetAnchorB() const +{ + return m_bodyB->GetWorldPoint(m_localAnchorB); +} + +b2Vec2 b2WeldJoint::GetReactionForce(float inv_dt) const +{ + b2Vec2 P(m_impulse.x, m_impulse.y); + return inv_dt * P; +} + +float b2WeldJoint::GetReactionTorque(float inv_dt) const +{ + return inv_dt * m_impulse.z; +} + +void b2WeldJoint::Dump() +{ + int32 indexA = m_bodyA->m_islandIndex; + int32 indexB = m_bodyB->m_islandIndex; + + b2Dump(" b2WeldJointDef jd;\n"); + b2Dump(" jd.bodyA = bodies[%d];\n", indexA); + b2Dump(" jd.bodyB = bodies[%d];\n", indexB); + b2Dump(" jd.collideConnected = bool(%d);\n", m_collideConnected); + b2Dump(" jd.localAnchorA.Set(%.9g, %.9g);\n", m_localAnchorA.x, m_localAnchorA.y); + b2Dump(" jd.localAnchorB.Set(%.9g, %.9g);\n", m_localAnchorB.x, m_localAnchorB.y); + b2Dump(" jd.referenceAngle = %.9g;\n", m_referenceAngle); + b2Dump(" jd.stiffness = %.9g;\n", m_stiffness); + b2Dump(" jd.damping = %.9g;\n", m_damping); + b2Dump(" joints[%d] = m_world->CreateJoint(&jd);\n", m_index); +} |