public void Initialize(ContactPositionConstraint pc, Transform xfA, Transform xfB, int index) { Utilities.Assert(pc.pointCount > 0); switch (pc.type) { case Manifold.ManifoldType.e_circles: { Vec2 pointA = Utilities.Mul(xfA, pc.localPoint); Vec2 pointB = Utilities.Mul(xfB, pc.localPoints[0]); normal = pointB - pointA; normal.Normalize(); point = 0.5f * (pointA + pointB); separation = Utilities.Dot(pointB - pointA, normal) - pc.radiusA - pc.radiusB; } break; case Manifold.ManifoldType.e_faceA: { normal = Utilities.Mul(xfA.q, pc.localNormal); Vec2 planePoint = Utilities.Mul(xfA, pc.localPoint); Vec2 clipPoint = Utilities.Mul(xfB, pc.localPoints[index]); separation = Utilities.Dot(clipPoint - planePoint, normal) - pc.radiusA - pc.radiusB; point = clipPoint; } break; case Manifold.ManifoldType.e_faceB: { normal = Utilities.Mul(xfB.q, pc.localNormal); Vec2 planePoint = Utilities.Mul(xfB, pc.localPoint); Vec2 clipPoint = Utilities.Mul(xfA, pc.localPoints[index]); separation = Utilities.Dot(clipPoint - planePoint, normal) - pc.radiusA - pc.radiusB; point = clipPoint; // Ensure normal points from A to B normal = -normal; } break; } }
public ContactSolver(ContactSolverDef def) { m_step = def.step; m_positionConstraints = new List<ContactPositionConstraint>(); m_velocityConstraints = new List<ContactVelocityConstraint>(); m_positions = def.positions; m_velocities = def.velocities; m_contacts = def.contacts; // Initialize position independent portions of the constraints. for (int i = 0; i < def.contacts.Count(); ++i) { Contact contact = m_contacts[i]; Fixture fixtureA = contact.m_fixtureA; Fixture fixtureB = contact.m_fixtureB; Shape shapeA = fixtureA.GetShape(); Shape shapeB = fixtureB.GetShape(); float radiusA = shapeA.m_radius; float radiusB = shapeB.m_radius; Body bodyA = fixtureA.GetBody(); Body bodyB = fixtureB.GetBody(); Manifold manifold = contact.GetManifold(); int pointCount = manifold.points.Count(); Utilities.Assert(pointCount > 0); ContactVelocityConstraint vc = new ContactVelocityConstraint(); vc.friction = contact.m_friction; vc.restitution = contact.m_restitution; vc.tangentSpeed = contact.m_tangentSpeed; vc.indexA = bodyA.m_islandIndex; vc.indexB = bodyB.m_islandIndex; vc.invMassA = bodyA.m_invMass; vc.invMassB = bodyB.m_invMass; vc.invIA = bodyA.m_invI; vc.invIB = bodyB.m_invI; vc.contactIndex = i; //vc.points.Count() = pointCount; vc.K.SetZero(); vc.normalMass.SetZero(); ContactPositionConstraint pc = new ContactPositionConstraint(); pc.indexA = bodyA.m_islandIndex; pc.indexB = bodyB.m_islandIndex; pc.invMassA = bodyA.m_invMass; pc.invMassB = bodyB.m_invMass; pc.localCenterA = bodyA.m_sweep.localCenter; pc.localCenterB = bodyB.m_sweep.localCenter; pc.invIA = bodyA.m_invI; pc.invIB = bodyB.m_invI; pc.localNormal = manifold.localNormal; pc.localPoint = manifold.localPoint; pc.pointCount = pointCount; pc.radiusA = radiusA; pc.radiusB = radiusB; pc.type = manifold.type; for (int j = 0; j < pointCount; ++j) { ManifoldPoint cp = manifold.points[j]; VelocityConstraintPoint vcp = new VelocityConstraintPoint(); if (m_step.warmStarting) { vcp.normalImpulse = m_step.dtRatio * cp.normalImpulse; vcp.tangentImpulse = m_step.dtRatio * cp.tangentImpulse; } else { vcp.normalImpulse = 0.0f; vcp.tangentImpulse = 0.0f; } vcp.rA.SetZero(); vcp.rB.SetZero(); vcp.normalMass = 0.0f; vcp.tangentMass = 0.0f; vcp.velocityBias = 0.0f; vc.points.Add(vcp); pc.localPoints[j] = cp.localPoint; } m_velocityConstraints.Add(vc); m_positionConstraints.Add(pc); } }
public ContactSolver(ContactSolverDef def) { m_step = def.step; m_positionConstraints = new List <ContactPositionConstraint>(); m_velocityConstraints = new List <ContactVelocityConstraint>(); m_positions = def.positions; m_velocities = def.velocities; m_contacts = def.contacts; // Initialize position independent portions of the constraints. for (int i = 0; i < def.contacts.Count(); ++i) { Contact contact = m_contacts[i]; Fixture fixtureA = contact.m_fixtureA; Fixture fixtureB = contact.m_fixtureB; Shape shapeA = fixtureA.GetShape(); Shape shapeB = fixtureB.GetShape(); float radiusA = shapeA.m_radius; float radiusB = shapeB.m_radius; Body bodyA = fixtureA.GetBody(); Body bodyB = fixtureB.GetBody(); Manifold manifold = contact.GetManifold(); int pointCount = manifold.points.Count(); Utilities.Assert(pointCount > 0); ContactVelocityConstraint vc = new ContactVelocityConstraint(); vc.friction = contact.m_friction; vc.restitution = contact.m_restitution; vc.tangentSpeed = contact.m_tangentSpeed; vc.indexA = bodyA.m_islandIndex; vc.indexB = bodyB.m_islandIndex; vc.invMassA = bodyA.m_invMass; vc.invMassB = bodyB.m_invMass; vc.invIA = bodyA.m_invI; vc.invIB = bodyB.m_invI; vc.contactIndex = i; //vc.points.Count() = pointCount; vc.K.SetZero(); vc.normalMass.SetZero(); ContactPositionConstraint pc = new ContactPositionConstraint(); pc.indexA = bodyA.m_islandIndex; pc.indexB = bodyB.m_islandIndex; pc.invMassA = bodyA.m_invMass; pc.invMassB = bodyB.m_invMass; pc.localCenterA = bodyA.m_sweep.localCenter; pc.localCenterB = bodyB.m_sweep.localCenter; pc.invIA = bodyA.m_invI; pc.invIB = bodyB.m_invI; pc.localNormal = manifold.localNormal; pc.localPoint = manifold.localPoint; pc.pointCount = pointCount; pc.radiusA = radiusA; pc.radiusB = radiusB; pc.type = manifold.type; for (int j = 0; j < pointCount; ++j) { ManifoldPoint cp = manifold.points[j]; VelocityConstraintPoint vcp = new VelocityConstraintPoint(); if (m_step.warmStarting) { vcp.normalImpulse = m_step.dtRatio * cp.normalImpulse; vcp.tangentImpulse = m_step.dtRatio * cp.tangentImpulse; } else { vcp.normalImpulse = 0.0f; vcp.tangentImpulse = 0.0f; } vcp.rA.SetZero(); vcp.rB.SetZero(); vcp.normalMass = 0.0f; vcp.tangentMass = 0.0f; vcp.velocityBias = 0.0f; vc.points.Add(vcp); pc.localPoints[j] = cp.localPoint; } m_velocityConstraints.Add(vc); m_positionConstraints.Add(pc); } }
public void InitializeVelocityConstraints() { for (int i = 0; i < m_contacts.Count(); ++i) { ContactVelocityConstraint vc = m_velocityConstraints[i]; ContactPositionConstraint pc = m_positionConstraints[i]; float radiusA = pc.radiusA; float radiusB = pc.radiusB; Manifold manifold = m_contacts[vc.contactIndex].GetManifold(); int indexA = vc.indexA; int indexB = vc.indexB; float mA = vc.invMassA; float mB = vc.invMassB; float iA = vc.invIA; float iB = vc.invIB; Vec2 localCenterA = pc.localCenterA; Vec2 localCenterB = pc.localCenterB; Vec2 cA = m_positions[indexA].c; float aA = m_positions[indexA].a; Vec2 vA = m_velocities[indexA].v; float wA = m_velocities[indexA].w; Vec2 cB = m_positions[indexB].c; float aB = m_positions[indexB].a; Vec2 vB = m_velocities[indexB].v; float wB = m_velocities[indexB].w; Utilities.Assert(manifold.points.Count() > 0); Transform xfA = new Transform(); Transform xfB = new Transform(); xfA.q.Set(aA); xfB.q.Set(aB); xfA.p = cA - Utilities.Mul(xfA.q, localCenterA); xfB.p = cB - Utilities.Mul(xfB.q, localCenterB); WorldManifold worldManifold = new WorldManifold(); worldManifold.Initialize(manifold, xfA, radiusA, xfB, radiusB); vc.normal = worldManifold.normal; int pointCount = vc.points.Count; for (int j = 0; j < pointCount; ++j) { VelocityConstraintPoint vcp = vc.points[j]; vcp.rA = worldManifold.points[j] - cA; vcp.rB = worldManifold.points[j] - cB; float rnA = Utilities.Cross(vcp.rA, vc.normal); float rnB = Utilities.Cross(vcp.rB, vc.normal); float kNormal = mA + mB + iA * rnA * rnA + iB * rnB * rnB; vcp.normalMass = kNormal > 0.0f ? 1.0f / kNormal : 0.0f; Vec2 tangent = Utilities.Cross(vc.normal, 1.0f); float rtA = Utilities.Cross(vcp.rA, tangent); float rtB = Utilities.Cross(vcp.rB, tangent); float kTangent = mA + mB + iA * rtA * rtA + iB * rtB * rtB; vcp.tangentMass = kTangent > 0.0f ? 1.0f / kTangent : 0.0f; // Setup a velocity bias for restitution. vcp.velocityBias = 0.0f; float vRel = Utilities.Dot(vc.normal, vB + Utilities.Cross(wB, vcp.rB) - vA - Utilities.Cross(wA, vcp.rA)); if (vRel < -Settings._velocityThreshold) { vcp.velocityBias = -vc.restitution * vRel; } } // If we have two points, then prepare the block solver. if (vc.points.Count() == 2) { VelocityConstraintPoint vcp1 = vc.points[0]; VelocityConstraintPoint vcp2 = vc.points[1]; float rn1A = Utilities.Cross(vcp1.rA, vc.normal); float rn1B = Utilities.Cross(vcp1.rB, vc.normal); float rn2A = Utilities.Cross(vcp2.rA, vc.normal); float rn2B = Utilities.Cross(vcp2.rB, vc.normal); float k11 = mA + mB + iA * rn1A * rn1A + iB * rn1B * rn1B; float k22 = mA + mB + iA * rn2A * rn2A + iB * rn2B * rn2B; float k12 = mA + mB + iA * rn1A * rn2A + iB * rn1B * rn2B; // Ensure a reasonable condition number. const float k_maxConditionNumber = 1000.0f; if (k11 * k11 < k_maxConditionNumber * (k11 * k22 - k12 * k12)) { // K is safe to invert. vc.K.ex.Set(k11, k12); vc.K.ey.Set(k12, k22); vc.normalMass = vc.K.GetInverse(); } else { // The constraints are redundant, just use one. // TODO_ERIN use deepest? vc.points.Clear(); vc.points.Add(new VelocityConstraintPoint()); } } } }
public bool SolvePositionConstraints() { float minSeparation = 0.0f; for (int i = 0; i < m_contacts.Count(); ++i) { ContactPositionConstraint pc = m_positionConstraints[i]; int indexA = pc.indexA; int indexB = pc.indexB; Vec2 localCenterA = pc.localCenterA; float mA = pc.invMassA; float iA = pc.invIA; Vec2 localCenterB = pc.localCenterB; float mB = pc.invMassB; float iB = pc.invIB; int pointCount = pc.pointCount; Vec2 cA = m_positions[indexA].c; float aA = m_positions[indexA].a; Vec2 cB = m_positions[indexB].c; float aB = m_positions[indexB].a; // Solve normal constraints for (int j = 0; j < pointCount; ++j) { Transform xfA = new Transform(); Transform xfB = new Transform(); xfA.q.Set(aA); xfB.q.Set(aB); xfA.p = cA - Utilities.Mul(xfA.q, localCenterA); xfB.p = cB - Utilities.Mul(xfB.q, localCenterB); PositionSolverManifold psm = new PositionSolverManifold(); psm.Initialize(pc, xfA, xfB, j); Vec2 normal = psm.normal; Vec2 point = psm.point; float separation = psm.separation; Vec2 rA = point - cA; Vec2 rB = point - cB; // Track max constraint error. minSeparation = Math.Min(minSeparation, separation); // Prevent large corrections and allow slop. float C = Utilities.Clamp(Settings._baumgarte * (separation + Settings._linearSlop), -Settings._maxLinearCorrection, 0.0f); // Compute the effective mass. float rnA = Utilities.Cross(rA, normal); float rnB = Utilities.Cross(rB, normal); float K = mA + mB + iA * rnA * rnA + iB * rnB * rnB; // Compute normal impulse float impulse = K > 0.0f ? -C / K : 0.0f; Vec2 P = impulse * normal; cA -= mA * P; aA -= iA * Utilities.Cross(rA, P); cB += mB * P; aB += iB * Utilities.Cross(rB, P); } m_positions[indexA].c = cA; m_positions[indexA].a = aA; m_positions[indexB].c = cB; m_positions[indexB].a = aB; } // We can't expect minSpeparation >= -_linearSlop because we don't // push the separation above -_linearSlop. return(minSeparation >= -3.0f * Settings._linearSlop); }