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Diffstat (limited to 'Source/3rdParty/Box2D/Dynamics/Contacts/b2ContactSolver.cpp')
| -rw-r--r-- | Source/3rdParty/Box2D/Dynamics/Contacts/b2ContactSolver.cpp | 838 |
1 files changed, 0 insertions, 838 deletions
diff --git a/Source/3rdParty/Box2D/Dynamics/Contacts/b2ContactSolver.cpp b/Source/3rdParty/Box2D/Dynamics/Contacts/b2ContactSolver.cpp deleted file mode 100644 index 147968c..0000000 --- a/Source/3rdParty/Box2D/Dynamics/Contacts/b2ContactSolver.cpp +++ /dev/null @@ -1,838 +0,0 @@ -/* -* 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/Contacts/b2ContactSolver.h" - -#include "Box2D/Dynamics/Contacts/b2Contact.h" -#include "Box2D/Dynamics/b2Body.h" -#include "Box2D/Dynamics/b2Fixture.h" -#include "Box2D/Dynamics/b2World.h" -#include "Box2D/Common/b2StackAllocator.h" - -// Solver debugging is normally disabled because the block solver sometimes has to deal with a poorly conditioned effective mass matrix. -#define B2_DEBUG_SOLVER 0 - -bool g_blockSolve = true; - -struct b2ContactPositionConstraint -{ - b2Vec2 localPoints[b2_maxManifoldPoints]; - b2Vec2 localNormal; - b2Vec2 localPoint; - int32 indexA; - int32 indexB; - float32 invMassA, invMassB; - b2Vec2 localCenterA, localCenterB; - float32 invIA, invIB; - b2Manifold::Type type; - float32 radiusA, radiusB; - int32 pointCount; -}; - -b2ContactSolver::b2ContactSolver(b2ContactSolverDef* def) -{ - m_step = def->step; - m_allocator = def->allocator; - m_count = def->count; - m_positionConstraints = (b2ContactPositionConstraint*)m_allocator->Allocate(m_count * sizeof(b2ContactPositionConstraint)); - m_velocityConstraints = (b2ContactVelocityConstraint*)m_allocator->Allocate(m_count * sizeof(b2ContactVelocityConstraint)); - m_positions = def->positions; - m_velocities = def->velocities; - m_contacts = def->contacts; - - // Initialize position independent portions of the constraints. - for (int32 i = 0; i < m_count; ++i) - { - b2Contact* contact = m_contacts[i]; - - b2Fixture* fixtureA = contact->m_fixtureA; - b2Fixture* fixtureB = contact->m_fixtureB; - b2Shape* shapeA = fixtureA->GetShape(); - b2Shape* shapeB = fixtureB->GetShape(); - float32 radiusA = shapeA->m_radius; - float32 radiusB = shapeB->m_radius; - b2Body* bodyA = fixtureA->GetBody(); - b2Body* bodyB = fixtureB->GetBody(); - b2Manifold* manifold = contact->GetManifold(); - - int32 pointCount = manifold->pointCount; - b2Assert(pointCount > 0); - - b2ContactVelocityConstraint* vc = m_velocityConstraints + i; - 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->pointCount = pointCount; - vc->K.SetZero(); - vc->normalMass.SetZero(); - - b2ContactPositionConstraint* pc = m_positionConstraints + i; - 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 (int32 j = 0; j < pointCount; ++j) - { - b2ManifoldPoint* cp = manifold->points + j; - b2VelocityConstraintPoint* vcp = vc->points + j; - - 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; - - pc->localPoints[j] = cp->localPoint; - } - } -} - -b2ContactSolver::~b2ContactSolver() -{ - m_allocator->Free(m_velocityConstraints); - m_allocator->Free(m_positionConstraints); -} - -// Initialize position dependent portions of the velocity constraints. -void b2ContactSolver::InitializeVelocityConstraints() -{ - for (int32 i = 0; i < m_count; ++i) - { - b2ContactVelocityConstraint* vc = m_velocityConstraints + i; - b2ContactPositionConstraint* pc = m_positionConstraints + i; - - float32 radiusA = pc->radiusA; - float32 radiusB = pc->radiusB; - b2Manifold* manifold = m_contacts[vc->contactIndex]->GetManifold(); - - int32 indexA = vc->indexA; - int32 indexB = vc->indexB; - - float32 mA = vc->invMassA; - float32 mB = vc->invMassB; - float32 iA = vc->invIA; - float32 iB = vc->invIB; - b2Vec2 localCenterA = pc->localCenterA; - b2Vec2 localCenterB = pc->localCenterB; - - b2Vec2 cA = m_positions[indexA].c; - float32 aA = m_positions[indexA].a; - b2Vec2 vA = m_velocities[indexA].v; - float32 wA = m_velocities[indexA].w; - - b2Vec2 cB = m_positions[indexB].c; - float32 aB = m_positions[indexB].a; - b2Vec2 vB = m_velocities[indexB].v; - float32 wB = m_velocities[indexB].w; - - b2Assert(manifold->pointCount > 0); - - b2Transform xfA, xfB; - xfA.q.Set(aA); - xfB.q.Set(aB); - xfA.p = cA - b2Mul(xfA.q, localCenterA); - xfB.p = cB - b2Mul(xfB.q, localCenterB); - - b2WorldManifold worldManifold; - worldManifold.Initialize(manifold, xfA, radiusA, xfB, radiusB); - - vc->normal = worldManifold.normal; - - int32 pointCount = vc->pointCount; - for (int32 j = 0; j < pointCount; ++j) - { - b2VelocityConstraintPoint* vcp = vc->points + j; - - vcp->rA = worldManifold.points[j] - cA; - vcp->rB = worldManifold.points[j] - cB; - - float32 rnA = b2Cross(vcp->rA, vc->normal); - float32 rnB = b2Cross(vcp->rB, vc->normal); - - float32 kNormal = mA + mB + iA * rnA * rnA + iB * rnB * rnB; - - vcp->normalMass = kNormal > 0.0f ? 1.0f / kNormal : 0.0f; - - b2Vec2 tangent = b2Cross(vc->normal, 1.0f); - - float32 rtA = b2Cross(vcp->rA, tangent); - float32 rtB = b2Cross(vcp->rB, tangent); - - float32 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; - float32 vRel = b2Dot(vc->normal, vB + b2Cross(wB, vcp->rB) - vA - b2Cross(wA, vcp->rA)); - if (vRel < -b2_velocityThreshold) - { - vcp->velocityBias = -vc->restitution * vRel; - } - } - - // If we have two points, then prepare the block solver. - if (vc->pointCount == 2 && g_blockSolve) - { - b2VelocityConstraintPoint* vcp1 = vc->points + 0; - b2VelocityConstraintPoint* vcp2 = vc->points + 1; - - float32 rn1A = b2Cross(vcp1->rA, vc->normal); - float32 rn1B = b2Cross(vcp1->rB, vc->normal); - float32 rn2A = b2Cross(vcp2->rA, vc->normal); - float32 rn2B = b2Cross(vcp2->rB, vc->normal); - - float32 k11 = mA + mB + iA * rn1A * rn1A + iB * rn1B * rn1B; - float32 k22 = mA + mB + iA * rn2A * rn2A + iB * rn2B * rn2B; - float32 k12 = mA + mB + iA * rn1A * rn2A + iB * rn1B * rn2B; - - // Ensure a reasonable condition number. - const float32 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->pointCount = 1; - } - } - } -} - -void b2ContactSolver::WarmStart() -{ - // Warm start. - for (int32 i = 0; i < m_count; ++i) - { - b2ContactVelocityConstraint* vc = m_velocityConstraints + i; - - int32 indexA = vc->indexA; - int32 indexB = vc->indexB; - float32 mA = vc->invMassA; - float32 iA = vc->invIA; - float32 mB = vc->invMassB; - float32 iB = vc->invIB; - int32 pointCount = vc->pointCount; - - b2Vec2 vA = m_velocities[indexA].v; - float32 wA = m_velocities[indexA].w; - b2Vec2 vB = m_velocities[indexB].v; - float32 wB = m_velocities[indexB].w; - - b2Vec2 normal = vc->normal; - b2Vec2 tangent = b2Cross(normal, 1.0f); - - for (int32 j = 0; j < pointCount; ++j) - { - b2VelocityConstraintPoint* vcp = vc->points + j; - b2Vec2 P = vcp->normalImpulse * normal + vcp->tangentImpulse * tangent; - wA -= iA * b2Cross(vcp->rA, P); - vA -= mA * P; - wB += iB * b2Cross(vcp->rB, P); - vB += mB * P; - } - - m_velocities[indexA].v = vA; - m_velocities[indexA].w = wA; - m_velocities[indexB].v = vB; - m_velocities[indexB].w = wB; - } -} - -void b2ContactSolver::SolveVelocityConstraints() -{ - for (int32 i = 0; i < m_count; ++i) - { - b2ContactVelocityConstraint* vc = m_velocityConstraints + i; - - int32 indexA = vc->indexA; - int32 indexB = vc->indexB; - float32 mA = vc->invMassA; - float32 iA = vc->invIA; - float32 mB = vc->invMassB; - float32 iB = vc->invIB; - int32 pointCount = vc->pointCount; - - b2Vec2 vA = m_velocities[indexA].v; - float32 wA = m_velocities[indexA].w; - b2Vec2 vB = m_velocities[indexB].v; - float32 wB = m_velocities[indexB].w; - - b2Vec2 normal = vc->normal; - b2Vec2 tangent = b2Cross(normal, 1.0f); - float32 friction = vc->friction; - - b2Assert(pointCount == 1 || pointCount == 2); - - // Solve tangent constraints first because non-penetration is more important - // than friction. - for (int32 j = 0; j < pointCount; ++j) - { - b2VelocityConstraintPoint* vcp = vc->points + j; - - // Relative velocity at contact - b2Vec2 dv = vB + b2Cross(wB, vcp->rB) - vA - b2Cross(wA, vcp->rA); - - // Compute tangent force - float32 vt = b2Dot(dv, tangent) - vc->tangentSpeed; - float32 lambda = vcp->tangentMass * (-vt); - - // b2Clamp the accumulated force - float32 maxFriction = friction * vcp->normalImpulse; - float32 newImpulse = b2Clamp(vcp->tangentImpulse + lambda, -maxFriction, maxFriction); - lambda = newImpulse - vcp->tangentImpulse; - vcp->tangentImpulse = newImpulse; - - // Apply contact impulse - b2Vec2 P = lambda * tangent; - - vA -= mA * P; - wA -= iA * b2Cross(vcp->rA, P); - - vB += mB * P; - wB += iB * b2Cross(vcp->rB, P); - } - - // Solve normal constraints - if (pointCount == 1 || g_blockSolve == false) - { - for (int32 j = 0; j < pointCount; ++j) - { - b2VelocityConstraintPoint* vcp = vc->points + j; - - // Relative velocity at contact - b2Vec2 dv = vB + b2Cross(wB, vcp->rB) - vA - b2Cross(wA, vcp->rA); - - // Compute normal impulse - float32 vn = b2Dot(dv, normal); - float32 lambda = -vcp->normalMass * (vn - vcp->velocityBias); - - // b2Clamp the accumulated impulse - float32 newImpulse = b2Max(vcp->normalImpulse + lambda, 0.0f); - lambda = newImpulse - vcp->normalImpulse; - vcp->normalImpulse = newImpulse; - - // Apply contact impulse - b2Vec2 P = lambda * normal; - vA -= mA * P; - wA -= iA * b2Cross(vcp->rA, P); - - vB += mB * P; - wB += iB * b2Cross(vcp->rB, P); - } - } - else - { - // Block solver developed in collaboration with Dirk Gregorius (back in 01/07 on Box2D_Lite). - // Build the mini LCP for this contact patch - // - // vn = A * x + b, vn >= 0, x >= 0 and vn_i * x_i = 0 with i = 1..2 - // - // A = J * W * JT and J = ( -n, -r1 x n, n, r2 x n ) - // b = vn0 - velocityBias - // - // The system is solved using the "Total enumeration method" (s. Murty). The complementary constraint vn_i * x_i - // implies that we must have in any solution either vn_i = 0 or x_i = 0. So for the 2D contact problem the cases - // vn1 = 0 and vn2 = 0, x1 = 0 and x2 = 0, x1 = 0 and vn2 = 0, x2 = 0 and vn1 = 0 need to be tested. The first valid - // solution that satisfies the problem is chosen. - // - // In order to account of the accumulated impulse 'a' (because of the iterative nature of the solver which only requires - // that the accumulated impulse is clamped and not the incremental impulse) we change the impulse variable (x_i). - // - // Substitute: - // - // x = a + d - // - // a := old total impulse - // x := new total impulse - // d := incremental impulse - // - // For the current iteration we extend the formula for the incremental impulse - // to compute the new total impulse: - // - // vn = A * d + b - // = A * (x - a) + b - // = A * x + b - A * a - // = A * x + b' - // b' = b - A * a; - - b2VelocityConstraintPoint* cp1 = vc->points + 0; - b2VelocityConstraintPoint* cp2 = vc->points + 1; - - b2Vec2 a(cp1->normalImpulse, cp2->normalImpulse); - b2Assert(a.x >= 0.0f && a.y >= 0.0f); - - // Relative velocity at contact - b2Vec2 dv1 = vB + b2Cross(wB, cp1->rB) - vA - b2Cross(wA, cp1->rA); - b2Vec2 dv2 = vB + b2Cross(wB, cp2->rB) - vA - b2Cross(wA, cp2->rA); - - // Compute normal velocity - float32 vn1 = b2Dot(dv1, normal); - float32 vn2 = b2Dot(dv2, normal); - - b2Vec2 b; - b.x = vn1 - cp1->velocityBias; - b.y = vn2 - cp2->velocityBias; - - // Compute b' - b -= b2Mul(vc->K, a); - - const float32 k_errorTol = 1e-3f; - B2_NOT_USED(k_errorTol); - - for (;;) - { - // - // Case 1: vn = 0 - // - // 0 = A * x + b' - // - // Solve for x: - // - // x = - inv(A) * b' - // - b2Vec2 x = - b2Mul(vc->normalMass, b); - - if (x.x >= 0.0f && x.y >= 0.0f) - { - // Get the incremental impulse - b2Vec2 d = x - a; - - // Apply incremental impulse - b2Vec2 P1 = d.x * normal; - b2Vec2 P2 = d.y * normal; - vA -= mA * (P1 + P2); - wA -= iA * (b2Cross(cp1->rA, P1) + b2Cross(cp2->rA, P2)); - - vB += mB * (P1 + P2); - wB += iB * (b2Cross(cp1->rB, P1) + b2Cross(cp2->rB, P2)); - - // Accumulate - cp1->normalImpulse = x.x; - cp2->normalImpulse = x.y; - -#if B2_DEBUG_SOLVER == 1 - // Postconditions - dv1 = vB + b2Cross(wB, cp1->rB) - vA - b2Cross(wA, cp1->rA); - dv2 = vB + b2Cross(wB, cp2->rB) - vA - b2Cross(wA, cp2->rA); - - // Compute normal velocity - vn1 = b2Dot(dv1, normal); - vn2 = b2Dot(dv2, normal); - - b2Assert(b2Abs(vn1 - cp1->velocityBias) < k_errorTol); - b2Assert(b2Abs(vn2 - cp2->velocityBias) < k_errorTol); -#endif - break; - } - - // - // Case 2: vn1 = 0 and x2 = 0 - // - // 0 = a11 * x1 + a12 * 0 + b1' - // vn2 = a21 * x1 + a22 * 0 + b2' - // - x.x = - cp1->normalMass * b.x; - x.y = 0.0f; - vn1 = 0.0f; - vn2 = vc->K.ex.y * x.x + b.y; - if (x.x >= 0.0f && vn2 >= 0.0f) - { - // Get the incremental impulse - b2Vec2 d = x - a; - - // Apply incremental impulse - b2Vec2 P1 = d.x * normal; - b2Vec2 P2 = d.y * normal; - vA -= mA * (P1 + P2); - wA -= iA * (b2Cross(cp1->rA, P1) + b2Cross(cp2->rA, P2)); - - vB += mB * (P1 + P2); - wB += iB * (b2Cross(cp1->rB, P1) + b2Cross(cp2->rB, P2)); - - // Accumulate - cp1->normalImpulse = x.x; - cp2->normalImpulse = x.y; - -#if B2_DEBUG_SOLVER == 1 - // Postconditions - dv1 = vB + b2Cross(wB, cp1->rB) - vA - b2Cross(wA, cp1->rA); - - // Compute normal velocity - vn1 = b2Dot(dv1, normal); - - b2Assert(b2Abs(vn1 - cp1->velocityBias) < k_errorTol); -#endif - break; - } - - - // - // Case 3: vn2 = 0 and x1 = 0 - // - // vn1 = a11 * 0 + a12 * x2 + b1' - // 0 = a21 * 0 + a22 * x2 + b2' - // - x.x = 0.0f; - x.y = - cp2->normalMass * b.y; - vn1 = vc->K.ey.x * x.y + b.x; - vn2 = 0.0f; - - if (x.y >= 0.0f && vn1 >= 0.0f) - { - // Resubstitute for the incremental impulse - b2Vec2 d = x - a; - - // Apply incremental impulse - b2Vec2 P1 = d.x * normal; - b2Vec2 P2 = d.y * normal; - vA -= mA * (P1 + P2); - wA -= iA * (b2Cross(cp1->rA, P1) + b2Cross(cp2->rA, P2)); - - vB += mB * (P1 + P2); - wB += iB * (b2Cross(cp1->rB, P1) + b2Cross(cp2->rB, P2)); - - // Accumulate - cp1->normalImpulse = x.x; - cp2->normalImpulse = x.y; - -#if B2_DEBUG_SOLVER == 1 - // Postconditions - dv2 = vB + b2Cross(wB, cp2->rB) - vA - b2Cross(wA, cp2->rA); - - // Compute normal velocity - vn2 = b2Dot(dv2, normal); - - b2Assert(b2Abs(vn2 - cp2->velocityBias) < k_errorTol); -#endif - break; - } - - // - // Case 4: x1 = 0 and x2 = 0 - // - // vn1 = b1 - // vn2 = b2; - x.x = 0.0f; - x.y = 0.0f; - vn1 = b.x; - vn2 = b.y; - - if (vn1 >= 0.0f && vn2 >= 0.0f ) - { - // Resubstitute for the incremental impulse - b2Vec2 d = x - a; - - // Apply incremental impulse - b2Vec2 P1 = d.x * normal; - b2Vec2 P2 = d.y * normal; - vA -= mA * (P1 + P2); - wA -= iA * (b2Cross(cp1->rA, P1) + b2Cross(cp2->rA, P2)); - - vB += mB * (P1 + P2); - wB += iB * (b2Cross(cp1->rB, P1) + b2Cross(cp2->rB, P2)); - - // Accumulate - cp1->normalImpulse = x.x; - cp2->normalImpulse = x.y; - - break; - } - - // No solution, give up. This is hit sometimes, but it doesn't seem to matter. - break; - } - } - - m_velocities[indexA].v = vA; - m_velocities[indexA].w = wA; - m_velocities[indexB].v = vB; - m_velocities[indexB].w = wB; - } -} - -void b2ContactSolver::StoreImpulses() -{ - for (int32 i = 0; i < m_count; ++i) - { - b2ContactVelocityConstraint* vc = m_velocityConstraints + i; - b2Manifold* manifold = m_contacts[vc->contactIndex]->GetManifold(); - - for (int32 j = 0; j < vc->pointCount; ++j) - { - manifold->points[j].normalImpulse = vc->points[j].normalImpulse; - manifold->points[j].tangentImpulse = vc->points[j].tangentImpulse; - } - } -} - -struct b2PositionSolverManifold -{ - void Initialize(b2ContactPositionConstraint* pc, const b2Transform& xfA, const b2Transform& xfB, int32 index) - { - b2Assert(pc->pointCount > 0); - - switch (pc->type) - { - case b2Manifold::e_circles: - { - b2Vec2 pointA = b2Mul(xfA, pc->localPoint); - b2Vec2 pointB = b2Mul(xfB, pc->localPoints[0]); - normal = pointB - pointA; - normal.Normalize(); - point = 0.5f * (pointA + pointB); - separation = b2Dot(pointB - pointA, normal) - pc->radiusA - pc->radiusB; - } - break; - - case b2Manifold::e_faceA: - { - normal = b2Mul(xfA.q, pc->localNormal); - b2Vec2 planePoint = b2Mul(xfA, pc->localPoint); - - b2Vec2 clipPoint = b2Mul(xfB, pc->localPoints[index]); - separation = b2Dot(clipPoint - planePoint, normal) - pc->radiusA - pc->radiusB; - point = clipPoint; - } - break; - - case b2Manifold::e_faceB: - { - normal = b2Mul(xfB.q, pc->localNormal); - b2Vec2 planePoint = b2Mul(xfB, pc->localPoint); - - b2Vec2 clipPoint = b2Mul(xfA, pc->localPoints[index]); - separation = b2Dot(clipPoint - planePoint, normal) - pc->radiusA - pc->radiusB; - point = clipPoint; - - // Ensure normal points from A to B - normal = -normal; - } - break; - } - } - - b2Vec2 normal; - b2Vec2 point; - float32 separation; -}; - -// Sequential solver. -bool b2ContactSolver::SolvePositionConstraints() -{ - float32 minSeparation = 0.0f; - - for (int32 i = 0; i < m_count; ++i) - { - b2ContactPositionConstraint* pc = m_positionConstraints + i; - - int32 indexA = pc->indexA; - int32 indexB = pc->indexB; - b2Vec2 localCenterA = pc->localCenterA; - float32 mA = pc->invMassA; - float32 iA = pc->invIA; - b2Vec2 localCenterB = pc->localCenterB; - float32 mB = pc->invMassB; - float32 iB = pc->invIB; - int32 pointCount = pc->pointCount; - - b2Vec2 cA = m_positions[indexA].c; - float32 aA = m_positions[indexA].a; - - b2Vec2 cB = m_positions[indexB].c; - float32 aB = m_positions[indexB].a; - - // Solve normal constraints - for (int32 j = 0; j < pointCount; ++j) - { - b2Transform xfA, xfB; - xfA.q.Set(aA); - xfB.q.Set(aB); - xfA.p = cA - b2Mul(xfA.q, localCenterA); - xfB.p = cB - b2Mul(xfB.q, localCenterB); - - b2PositionSolverManifold psm; - psm.Initialize(pc, xfA, xfB, j); - b2Vec2 normal = psm.normal; - - b2Vec2 point = psm.point; - float32 separation = psm.separation; - - b2Vec2 rA = point - cA; - b2Vec2 rB = point - cB; - - // Track max constraint error. - minSeparation = b2Min(minSeparation, separation); - - // Prevent large corrections and allow slop. - float32 C = b2Clamp(b2_baumgarte * (separation + b2_linearSlop), -b2_maxLinearCorrection, 0.0f); - - // Compute the effective mass. - float32 rnA = b2Cross(rA, normal); - float32 rnB = b2Cross(rB, normal); - float32 K = mA + mB + iA * rnA * rnA + iB * rnB * rnB; - - // Compute normal impulse - float32 impulse = K > 0.0f ? - C / K : 0.0f; - - b2Vec2 P = impulse * normal; - - cA -= mA * P; - aA -= iA * b2Cross(rA, P); - - cB += mB * P; - aB += iB * b2Cross(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 >= -b2_linearSlop because we don't - // push the separation above -b2_linearSlop. - return minSeparation >= -3.0f * b2_linearSlop; -} - -// Sequential position solver for position constraints. -bool b2ContactSolver::SolveTOIPositionConstraints(int32 toiIndexA, int32 toiIndexB) -{ - float32 minSeparation = 0.0f; - - for (int32 i = 0; i < m_count; ++i) - { - b2ContactPositionConstraint* pc = m_positionConstraints + i; - - int32 indexA = pc->indexA; - int32 indexB = pc->indexB; - b2Vec2 localCenterA = pc->localCenterA; - b2Vec2 localCenterB = pc->localCenterB; - int32 pointCount = pc->pointCount; - - float32 mA = 0.0f; - float32 iA = 0.0f; - if (indexA == toiIndexA || indexA == toiIndexB) - { - mA = pc->invMassA; - iA = pc->invIA; - } - - float32 mB = 0.0f; - float32 iB = 0.; - if (indexB == toiIndexA || indexB == toiIndexB) - { - mB = pc->invMassB; - iB = pc->invIB; - } - - b2Vec2 cA = m_positions[indexA].c; - float32 aA = m_positions[indexA].a; - - b2Vec2 cB = m_positions[indexB].c; - float32 aB = m_positions[indexB].a; - - // Solve normal constraints - for (int32 j = 0; j < pointCount; ++j) - { - b2Transform xfA, xfB; - xfA.q.Set(aA); - xfB.q.Set(aB); - xfA.p = cA - b2Mul(xfA.q, localCenterA); - xfB.p = cB - b2Mul(xfB.q, localCenterB); - - b2PositionSolverManifold psm; - psm.Initialize(pc, xfA, xfB, j); - b2Vec2 normal = psm.normal; - - b2Vec2 point = psm.point; - float32 separation = psm.separation; - - b2Vec2 rA = point - cA; - b2Vec2 rB = point - cB; - - // Track max constraint error. - minSeparation = b2Min(minSeparation, separation); - - // Prevent large corrections and allow slop. - float32 C = b2Clamp(b2_toiBaugarte * (separation + b2_linearSlop), -b2_maxLinearCorrection, 0.0f); - - // Compute the effective mass. - float32 rnA = b2Cross(rA, normal); - float32 rnB = b2Cross(rB, normal); - float32 K = mA + mB + iA * rnA * rnA + iB * rnB * rnB; - - // Compute normal impulse - float32 impulse = K > 0.0f ? - C / K : 0.0f; - - b2Vec2 P = impulse * normal; - - cA -= mA * P; - aA -= iA * b2Cross(rA, P); - - cB += mB * P; - aB += iB * b2Cross(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 >= -b2_linearSlop because we don't - // push the separation above -b2_linearSlop. - return minSeparation >= -1.5f * b2_linearSlop; -} |