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authorchai <chaifix@163.com>2019-03-19 23:06:27 +0800
committerchai <chaifix@163.com>2019-03-19 23:06:27 +0800
commit1497dccd63a84b7ee2b229b1ad9c5c02718f2a78 (patch)
treef8d1bff50da13e126d08c7345653e002e293202d /Source/3rdParty/Box2D/Dynamics/Contacts/b2ContactSolver.cpp
parent5e2a973516e0729b225da9de0b03015dc5854ac4 (diff)
*rename
Diffstat (limited to 'Source/3rdParty/Box2D/Dynamics/Contacts/b2ContactSolver.cpp')
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diff --git a/Source/3rdParty/Box2D/Dynamics/Contacts/b2ContactSolver.cpp b/Source/3rdParty/Box2D/Dynamics/Contacts/b2ContactSolver.cpp
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-/*
-* 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;
-}