/********************************************************************************
* ReactPhysics3D physics library, http://www.reactphysics3d.com *
* Copyright (c) 2010-2016 Daniel Chappuis *
*********************************************************************************
* *
* 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. *
* *
********************************************************************************/
// Libraries
#include "ContactSolver.h"
#include "DynamicsWorld.h"
#include "body/RigidBody.h"
#include "utils/Profiler.h"
#include <limits>
using namespace reactphysics3d;
using namespace std;
// Constants initialization
const decimal ContactSolver::BETA = decimal(0.2);
const decimal ContactSolver::BETA_SPLIT_IMPULSE = decimal(0.2);
const decimal ContactSolver::SLOP = decimal(0.01);
// Constructor
ContactSolver::ContactSolver(MemoryManager& memoryManager, const WorldSettings& worldSettings)
:mMemoryManager(memoryManager), mSplitLinearVelocities(nullptr),
mSplitAngularVelocities(nullptr), mContactConstraints(nullptr),
mLinearVelocities(nullptr), mAngularVelocities(nullptr),
mIsSplitImpulseActive(true), mWorldSettings(worldSettings) {
}
// Initialize the contact constraints
void ContactSolver::init(Island** islands, uint nbIslands, decimal timeStep) {
RP3D_PROFILE("ContactSolver::init()", mProfiler);
mTimeStep = timeStep;
// TODO : Try not to count manifolds and contact points here
uint nbContactManifolds = 0;
uint nbContactPoints = 0;
for (uint i = 0; i < nbIslands; i++) {
uint nbManifoldsInIsland = islands[i]->getNbContactManifolds();
nbContactManifolds += nbManifoldsInIsland;
for (uint j=0; j < nbManifoldsInIsland; j++) {
nbContactPoints += islands[i]->getContactManifolds()[j]->getNbContactPoints();
}
}
mNbContactManifolds = 0;
mNbContactPoints = 0;
mContactConstraints = nullptr;
mContactPoints = nullptr;
if (nbContactManifolds == 0 || nbContactPoints == 0) return;
// TODO : Count exactly the number of constraints to allocate here
mContactPoints = static_cast<ContactPointSolver*>(mMemoryManager.allocate(MemoryManager::AllocationType::Frame,
sizeof(ContactPointSolver) * nbContactPoints));
assert(mContactPoints != nullptr);
mContactConstraints = static_cast<ContactManifoldSolver*>(mMemoryManager.allocate(MemoryManager::AllocationType::Frame,
sizeof(ContactManifoldSolver) * nbContactManifolds));
assert(mContactConstraints != nullptr);
// For each island of the world
for (uint islandIndex = 0; islandIndex < nbIslands; islandIndex++) {
if (islands[islandIndex]->getNbContactManifolds() > 0) {
initializeForIsland(islands[islandIndex]);
}
}
// Warmstarting
warmStart();
}
// Initialize the constraint solver for a given island
void ContactSolver::initializeForIsland(Island* island) {
RP3D_PROFILE("ContactSolver::initializeForIsland()", mProfiler);
assert(island != nullptr);
assert(island->getNbBodies() > 0);
assert(island->getNbContactManifolds() > 0);
assert(mSplitLinearVelocities != nullptr);
assert(mSplitAngularVelocities != nullptr);
// For each contact manifold of the island
ContactManifold** contactManifolds = island->getContactManifolds();
for (uint i=0; i<island->getNbContactManifolds(); i++) {
ContactManifold* externalManifold = contactManifolds[i];
assert(externalManifold->getNbContactPoints() > 0);
// Get the two bodies of the contact
RigidBody* body1 = static_cast<RigidBody*>(externalManifold->getBody1());
RigidBody* body2 = static_cast<RigidBody*>(externalManifold->getBody2());
assert(body1 != nullptr);
assert(body2 != nullptr);
// Get the two contact shapes
const ProxyShape* shape1 = externalManifold->getShape1();
const ProxyShape* shape2 = externalManifold->getShape2();
// Get the position of the two bodies
const Vector3& x1 = body1->mCenterOfMassWorld;
const Vector3& x2 = body2->mCenterOfMassWorld;
// Initialize the internal contact manifold structure using the external
// contact manifold
new (mContactConstraints + mNbContactManifolds) ContactManifoldSolver();
mContactConstraints[mNbContactManifolds].indexBody1 = body1->mArrayIndex;
mContactConstraints[mNbContactManifolds].indexBody2 = body2->mArrayIndex;
mContactConstraints[mNbContactManifolds].inverseInertiaTensorBody1 = body1->getInertiaTensorInverseWorld();
mContactConstraints[mNbContactManifolds].inverseInertiaTensorBody2 = body2->getInertiaTensorInverseWorld();
mContactConstraints[mNbContactManifolds].massInverseBody1 = body1->mMassInverse;
mContactConstraints[mNbContactManifolds].massInverseBody2 = body2->mMassInverse;
mContactConstraints[mNbContactManifolds].nbContacts = externalManifold->getNbContactPoints();
mContactConstraints[mNbContactManifolds].frictionCoefficient = computeMixedFrictionCoefficient(body1, body2);
mContactConstraints[mNbContactManifolds].rollingResistanceFactor = computeMixedRollingResistance(body1, body2);
mContactConstraints[mNbContactManifolds].externalContactManifold = externalManifold;
mContactConstraints[mNbContactManifolds].normal.setToZero();
mContactConstraints[mNbContactManifolds].frictionPointBody1.setToZero();
mContactConstraints[mNbContactManifolds].frictionPointBody2.setToZero();
// Get the velocities of the bodies
const Vector3& v1 = mLinearVelocities[mContactConstraints[mNbContactManifolds].indexBody1];
const Vector3& w1 = mAngularVelocities[mContactConstraints[mNbContactManifolds].indexBody1];
const Vector3& v2 = mLinearVelocities[mContactConstraints[mNbContactManifolds].indexBody2];
const Vector3& w2 = mAngularVelocities[mContactConstraints[mNbContactManifolds].indexBody2];
// For each contact point of the contact manifold
ContactPoint* externalContact = externalManifold->getContactPoints();
assert(externalContact != nullptr);
while (externalContact != nullptr) {
// Get the contact point on the two bodies
Vector3 p1 = shape1->getLocalToWorldTransform() * externalContact->getLocalPointOnShape1();
Vector3 p2 = shape2->getLocalToWorldTransform() * externalContact->getLocalPointOnShape2();
new (mContactPoints + mNbContactPoints) ContactPointSolver();
mContactPoints[mNbContactPoints].externalContact = externalContact;
mContactPoints[mNbContactPoints].normal = externalContact->getNormal();
mContactPoints[mNbContactPoints].r1.x = p1.x - x1.x;
mContactPoints[mNbContactPoints].r1.y = p1.y - x1.y;
mContactPoints[mNbContactPoints].r1.z = p1.z - x1.z;
mContactPoints[mNbContactPoints].r2.x = p2.x - x2.x;
mContactPoints[mNbContactPoints].r2.y = p2.y - x2.y;
mContactPoints[mNbContactPoints].r2.z = p2.z - x2.z;
mContactPoints[mNbContactPoints].penetrationDepth = externalContact->getPenetrationDepth();
mContactPoints[mNbContactPoints].isRestingContact = externalContact->getIsRestingContact();
externalContact->setIsRestingContact(true);
mContactPoints[mNbContactPoints].penetrationImpulse = externalContact->getPenetrationImpulse();
mContactPoints[mNbContactPoints].penetrationSplitImpulse = 0.0;
mContactConstraints[mNbContactManifolds].frictionPointBody1.x += p1.x;
mContactConstraints[mNbContactManifolds].frictionPointBody1.y += p1.y;
mContactConstraints[mNbContactManifolds].frictionPointBody1.z += p1.z;
mContactConstraints[mNbContactManifolds].frictionPointBody2.x += p2.x;
mContactConstraints[mNbContactManifolds].frictionPointBody2.y += p2.y;
mContactConstraints[mNbContactManifolds].frictionPointBody2.z += p2.z;
// Compute the velocity difference
//deltaV = v2 + w2.cross(mContactPoints[mNbContactPoints].r2) - v1 - w1.cross(mContactPoints[mNbContactPoints].r1);
Vector3 deltaV(v2.x + w2.y * mContactPoints[mNbContactPoints].r2.z - w2.z * mContactPoints[mNbContactPoints].r2.y
- v1.x - w1.y * mContactPoints[mNbContactPoints].r1.z - w1.z * mContactPoints[mNbContactPoints].r1.y,
v2.y + w2.z * mContactPoints[mNbContactPoints].r2.x - w2.x * mContactPoints[mNbContactPoints].r2.z
- v1.y - w1.z * mContactPoints[mNbContactPoints].r1.x - w1.x * mContactPoints[mNbContactPoints].r1.z,
v2.z + w2.x * mContactPoints[mNbContactPoints].r2.y - w2.y * mContactPoints[mNbContactPoints].r2.x
- v1.z - w1.x * mContactPoints[mNbContactPoints].r1.y - w1.y * mContactPoints[mNbContactPoints].r1.x);
// r1CrossN = mContactPoints[mNbContactPoints].r1.cross(mContactPoints[mNbContactPoints].normal);
Vector3 r1CrossN(mContactPoints[mNbContactPoints].r1.y * mContactPoints[mNbContactPoints].normal.z -
mContactPoints[mNbContactPoints].r1.z * mContactPoints[mNbContactPoints].normal.y,
mContactPoints[mNbContactPoints].r1.z * mContactPoints[mNbContactPoints].normal.x -
mContactPoints[mNbContactPoints].r1.x * mContactPoints[mNbContactPoints].normal.z,
mContactPoints[mNbContactPoints].r1.x * mContactPoints[mNbContactPoints].normal.y -
mContactPoints[mNbContactPoints].r1.y * mContactPoints[mNbContactPoints].normal.x);
// r2CrossN = mContactPoints[mNbContactPoints].r2.cross(mContactPoints[mNbContactPoints].normal);
Vector3 r2CrossN(mContactPoints[mNbContactPoints].r2.y * mContactPoints[mNbContactPoints].normal.z -
mContactPoints[mNbContactPoints].r2.z * mContactPoints[mNbContactPoints].normal.y,
mContactPoints[mNbContactPoints].r2.z * mContactPoints[mNbContactPoints].normal.x -
mContactPoints[mNbContactPoints].r2.x * mContactPoints[mNbContactPoints].normal.z,
mContactPoints[mNbContactPoints].r2.x * mContactPoints[mNbContactPoints].normal.y -
mContactPoints[mNbContactPoints].r2.y * mContactPoints[mNbContactPoints].normal.x);
mContactPoints[mNbContactPoints].i1TimesR1CrossN = mContactConstraints[mNbContactManifolds].inverseInertiaTensorBody1 * r1CrossN;
mContactPoints[mNbContactPoints].i2TimesR2CrossN = mContactConstraints[mNbContactManifolds].inverseInertiaTensorBody2 * r2CrossN;
// Compute the inverse mass matrix K for the penetration constraint
decimal massPenetration = mContactConstraints[mNbContactManifolds].massInverseBody1 + mContactConstraints[mNbContactManifolds].massInverseBody2 +
((mContactPoints[mNbContactPoints].i1TimesR1CrossN).cross(mContactPoints[mNbContactPoints].r1)).dot(mContactPoints[mNbContactPoints].normal) +
((mContactPoints[mNbContactPoints].i2TimesR2CrossN).cross(mContactPoints[mNbContactPoints].r2)).dot(mContactPoints[mNbContactPoints].normal);
mContactPoints[mNbContactPoints].inversePenetrationMass = massPenetration > decimal(0.0) ? decimal(1.0) / massPenetration : decimal(0.0);
// Compute the restitution velocity bias "b". We compute this here instead
// of inside the solve() method because we need to use the velocity difference
// at the beginning of the contact. Note that if it is a resting contact (normal
// velocity bellow a given threshold), we do not add a restitution velocity bias
mContactPoints[mNbContactPoints].restitutionBias = 0.0;
// deltaVDotN = deltaV.dot(mContactPoints[mNbContactPoints].normal);
decimal deltaVDotN = deltaV.x * mContactPoints[mNbContactPoints].normal.x +
deltaV.y * mContactPoints[mNbContactPoints].normal.y +
deltaV.z * mContactPoints[mNbContactPoints].normal.z;
const decimal restitutionFactor = computeMixedRestitutionFactor(body1, body2);
if (deltaVDotN < -mWorldSettings.restitutionVelocityThreshold) {
mContactPoints[mNbContactPoints].restitutionBias = restitutionFactor * deltaVDotN;
}
mContactConstraints[mNbContactManifolds].normal.x += mContactPoints[mNbContactPoints].normal.x;
mContactConstraints[mNbContactManifolds].normal.y += mContactPoints[mNbContactPoints].normal.y;
mContactConstraints[mNbContactManifolds].normal.z += mContactPoints[mNbContactPoints].normal.z;
mNbContactPoints++;
externalContact = externalContact->getNext();
}
mContactConstraints[mNbContactManifolds].frictionPointBody1 /=static_cast<decimal>(mContactConstraints[mNbContactManifolds].nbContacts);
mContactConstraints[mNbContactManifolds].frictionPointBody2 /=static_cast<decimal>(mContactConstraints[mNbContactManifolds].nbContacts);
mContactConstraints[mNbContactManifolds].r1Friction.x = mContactConstraints[mNbContactManifolds].frictionPointBody1.x - x1.x;
mContactConstraints[mNbContactManifolds].r1Friction.y = mContactConstraints[mNbContactManifolds].frictionPointBody1.y - x1.y;
mContactConstraints[mNbContactManifolds].r1Friction.z = mContactConstraints[mNbContactManifolds].frictionPointBody1.z - x1.z;
mContactConstraints[mNbContactManifolds].r2Friction.x = mContactConstraints[mNbContactManifolds].frictionPointBody2.x - x2.x;
mContactConstraints[mNbContactManifolds].r2Friction.y = mContactConstraints[mNbContactManifolds].frictionPointBody2.y - x2.y;
mContactConstraints[mNbContactManifolds].r2Friction.z = mContactConstraints[mNbContactManifolds].frictionPointBody2.z - x2.z;
mContactConstraints[mNbContactManifolds].oldFrictionVector1 = externalManifold->getFrictionVector1();
mContactConstraints[mNbContactManifolds].oldFrictionVector2 = externalManifold->getFrictionVector2();
// Initialize the accumulated impulses with the previous step accumulated impulses
mContactConstraints[mNbContactManifolds].friction1Impulse = externalManifold->getFrictionImpulse1();
mContactConstraints[mNbContactManifolds].friction2Impulse = externalManifold->getFrictionImpulse2();
mContactConstraints[mNbContactManifolds].frictionTwistImpulse = externalManifold->getFrictionTwistImpulse();
// Compute the inverse K matrix for the rolling resistance constraint
bool isBody1DynamicType = body1->getType() == BodyType::DYNAMIC;
bool isBody2DynamicType = body2->getType() == BodyType::DYNAMIC;
mContactConstraints[mNbContactManifolds].inverseRollingResistance.setToZero();
if (mContactConstraints[mNbContactManifolds].rollingResistanceFactor > 0 && (isBody1DynamicType || isBody2DynamicType)) {
mContactConstraints[mNbContactManifolds].inverseRollingResistance = mContactConstraints[mNbContactManifolds].inverseInertiaTensorBody1 + mContactConstraints[mNbContactManifolds].inverseInertiaTensorBody2;
decimal det = mContactConstraints[mNbContactManifolds].inverseRollingResistance.getDeterminant();
// If the matrix is not inversible
if (approxEqual(det, decimal(0.0))) {
mContactConstraints[mNbContactManifolds].inverseRollingResistance.setToZero();
}
else {
mContactConstraints[mNbContactManifolds].inverseRollingResistance = mContactConstraints[mNbContactManifolds].inverseRollingResistance.getInverse();
}
}
mContactConstraints[mNbContactManifolds].normal.normalize();
// deltaVFrictionPoint = v2 + w2.cross(mContactConstraints[mNbContactManifolds].r2Friction) -
// v1 - w1.cross(mContactConstraints[mNbContactManifolds].r1Friction);
Vector3 deltaVFrictionPoint(v2.x + w2.y * mContactConstraints[mNbContactManifolds].r2Friction.z -
w2.z * mContactConstraints[mNbContactManifolds].r2Friction.y -
v1.x - w1.y * mContactConstraints[mNbContactManifolds].r1Friction.z -
w1.z * mContactConstraints[mNbContactManifolds].r1Friction.y,
v2.y + w2.z * mContactConstraints[mNbContactManifolds].r2Friction.x -
w2.x * mContactConstraints[mNbContactManifolds].r2Friction.z -
v1.y - w1.z * mContactConstraints[mNbContactManifolds].r1Friction.x -
w1.x * mContactConstraints[mNbContactManifolds].r1Friction.z,
v2.z + w2.x * mContactConstraints[mNbContactManifolds].r2Friction.y -
w2.y * mContactConstraints[mNbContactManifolds].r2Friction.x -
v1.z - w1.x * mContactConstraints[mNbContactManifolds].r1Friction.y -
w1.y * mContactConstraints[mNbContactManifolds].r1Friction.x);
// Compute the friction vectors
computeFrictionVectors(deltaVFrictionPoint, mContactConstraints[mNbContactManifolds]);
// Compute the inverse mass matrix K for the friction constraints at the center of
// the contact manifold
mContactConstraints[mNbContactManifolds].r1CrossT1 = mContactConstraints[mNbContactManifolds].r1Friction.cross(mContactConstraints[mNbContactManifolds].frictionVector1);
mContactConstraints[mNbContactManifolds].r1CrossT2 = mContactConstraints[mNbContactManifolds].r1Friction.cross(mContactConstraints[mNbContactManifolds].frictionVector2);
mContactConstraints[mNbContactManifolds].r2CrossT1 = mContactConstraints[mNbContactManifolds].r2Friction.cross(mContactConstraints[mNbContactManifolds].frictionVector1);
mContactConstraints[mNbContactManifolds].r2CrossT2 = mContactConstraints[mNbContactManifolds].r2Friction.cross(mContactConstraints[mNbContactManifolds].frictionVector2);
decimal friction1Mass = mContactConstraints[mNbContactManifolds].massInverseBody1 + mContactConstraints[mNbContactManifolds].massInverseBody2 +
((mContactConstraints[mNbContactManifolds].inverseInertiaTensorBody1 * mContactConstraints[mNbContactManifolds].r1CrossT1).cross(mContactConstraints[mNbContactManifolds].r1Friction)).dot(
mContactConstraints[mNbContactManifolds].frictionVector1) +
((mContactConstraints[mNbContactManifolds].inverseInertiaTensorBody2 * mContactConstraints[mNbContactManifolds].r2CrossT1).cross(mContactConstraints[mNbContactManifolds].r2Friction)).dot(
mContactConstraints[mNbContactManifolds].frictionVector1);
decimal friction2Mass = mContactConstraints[mNbContactManifolds].massInverseBody1 + mContactConstraints[mNbContactManifolds].massInverseBody2 +
((mContactConstraints[mNbContactManifolds].inverseInertiaTensorBody1 * mContactConstraints[mNbContactManifolds].r1CrossT2).cross(mContactConstraints[mNbContactManifolds].r1Friction)).dot(
mContactConstraints[mNbContactManifolds].frictionVector2) +
((mContactConstraints[mNbContactManifolds].inverseInertiaTensorBody2 * mContactConstraints[mNbContactManifolds].r2CrossT2).cross(mContactConstraints[mNbContactManifolds].r2Friction)).dot(
mContactConstraints[mNbContactManifolds].frictionVector2);
decimal frictionTwistMass = mContactConstraints[mNbContactManifolds].normal.dot(mContactConstraints[mNbContactManifolds].inverseInertiaTensorBody1 *
mContactConstraints[mNbContactManifolds].normal) +
mContactConstraints[mNbContactManifolds].normal.dot(mContactConstraints[mNbContactManifolds].inverseInertiaTensorBody2 *
mContactConstraints[mNbContactManifolds].normal);
mContactConstraints[mNbContactManifolds].inverseFriction1Mass = friction1Mass > decimal(0.0) ? decimal(1.0) / friction1Mass : decimal(0.0);
mContactConstraints[mNbContactManifolds].inverseFriction2Mass = friction2Mass > decimal(0.0) ? decimal(1.0) / friction2Mass : decimal(0.0);
mContactConstraints[mNbContactManifolds].inverseTwistFrictionMass = frictionTwistMass > decimal(0.0) ? decimal(1.0) / frictionTwistMass : decimal(0.0);
mNbContactManifolds++;
}
}
// Warm start the solver.
/// For each constraint, we apply the previous impulse (from the previous step)
/// at the beginning. With this technique, we will converge faster towards
/// the solution of the linear system
void ContactSolver::warmStart() {
RP3D_PROFILE("ContactSolver::warmStart()", mProfiler);
uint contactPointIndex = 0;
// For each constraint
for (uint c=0; c<mNbContactManifolds; c++) {
bool atLeastOneRestingContactPoint = false;
for (short int i=0; i<mContactConstraints[c].nbContacts; i++) {
// If it is not a new contact (this contact was already existing at last time step)
if (mContactPoints[contactPointIndex].isRestingContact) {
atLeastOneRestingContactPoint = true;
// --------- Penetration --------- //
// Update the velocities of the body 1 by applying the impulse P
Vector3 impulsePenetration(mContactPoints[contactPointIndex].normal.x * mContactPoints[contactPointIndex].penetrationImpulse,
mContactPoints[contactPointIndex].normal.y * mContactPoints[contactPointIndex].penetrationImpulse,
mContactPoints[contactPointIndex].normal.z * mContactPoints[contactPointIndex].penetrationImpulse);
mLinearVelocities[mContactConstraints[c].indexBody1].x -= mContactConstraints[c].massInverseBody1 * impulsePenetration.x;
mLinearVelocities[mContactConstraints[c].indexBody1].y -= mContactConstraints[c].massInverseBody1 * impulsePenetration.y;
mLinearVelocities[mContactConstraints[c].indexBody1].z -= mContactConstraints[c].massInverseBody1 * impulsePenetration.z;
mAngularVelocities[mContactConstraints[c].indexBody1].x -= mContactPoints[contactPointIndex].i1TimesR1CrossN.x * mContactPoints[contactPointIndex].penetrationImpulse;
mAngularVelocities[mContactConstraints[c].indexBody1].y -= mContactPoints[contactPointIndex].i1TimesR1CrossN.y * mContactPoints[contactPointIndex].penetrationImpulse;
mAngularVelocities[mContactConstraints[c].indexBody1].z -= mContactPoints[contactPointIndex].i1TimesR1CrossN.z * mContactPoints[contactPointIndex].penetrationImpulse;
// Update the velocities of the body 2 by applying the impulse P
mLinearVelocities[mContactConstraints[c].indexBody2].x += mContactConstraints[c].massInverseBody2 * impulsePenetration.x;
mLinearVelocities[mContactConstraints[c].indexBody2].y += mContactConstraints[c].massInverseBody2 * impulsePenetration.y;
mLinearVelocities[mContactConstraints[c].indexBody2].z += mContactConstraints[c].massInverseBody2 * impulsePenetration.z;
mAngularVelocities[mContactConstraints[c].indexBody2].x += mContactPoints[contactPointIndex].i2TimesR2CrossN.x * mContactPoints[contactPointIndex].penetrationImpulse;
mAngularVelocities[mContactConstraints[c].indexBody2].y += mContactPoints[contactPointIndex].i2TimesR2CrossN.y * mContactPoints[contactPointIndex].penetrationImpulse;
mAngularVelocities[mContactConstraints[c].indexBody2].z += mContactPoints[contactPointIndex].i2TimesR2CrossN.z * mContactPoints[contactPointIndex].penetrationImpulse;
}
else { // If it is a new contact point
// Initialize the accumulated impulses to zero
mContactPoints[contactPointIndex].penetrationImpulse = 0.0;
}
contactPointIndex++;
}
// If we solve the friction constraints at the center of the contact manifold and there is
// at least one resting contact point in the contact manifold
if (atLeastOneRestingContactPoint) {
// Project the old friction impulses (with old friction vectors) into the new friction
// vectors to get the new friction impulses
Vector3 oldFrictionImpulse(mContactConstraints[c].friction1Impulse * mContactConstraints[c].oldFrictionVector1.x +
mContactConstraints[c].friction2Impulse * mContactConstraints[c].oldFrictionVector2.x,
mContactConstraints[c].friction1Impulse * mContactConstraints[c].oldFrictionVector1.y +
mContactConstraints[c].friction2Impulse * mContactConstraints[c].oldFrictionVector2.y,
mContactConstraints[c].friction1Impulse * mContactConstraints[c].oldFrictionVector1.z +
mContactConstraints[c].friction2Impulse * mContactConstraints[c].oldFrictionVector2.z);
mContactConstraints[c].friction1Impulse = oldFrictionImpulse.dot(mContactConstraints[c].frictionVector1);
mContactConstraints[c].friction2Impulse = oldFrictionImpulse.dot(mContactConstraints[c].frictionVector2);
// ------ First friction constraint at the center of the contact manifold ------ //
// Compute the impulse P = J^T * lambda
Vector3 angularImpulseBody1(-mContactConstraints[c].r1CrossT1.x * mContactConstraints[c].friction1Impulse,
-mContactConstraints[c].r1CrossT1.y * mContactConstraints[c].friction1Impulse,
-mContactConstraints[c].r1CrossT1.z * mContactConstraints[c].friction1Impulse);
Vector3 linearImpulseBody2(mContactConstraints[c].frictionVector1.x * mContactConstraints[c].friction1Impulse,
mContactConstraints[c].frictionVector1.y * mContactConstraints[c].friction1Impulse,
mContactConstraints[c].frictionVector1.z * mContactConstraints[c].friction1Impulse);
Vector3 angularImpulseBody2(mContactConstraints[c].r2CrossT1.x * mContactConstraints[c].friction1Impulse,
mContactConstraints[c].r2CrossT1.y * mContactConstraints[c].friction1Impulse,
mContactConstraints[c].r2CrossT1.z * mContactConstraints[c].friction1Impulse);
// Update the velocities of the body 1 by applying the impulse P
mLinearVelocities[mContactConstraints[c].indexBody1] -= mContactConstraints[c].massInverseBody1 * linearImpulseBody2;
mAngularVelocities[mContactConstraints[c].indexBody1] += mContactConstraints[c].inverseInertiaTensorBody1 * angularImpulseBody1;
// Update the velocities of the body 1 by applying the impulse P
mLinearVelocities[mContactConstraints[c].indexBody2] += mContactConstraints[c].massInverseBody2 * linearImpulseBody2;
mAngularVelocities[mContactConstraints[c].indexBody2] += mContactConstraints[c].inverseInertiaTensorBody2 * angularImpulseBody2;
// ------ Second friction constraint at the center of the contact manifold ----- //
// Compute the impulse P = J^T * lambda
angularImpulseBody1.x = -mContactConstraints[c].r1CrossT2.x * mContactConstraints[c].friction2Impulse;
angularImpulseBody1.y = -mContactConstraints[c].r1CrossT2.y * mContactConstraints[c].friction2Impulse;
angularImpulseBody1.z = -mContactConstraints[c].r1CrossT2.z * mContactConstraints[c].friction2Impulse;
linearImpulseBody2.x = mContactConstraints[c].frictionVector2.x * mContactConstraints[c].friction2Impulse;
linearImpulseBody2.y = mContactConstraints[c].frictionVector2.y * mContactConstraints[c].friction2Impulse;
linearImpulseBody2.z = mContactConstraints[c].frictionVector2.z * mContactConstraints[c].friction2Impulse;
angularImpulseBody2.x = mContactConstraints[c].r2CrossT2.x * mContactConstraints[c].friction2Impulse;
angularImpulseBody2.y = mContactConstraints[c].r2CrossT2.y * mContactConstraints[c].friction2Impulse;
angularImpulseBody2.z = mContactConstraints[c].r2CrossT2.z * mContactConstraints[c].friction2Impulse;
// Update the velocities of the body 1 by applying the impulse P
mLinearVelocities[mContactConstraints[c].indexBody1].x -= mContactConstraints[c].massInverseBody1 * linearImpulseBody2.x;
mLinearVelocities[mContactConstraints[c].indexBody1].y -= mContactConstraints[c].massInverseBody1 * linearImpulseBody2.y;
mLinearVelocities[mContactConstraints[c].indexBody1].z -= mContactConstraints[c].massInverseBody1 * linearImpulseBody2.z;
mAngularVelocities[mContactConstraints[c].indexBody1] += mContactConstraints[c].inverseInertiaTensorBody1 * angularImpulseBody1;
// Update the velocities of the body 2 by applying the impulse P
mLinearVelocities[mContactConstraints[c].indexBody2].x += mContactConstraints[c].massInverseBody2 * linearImpulseBody2.x;
mLinearVelocities[mContactConstraints[c].indexBody2].y += mContactConstraints[c].massInverseBody2 * linearImpulseBody2.y;
mLinearVelocities[mContactConstraints[c].indexBody2].z += mContactConstraints[c].massInverseBody2 * linearImpulseBody2.z;
mAngularVelocities[mContactConstraints[c].indexBody2] += mContactConstraints[c].inverseInertiaTensorBody2 * angularImpulseBody2;
// ------ Twist friction constraint at the center of the contact manifold ------ //
// Compute the impulse P = J^T * lambda
angularImpulseBody1.x = -mContactConstraints[c].normal.x * mContactConstraints[c].frictionTwistImpulse;
angularImpulseBody1.y = -mContactConstraints[c].normal.y * mContactConstraints[c].frictionTwistImpulse;
angularImpulseBody1.z = -mContactConstraints[c].normal.z * mContactConstraints[c].frictionTwistImpulse;
angularImpulseBody2.x = mContactConstraints[c].normal.x * mContactConstraints[c].frictionTwistImpulse;
angularImpulseBody2.y = mContactConstraints[c].normal.y * mContactConstraints[c].frictionTwistImpulse;
angularImpulseBody2.z = mContactConstraints[c].normal.z * mContactConstraints[c].frictionTwistImpulse;
// Update the velocities of the body 1 by applying the impulse P
mAngularVelocities[mContactConstraints[c].indexBody1] += mContactConstraints[c].inverseInertiaTensorBody1 * angularImpulseBody1;
// Update the velocities of the body 2 by applying the impulse P
mAngularVelocities[mContactConstraints[c].indexBody2] += mContactConstraints[c].inverseInertiaTensorBody2 * angularImpulseBody2;
// ------ Rolling resistance at the center of the contact manifold ------ //
// Compute the impulse P = J^T * lambda
angularImpulseBody2 = mContactConstraints[c].rollingResistanceImpulse;
// Update the velocities of the body 1 by applying the impulse P
mAngularVelocities[mContactConstraints[c].indexBody1] -= mContactConstraints[c].inverseInertiaTensorBody1 * angularImpulseBody2;
// Update the velocities of the body 1 by applying the impulse P
mAngularVelocities[mContactConstraints[c].indexBody2] += mContactConstraints[c].inverseInertiaTensorBody2 * angularImpulseBody2;
}
else { // If it is a new contact manifold
// Initialize the accumulated impulses to zero
mContactConstraints[c].friction1Impulse = 0.0;
mContactConstraints[c].friction2Impulse = 0.0;
mContactConstraints[c].frictionTwistImpulse = 0.0;
mContactConstraints[c].rollingResistanceImpulse.setToZero();
}
}
}
// Solve the contacts
void ContactSolver::solve() {
RP3D_PROFILE("ContactSolver::solve()", mProfiler);
decimal deltaLambda;
decimal lambdaTemp;
uint contactPointIndex = 0;
// For each contact manifold
for (uint c=0; c<mNbContactManifolds; c++) {
decimal sumPenetrationImpulse = 0.0;
// Get the constrained velocities
const Vector3& v1 = mLinearVelocities[mContactConstraints[c].indexBody1];
const Vector3& w1 = mAngularVelocities[mContactConstraints[c].indexBody1];
const Vector3& v2 = mLinearVelocities[mContactConstraints[c].indexBody2];
const Vector3& w2 = mAngularVelocities[mContactConstraints[c].indexBody2];
for (short int i=0; i<mContactConstraints[c].nbContacts; i++) {
// --------- Penetration --------- //
// Compute J*v
//Vector3 deltaV = v2 + w2.cross(mContactPoints[contactPointIndex].r2) - v1 - w1.cross(mContactPoints[contactPointIndex].r1);
Vector3 deltaV(v2.x + w2.y * mContactPoints[contactPointIndex].r2.z - w2.z * mContactPoints[contactPointIndex].r2.y - v1.x -
w1.y * mContactPoints[contactPointIndex].r1.z + w1.z * mContactPoints[contactPointIndex].r1.y,
v2.y + w2.z * mContactPoints[contactPointIndex].r2.x - w2.x * mContactPoints[contactPointIndex].r2.z - v1.y -
w1.z * mContactPoints[contactPointIndex].r1.x + w1.x * mContactPoints[contactPointIndex].r1.z,
v2.z + w2.x * mContactPoints[contactPointIndex].r2.y - w2.y * mContactPoints[contactPointIndex].r2.x - v1.z -
w1.x * mContactPoints[contactPointIndex].r1.y + w1.y * mContactPoints[contactPointIndex].r1.x);
decimal deltaVDotN = deltaV.x * mContactPoints[contactPointIndex].normal.x + deltaV.y * mContactPoints[contactPointIndex].normal.y +
deltaV.z * mContactPoints[contactPointIndex].normal.z;
decimal Jv = deltaVDotN;
// Compute the bias "b" of the constraint
decimal beta = mIsSplitImpulseActive ? BETA_SPLIT_IMPULSE : BETA;
decimal biasPenetrationDepth = 0.0;
if (mContactPoints[contactPointIndex].penetrationDepth > SLOP) biasPenetrationDepth = -(beta/mTimeStep) *
max(0.0f, float(mContactPoints[contactPointIndex].penetrationDepth - SLOP));
decimal b = biasPenetrationDepth + mContactPoints[contactPointIndex].restitutionBias;
// Compute the Lagrange multiplier lambda
if (mIsSplitImpulseActive) {
deltaLambda = - (Jv + mContactPoints[contactPointIndex].restitutionBias) *
mContactPoints[contactPointIndex].inversePenetrationMass;
}
else {
deltaLambda = - (Jv + b) * mContactPoints[contactPointIndex].inversePenetrationMass;
}
lambdaTemp = mContactPoints[contactPointIndex].penetrationImpulse;
mContactPoints[contactPointIndex].penetrationImpulse = std::max(mContactPoints[contactPointIndex].penetrationImpulse +
deltaLambda, decimal(0.0));
deltaLambda = mContactPoints[contactPointIndex].penetrationImpulse - lambdaTemp;
Vector3 linearImpulse(mContactPoints[contactPointIndex].normal.x * deltaLambda,
mContactPoints[contactPointIndex].normal.y * deltaLambda,
mContactPoints[contactPointIndex].normal.z * deltaLambda);
// Update the velocities of the body 1 by applying the impulse P
mLinearVelocities[mContactConstraints[c].indexBody1].x -= mContactConstraints[c].massInverseBody1 * linearImpulse.x;
mLinearVelocities[mContactConstraints[c].indexBody1].y -= mContactConstraints[c].massInverseBody1 * linearImpulse.y;
mLinearVelocities[mContactConstraints[c].indexBody1].z -= mContactConstraints[c].massInverseBody1 * linearImpulse.z;
mAngularVelocities[mContactConstraints[c].indexBody1].x -= mContactPoints[contactPointIndex].i1TimesR1CrossN.x * deltaLambda;
mAngularVelocities[mContactConstraints[c].indexBody1].y -= mContactPoints[contactPointIndex].i1TimesR1CrossN.y * deltaLambda;
mAngularVelocities[mContactConstraints[c].indexBody1].z -= mContactPoints[contactPointIndex].i1TimesR1CrossN.z * deltaLambda;
// Update the velocities of the body 2 by applying the impulse P
mLinearVelocities[mContactConstraints[c].indexBody2].x += mContactConstraints[c].massInverseBody2 * linearImpulse.x;
mLinearVelocities[mContactConstraints[c].indexBody2].y += mContactConstraints[c].massInverseBody2 * linearImpulse.y;
mLinearVelocities[mContactConstraints[c].indexBody2].z += mContactConstraints[c].massInverseBody2 * linearImpulse.z;
mAngularVelocities[mContactConstraints[c].indexBody2].x += mContactPoints[contactPointIndex].i2TimesR2CrossN.x * deltaLambda;
mAngularVelocities[mContactConstraints[c].indexBody2].y += mContactPoints[contactPointIndex].i2TimesR2CrossN.y * deltaLambda;
mAngularVelocities[mContactConstraints[c].indexBody2].z += mContactPoints[contactPointIndex].i2TimesR2CrossN.z * deltaLambda;
sumPenetrationImpulse += mContactPoints[contactPointIndex].penetrationImpulse;
// If the split impulse position correction is active
if (mIsSplitImpulseActive) {
// Split impulse (position correction)
const Vector3& v1Split = mSplitLinearVelocities[mContactConstraints[c].indexBody1];
const Vector3& w1Split = mSplitAngularVelocities[mContactConstraints[c].indexBody1];
const Vector3& v2Split = mSplitLinearVelocities[mContactConstraints[c].indexBody2];
const Vector3& w2Split = mSplitAngularVelocities[mContactConstraints[c].indexBody2];
//Vector3 deltaVSplit = v2Split + w2Split.cross(mContactPoints[contactPointIndex].r2) - v1Split - w1Split.cross(mContactPoints[contactPointIndex].r1);
Vector3 deltaVSplit(v2Split.x + w2Split.y * mContactPoints[contactPointIndex].r2.z - w2Split.z * mContactPoints[contactPointIndex].r2.y - v1Split.x -
w1Split.y * mContactPoints[contactPointIndex].r1.z + w1Split.z * mContactPoints[contactPointIndex].r1.y,
v2Split.y + w2Split.z * mContactPoints[contactPointIndex].r2.x - w2Split.x * mContactPoints[contactPointIndex].r2.z - v1Split.y -
w1Split.z * mContactPoints[contactPointIndex].r1.x + w1Split.x * mContactPoints[contactPointIndex].r1.z,
v2Split.z + w2Split.x * mContactPoints[contactPointIndex].r2.y - w2Split.y * mContactPoints[contactPointIndex].r2.x - v1Split.z -
w1Split.x * mContactPoints[contactPointIndex].r1.y + w1Split.y * mContactPoints[contactPointIndex].r1.x);
decimal JvSplit = deltaVSplit.x * mContactPoints[contactPointIndex].normal.x +
deltaVSplit.y * mContactPoints[contactPointIndex].normal.y +
deltaVSplit.z * mContactPoints[contactPointIndex].normal.z;
decimal deltaLambdaSplit = - (JvSplit + biasPenetrationDepth) *
mContactPoints[contactPointIndex].inversePenetrationMass;
decimal lambdaTempSplit = mContactPoints[contactPointIndex].penetrationSplitImpulse;
mContactPoints[contactPointIndex].penetrationSplitImpulse = std::max(
mContactPoints[contactPointIndex].penetrationSplitImpulse +
deltaLambdaSplit, decimal(0.0));
deltaLambdaSplit = mContactPoints[contactPointIndex].penetrationSplitImpulse - lambdaTempSplit;
Vector3 linearImpulse(mContactPoints[contactPointIndex].normal.x * deltaLambdaSplit,
mContactPoints[contactPointIndex].normal.y * deltaLambdaSplit,
mContactPoints[contactPointIndex].normal.z * deltaLambdaSplit);
// Update the velocities of the body 1 by applying the impulse P
mSplitLinearVelocities[mContactConstraints[c].indexBody1].x -= mContactConstraints[c].massInverseBody1 * linearImpulse.x;
mSplitLinearVelocities[mContactConstraints[c].indexBody1].y -= mContactConstraints[c].massInverseBody1 * linearImpulse.y;
mSplitLinearVelocities[mContactConstraints[c].indexBody1].z -= mContactConstraints[c].massInverseBody1 * linearImpulse.z;
mSplitAngularVelocities[mContactConstraints[c].indexBody1].x -= mContactPoints[contactPointIndex].i1TimesR1CrossN.x * deltaLambdaSplit;
mSplitAngularVelocities[mContactConstraints[c].indexBody1].y -= mContactPoints[contactPointIndex].i1TimesR1CrossN.y * deltaLambdaSplit;
mSplitAngularVelocities[mContactConstraints[c].indexBody1].z -= mContactPoints[contactPointIndex].i1TimesR1CrossN.z * deltaLambdaSplit;
// Update the velocities of the body 1 by applying the impulse P
mSplitLinearVelocities[mContactConstraints[c].indexBody2].x += mContactConstraints[c].massInverseBody2 * linearImpulse.x;
mSplitLinearVelocities[mContactConstraints[c].indexBody2].y += mContactConstraints[c].massInverseBody2 * linearImpulse.y;
mSplitLinearVelocities[mContactConstraints[c].indexBody2].z += mContactConstraints[c].massInverseBody2 * linearImpulse.z;
mSplitAngularVelocities[mContactConstraints[c].indexBody2].x += mContactPoints[contactPointIndex].i2TimesR2CrossN.x * deltaLambdaSplit;
mSplitAngularVelocities[mContactConstraints[c].indexBody2].y += mContactPoints[contactPointIndex].i2TimesR2CrossN.y * deltaLambdaSplit;
mSplitAngularVelocities[mContactConstraints[c].indexBody2].z += mContactPoints[contactPointIndex].i2TimesR2CrossN.z * deltaLambdaSplit;
}
contactPointIndex++;
}
// ------ First friction constraint at the center of the contact manifol ------ //
// Compute J*v
// deltaV = v2 + w2.cross(mContactConstraints[c].r2Friction) - v1 - w1.cross(mContactConstraints[c].r1Friction);
Vector3 deltaV(v2.x + w2.y * mContactConstraints[c].r2Friction.z - w2.z * mContactConstraints[c].r2Friction.y - v1.x -
w1.y * mContactConstraints[c].r1Friction.z + w1.z * mContactConstraints[c].r1Friction.y,
v2.y + w2.z * mContactConstraints[c].r2Friction.x - w2.x * mContactConstraints[c].r2Friction.z - v1.y -
w1.z * mContactConstraints[c].r1Friction.x + w1.x * mContactConstraints[c].r1Friction.z,
v2.z + w2.x * mContactConstraints[c].r2Friction.y - w2.y * mContactConstraints[c].r2Friction.x - v1.z -
w1.x * mContactConstraints[c].r1Friction.y + w1.y * mContactConstraints[c].r1Friction.x);
decimal Jv = deltaV.x * mContactConstraints[c].frictionVector1.x +
deltaV.y * mContactConstraints[c].frictionVector1.y +
deltaV.z * mContactConstraints[c].frictionVector1.z;
// Compute the Lagrange multiplier lambda
decimal deltaLambda = -Jv * mContactConstraints[c].inverseFriction1Mass;
decimal frictionLimit = mContactConstraints[c].frictionCoefficient * sumPenetrationImpulse;
lambdaTemp = mContactConstraints[c].friction1Impulse;
mContactConstraints[c].friction1Impulse = std::max(-frictionLimit,
std::min(mContactConstraints[c].friction1Impulse +
deltaLambda, frictionLimit));
deltaLambda = mContactConstraints[c].friction1Impulse - lambdaTemp;
// Compute the impulse P=J^T * lambda
Vector3 angularImpulseBody1(-mContactConstraints[c].r1CrossT1.x * deltaLambda,
-mContactConstraints[c].r1CrossT1.y * deltaLambda,
-mContactConstraints[c].r1CrossT1.z * deltaLambda);
Vector3 linearImpulseBody2(mContactConstraints[c].frictionVector1.x * deltaLambda,
mContactConstraints[c].frictionVector1.y * deltaLambda,
mContactConstraints[c].frictionVector1.z * deltaLambda);
Vector3 angularImpulseBody2(mContactConstraints[c].r2CrossT1.x * deltaLambda,
mContactConstraints[c].r2CrossT1.y * deltaLambda,
mContactConstraints[c].r2CrossT1.z * deltaLambda);
// Update the velocities of the body 1 by applying the impulse P
mLinearVelocities[mContactConstraints[c].indexBody1].x -= mContactConstraints[c].massInverseBody1 * linearImpulseBody2.x;
mLinearVelocities[mContactConstraints[c].indexBody1].y -= mContactConstraints[c].massInverseBody1 * linearImpulseBody2.y;
mLinearVelocities[mContactConstraints[c].indexBody1].z -= mContactConstraints[c].massInverseBody1 * linearImpulseBody2.z;
mAngularVelocities[mContactConstraints[c].indexBody1] += mContactConstraints[c].inverseInertiaTensorBody1 * angularImpulseBody1;
// Update the velocities of the body 2 by applying the impulse P
mLinearVelocities[mContactConstraints[c].indexBody2].x += mContactConstraints[c].massInverseBody2 * linearImpulseBody2.x;
mLinearVelocities[mContactConstraints[c].indexBody2].y += mContactConstraints[c].massInverseBody2 * linearImpulseBody2.y;
mLinearVelocities[mContactConstraints[c].indexBody2].z += mContactConstraints[c].massInverseBody2 * linearImpulseBody2.z;
mAngularVelocities[mContactConstraints[c].indexBody2] += mContactConstraints[c].inverseInertiaTensorBody2 * angularImpulseBody2;
// ------ Second friction constraint at the center of the contact manifol ----- //
// Compute J*v
//deltaV = v2 + w2.cross(mContactConstraints[c].r2Friction) - v1 - w1.cross(mContactConstraints[c].r1Friction);
deltaV.x = v2.x + w2.y * mContactConstraints[c].r2Friction.z - v2.z * mContactConstraints[c].r2Friction.y - v1.x -
w1.y * mContactConstraints[c].r1Friction.z + w1.z * mContactConstraints[c].r1Friction.y;
deltaV.y = v2.y + w2.z * mContactConstraints[c].r2Friction.x - v2.x * mContactConstraints[c].r2Friction.z - v1.y -
w1.z * mContactConstraints[c].r1Friction.x + w1.x * mContactConstraints[c].r1Friction.z;
deltaV.z = v2.z + w2.x * mContactConstraints[c].r2Friction.y - v2.y * mContactConstraints[c].r2Friction.x - v1.z -
w1.x * mContactConstraints[c].r1Friction.y + w1.y * mContactConstraints[c].r1Friction.x;
Jv = deltaV.x * mContactConstraints[c].frictionVector2.x + deltaV.y * mContactConstraints[c].frictionVector2.y +
deltaV.z * mContactConstraints[c].frictionVector2.z;
// Compute the Lagrange multiplier lambda
deltaLambda = -Jv * mContactConstraints[c].inverseFriction2Mass;
frictionLimit = mContactConstraints[c].frictionCoefficient * sumPenetrationImpulse;
lambdaTemp = mContactConstraints[c].friction2Impulse;
mContactConstraints[c].friction2Impulse = std::max(-frictionLimit,
std::min(mContactConstraints[c].friction2Impulse +
deltaLambda, frictionLimit));
deltaLambda = mContactConstraints[c].friction2Impulse - lambdaTemp;
// Compute the impulse P=J^T * lambda
angularImpulseBody1.x = -mContactConstraints[c].r1CrossT2.x * deltaLambda;
angularImpulseBody1.y = -mContactConstraints[c].r1CrossT2.y * deltaLambda;
angularImpulseBody1.z = -mContactConstraints[c].r1CrossT2.z * deltaLambda;
linearImpulseBody2.x = mContactConstraints[c].frictionVector2.x * deltaLambda;
linearImpulseBody2.y = mContactConstraints[c].frictionVector2.y * deltaLambda;
linearImpulseBody2.z = mContactConstraints[c].frictionVector2.z * deltaLambda;
angularImpulseBody2.x = mContactConstraints[c].r2CrossT2.x * deltaLambda;
angularImpulseBody2.y = mContactConstraints[c].r2CrossT2.y * deltaLambda;
angularImpulseBody2.z = mContactConstraints[c].r2CrossT2.z * deltaLambda;
// Update the velocities of the body 1 by applying the impulse P
mLinearVelocities[mContactConstraints[c].indexBody1].x -= mContactConstraints[c].massInverseBody1 * linearImpulseBody2.x;
mLinearVelocities[mContactConstraints[c].indexBody1].y -= mContactConstraints[c].massInverseBody1 * linearImpulseBody2.y;
mLinearVelocities[mContactConstraints[c].indexBody1].z -= mContactConstraints[c].massInverseBody1 * linearImpulseBody2.z;
mAngularVelocities[mContactConstraints[c].indexBody1] += mContactConstraints[c].inverseInertiaTensorBody1 * angularImpulseBody1;
// Update the velocities of the body 2 by applying the impulse P
mLinearVelocities[mContactConstraints[c].indexBody2].x += mContactConstraints[c].massInverseBody2 * linearImpulseBody2.x;
mLinearVelocities[mContactConstraints[c].indexBody2].y += mContactConstraints[c].massInverseBody2 * linearImpulseBody2.y;
mLinearVelocities[mContactConstraints[c].indexBody2].z += mContactConstraints[c].massInverseBody2 * linearImpulseBody2.z;
mAngularVelocities[mContactConstraints[c].indexBody2] += mContactConstraints[c].inverseInertiaTensorBody2 * angularImpulseBody2;
// ------ Twist friction constraint at the center of the contact manifol ------ //
// Compute J*v
deltaV = w2 - w1;
Jv = deltaV.x * mContactConstraints[c].normal.x + deltaV.y * mContactConstraints[c].normal.y +
deltaV.z * mContactConstraints[c].normal.z;
deltaLambda = -Jv * (mContactConstraints[c].inverseTwistFrictionMass);
frictionLimit = mContactConstraints[c].frictionCoefficient * sumPenetrationImpulse;
lambdaTemp = mContactConstraints[c].frictionTwistImpulse;
mContactConstraints[c].frictionTwistImpulse = std::max(-frictionLimit,
std::min(mContactConstraints[c].frictionTwistImpulse
+ deltaLambda, frictionLimit));
deltaLambda = mContactConstraints[c].frictionTwistImpulse - lambdaTemp;
// Compute the impulse P=J^T * lambda
angularImpulseBody2.x = mContactConstraints[c].normal.x * deltaLambda;
angularImpulseBody2.y = mContactConstraints[c].normal.y * deltaLambda;
angularImpulseBody2.z = mContactConstraints[c].normal.z * deltaLambda;
// Update the velocities of the body 1 by applying the impulse P
mAngularVelocities[mContactConstraints[c].indexBody1] -= mContactConstraints[c].inverseInertiaTensorBody1 * angularImpulseBody2;
// Update the velocities of the body 1 by applying the impulse P
mAngularVelocities[mContactConstraints[c].indexBody2] += mContactConstraints[c].inverseInertiaTensorBody2 * angularImpulseBody2;
// --------- Rolling resistance constraint at the center of the contact manifold --------- //
if (mContactConstraints[c].rollingResistanceFactor > 0) {
// Compute J*v
const Vector3 JvRolling = w2 - w1;
// Compute the Lagrange multiplier lambda
Vector3 deltaLambdaRolling = mContactConstraints[c].inverseRollingResistance * (-JvRolling);
decimal rollingLimit = mContactConstraints[c].rollingResistanceFactor * sumPenetrationImpulse;
Vector3 lambdaTempRolling = mContactConstraints[c].rollingResistanceImpulse;
mContactConstraints[c].rollingResistanceImpulse = clamp(mContactConstraints[c].rollingResistanceImpulse +
deltaLambdaRolling, rollingLimit);
deltaLambdaRolling = mContactConstraints[c].rollingResistanceImpulse - lambdaTempRolling;
// Update the velocities of the body 1 by applying the impulse P
mAngularVelocities[mContactConstraints[c].indexBody1] -= mContactConstraints[c].inverseInertiaTensorBody1 * deltaLambdaRolling;
// Update the velocities of the body 2 by applying the impulse P
mAngularVelocities[mContactConstraints[c].indexBody2] += mContactConstraints[c].inverseInertiaTensorBody2 * deltaLambdaRolling;
}
}
}
// Store the computed impulses to use them to
// warm start the solver at the next iteration
void ContactSolver::storeImpulses() {
RP3D_PROFILE("ContactSolver::storeImpulses()", mProfiler);
uint contactPointIndex = 0;
// For each contact manifold
for (uint c=0; c<mNbContactManifolds; c++) {
for (short int i=0; i<mContactConstraints[c].nbContacts; i++) {
mContactPoints[contactPointIndex].externalContact->setPenetrationImpulse(mContactPoints[contactPointIndex].penetrationImpulse);
contactPointIndex++;
}
mContactConstraints[c].externalContactManifold->setFrictionImpulse1(mContactConstraints[c].friction1Impulse);
mContactConstraints[c].externalContactManifold->setFrictionImpulse2(mContactConstraints[c].friction2Impulse);
mContactConstraints[c].externalContactManifold->setFrictionTwistImpulse(mContactConstraints[c].frictionTwistImpulse);
mContactConstraints[c].externalContactManifold->setRollingResistanceImpulse(mContactConstraints[c].rollingResistanceImpulse);
mContactConstraints[c].externalContactManifold->setFrictionVector1(mContactConstraints[c].frictionVector1);
mContactConstraints[c].externalContactManifold->setFrictionVector2(mContactConstraints[c].frictionVector2);
}
}
// Compute the two unit orthogonal vectors "t1" and "t2" that span the tangential friction plane
// for a contact manifold. The two vectors have to be such that : t1 x t2 = contactNormal.
void ContactSolver::computeFrictionVectors(const Vector3& deltaVelocity,
ContactManifoldSolver& contact) const {
RP3D_PROFILE("ContactSolver::computeFrictionVectors()", mProfiler);
assert(contact.normal.length() > decimal(0.0));
// Compute the velocity difference vector in the tangential plane
Vector3 normalVelocity(deltaVelocity.x * contact.normal.x * contact.normal.x,
deltaVelocity.y * contact.normal.y * contact.normal.y,
deltaVelocity.z * contact.normal.z * contact.normal.z);
Vector3 tangentVelocity(deltaVelocity.x - normalVelocity.x, deltaVelocity.y - normalVelocity.y,
deltaVelocity.z - normalVelocity.z);
// If the velocty difference in the tangential plane is not zero
decimal lengthTangenVelocity = tangentVelocity.length();
if (lengthTangenVelocity > MACHINE_EPSILON) {
// Compute the first friction vector in the direction of the tangent
// velocity difference
contact.frictionVector1 = tangentVelocity / lengthTangenVelocity;
}
else {
// Get any orthogonal vector to the normal as the first friction vector
contact.frictionVector1 = contact.normal.getOneUnitOrthogonalVector();
}
// The second friction vector is computed by the cross product of the firs
// friction vector and the contact normal
contact.frictionVector2 = contact.normal.cross(contact.frictionVector1).getUnit();
}