537 lines
26 KiB
C++
537 lines
26 KiB
C++
/********************************************************************************
|
|
* ReactPhysics3D physics library, http://www.reactphysics3d.com *
|
|
* Copyright (c) 2010-2018 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 "systems/SolveFixedJointSystem.h"
|
|
#include "engine/PhysicsWorld.h"
|
|
#include "body/RigidBody.h"
|
|
|
|
using namespace reactphysics3d;
|
|
|
|
// Static variables definition
|
|
const decimal SolveFixedJointSystem::BETA = decimal(0.2);
|
|
|
|
// Constructor
|
|
SolveFixedJointSystem::SolveFixedJointSystem(PhysicsWorld& world, RigidBodyComponents& rigidBodyComponents,
|
|
TransformComponents& transformComponents,
|
|
JointComponents& jointComponents,
|
|
FixedJointComponents& fixedJointComponents)
|
|
:mWorld(world), mRigidBodyComponents(rigidBodyComponents), mTransformComponents(transformComponents),
|
|
mJointComponents(jointComponents), mFixedJointComponents(fixedJointComponents),
|
|
mTimeStep(0), mIsWarmStartingActive(true) {
|
|
|
|
}
|
|
|
|
// Initialize before solving the constraint
|
|
void SolveFixedJointSystem::initBeforeSolve() {
|
|
|
|
// For each joint
|
|
for (uint32 i=0; i < mFixedJointComponents.getNbEnabledComponents(); i++) {
|
|
|
|
const Entity jointEntity = mFixedJointComponents.mJointEntities[i];
|
|
|
|
// Get the bodies entities
|
|
const Entity body1Entity = mJointComponents.getBody1Entity(jointEntity);
|
|
const Entity body2Entity = mJointComponents.getBody2Entity(jointEntity);
|
|
|
|
assert(!mRigidBodyComponents.getIsEntityDisabled(body1Entity));
|
|
assert(!mRigidBodyComponents.getIsEntityDisabled(body2Entity));
|
|
|
|
// Get the inertia tensor of bodies
|
|
mFixedJointComponents.mI1[i] = RigidBody::getInertiaTensorInverseWorld(mWorld, body1Entity);
|
|
mFixedJointComponents.mI2[i] = RigidBody::getInertiaTensorInverseWorld(mWorld, body2Entity);
|
|
}
|
|
|
|
// For each joint
|
|
for (uint32 i=0; i < mFixedJointComponents.getNbEnabledComponents(); i++) {
|
|
|
|
const Entity jointEntity = mFixedJointComponents.mJointEntities[i];
|
|
|
|
// Get the bodies entities
|
|
const Entity body1Entity = mJointComponents.getBody1Entity(jointEntity);
|
|
const Entity body2Entity = mJointComponents.getBody2Entity(jointEntity);
|
|
|
|
const Quaternion& orientationBody1 = mTransformComponents.getTransform(body1Entity).getOrientation();
|
|
const Quaternion& orientationBody2 = mTransformComponents.getTransform(body2Entity).getOrientation();
|
|
|
|
// Compute the vector from body center to the anchor point in world-space
|
|
mFixedJointComponents.mR1World[i] = orientationBody1 * mFixedJointComponents.mLocalAnchorPointBody1[i];
|
|
mFixedJointComponents.mR2World[i] = orientationBody2 * mFixedJointComponents.mLocalAnchorPointBody2[i];
|
|
}
|
|
|
|
// For each joint
|
|
for (uint32 i=0; i < mFixedJointComponents.getNbEnabledComponents(); i++) {
|
|
|
|
const Entity jointEntity = mFixedJointComponents.mJointEntities[i];
|
|
|
|
// Get the bodies entities
|
|
const Entity body1Entity = mJointComponents.getBody1Entity(jointEntity);
|
|
const Entity body2Entity = mJointComponents.getBody2Entity(jointEntity);
|
|
|
|
// Compute the corresponding skew-symmetric matrices
|
|
Matrix3x3 skewSymmetricMatrixU1 = Matrix3x3::computeSkewSymmetricMatrixForCrossProduct(mFixedJointComponents.mR1World[i]);
|
|
Matrix3x3 skewSymmetricMatrixU2 = Matrix3x3::computeSkewSymmetricMatrixForCrossProduct(mFixedJointComponents.mR2World[i]);
|
|
|
|
const uint32 componentIndexBody1 = mRigidBodyComponents.getEntityIndex(body1Entity);
|
|
const uint32 componentIndexBody2 = mRigidBodyComponents.getEntityIndex(body2Entity);
|
|
|
|
// Compute the matrix K=JM^-1J^t (3x3 matrix) for the 3 translation constraints
|
|
const decimal body1MassInverse = mRigidBodyComponents.mInverseMasses[componentIndexBody1];
|
|
const decimal body2MassInverse = mRigidBodyComponents.mInverseMasses[componentIndexBody2];
|
|
const decimal inverseMassBodies = body1MassInverse + body2MassInverse;
|
|
Matrix3x3 massMatrix = Matrix3x3(inverseMassBodies, 0, 0,
|
|
0, inverseMassBodies, 0,
|
|
0, 0, inverseMassBodies) +
|
|
skewSymmetricMatrixU1 * mFixedJointComponents.mI1[i] * skewSymmetricMatrixU1.getTranspose() +
|
|
skewSymmetricMatrixU2 * mFixedJointComponents.mI2[i] * skewSymmetricMatrixU2.getTranspose();
|
|
|
|
// Compute the inverse mass matrix K^-1 for the 3 translation constraints
|
|
mFixedJointComponents.mInverseMassMatrixTranslation[i].setToZero();
|
|
if (mRigidBodyComponents.mBodyTypes[componentIndexBody1] == BodyType::DYNAMIC ||
|
|
mRigidBodyComponents.mBodyTypes[componentIndexBody2] == BodyType::DYNAMIC) {
|
|
mFixedJointComponents.mInverseMassMatrixTranslation[i] = massMatrix.getInverse();
|
|
}
|
|
}
|
|
|
|
const decimal biasFactor = BETA / mTimeStep;
|
|
|
|
// For each joint
|
|
for (uint32 i=0; i < mFixedJointComponents.getNbEnabledComponents(); i++) {
|
|
|
|
const Entity jointEntity = mFixedJointComponents.mJointEntities[i];
|
|
|
|
// Get the bodies entities
|
|
const Entity body1Entity = mJointComponents.getBody1Entity(jointEntity);
|
|
const Entity body2Entity = mJointComponents.getBody2Entity(jointEntity);
|
|
|
|
// Get the bodies positions and orientations
|
|
const Vector3& x1 = mRigidBodyComponents.getCenterOfMassWorld(body1Entity);
|
|
const Vector3& x2 = mRigidBodyComponents.getCenterOfMassWorld(body2Entity);
|
|
|
|
const Vector3& r1World = mFixedJointComponents.mR1World[i];
|
|
const Vector3& r2World = mFixedJointComponents.mR2World[i];
|
|
|
|
// Compute the bias "b" of the constraint for the 3 translation constraints
|
|
mFixedJointComponents.mBiasTranslation[i].setToZero();
|
|
if (mJointComponents.getPositionCorrectionTechnique(jointEntity) == JointsPositionCorrectionTechnique::BAUMGARTE_JOINTS) {
|
|
mFixedJointComponents.mBiasTranslation[i] = biasFactor * (x2 + r2World - x1 - r1World);
|
|
}
|
|
}
|
|
|
|
// For each joint
|
|
for (uint32 i=0; i < mFixedJointComponents.getNbEnabledComponents(); i++) {
|
|
|
|
const Entity jointEntity = mFixedJointComponents.mJointEntities[i];
|
|
|
|
// Get the bodies entities
|
|
const Entity body1Entity = mJointComponents.getBody1Entity(jointEntity);
|
|
const Entity body2Entity = mJointComponents.getBody2Entity(jointEntity);
|
|
|
|
// Compute the inverse of the mass matrix K=JM^-1J^t for the 3 rotation contraints (3x3 matrix)
|
|
mFixedJointComponents.mInverseMassMatrixRotation[i] = mFixedJointComponents.mI1[i] + mFixedJointComponents.mI2[i];
|
|
if (mRigidBodyComponents.getBodyType(body1Entity) == BodyType::DYNAMIC ||
|
|
mRigidBodyComponents.getBodyType(body2Entity) == BodyType::DYNAMIC) {
|
|
mFixedJointComponents.mInverseMassMatrixRotation[i] = mFixedJointComponents.mInverseMassMatrixRotation[i].getInverse();
|
|
}
|
|
}
|
|
|
|
// For each joint
|
|
for (uint32 i=0; i < mFixedJointComponents.getNbEnabledComponents(); i++) {
|
|
|
|
const Entity jointEntity = mFixedJointComponents.mJointEntities[i];
|
|
|
|
// Get the bodies entities
|
|
const Entity body1Entity = mJointComponents.getBody1Entity(jointEntity);
|
|
const Entity body2Entity = mJointComponents.getBody2Entity(jointEntity);
|
|
|
|
// Compute the bias "b" for the 3 rotation constraints
|
|
mFixedJointComponents.mBiasRotation[i].setToZero();
|
|
|
|
const Quaternion& orientationBody1 = mTransformComponents.getTransform(body1Entity).getOrientation();
|
|
const Quaternion& orientationBody2 = mTransformComponents.getTransform(body2Entity).getOrientation();
|
|
|
|
if (mJointComponents.getPositionCorrectionTechnique(jointEntity) == JointsPositionCorrectionTechnique::BAUMGARTE_JOINTS) {
|
|
const Quaternion qError = orientationBody2 * mFixedJointComponents.mInitOrientationDifferenceInv[i] * orientationBody1.getInverse();
|
|
mFixedJointComponents.mBiasRotation[i] = biasFactor * decimal(2.0) * qError.getVectorV();
|
|
}
|
|
}
|
|
|
|
// If warm-starting is not enabled
|
|
if (!mIsWarmStartingActive) {
|
|
|
|
// For each joint
|
|
for (uint32 i=0; i < mFixedJointComponents.getNbEnabledComponents(); i++) {
|
|
|
|
// Reset the accumulated impulses
|
|
mFixedJointComponents.mImpulseTranslation[i].setToZero();
|
|
mFixedJointComponents.mImpulseRotation[i].setToZero();
|
|
}
|
|
}
|
|
}
|
|
|
|
// Warm start the constraint (apply the previous impulse at the beginning of the step)
|
|
void SolveFixedJointSystem::warmstart() {
|
|
|
|
// For each joint
|
|
for (uint32 i=0; i < mFixedJointComponents.getNbEnabledComponents(); i++) {
|
|
|
|
const Entity jointEntity = mFixedJointComponents.mJointEntities[i];
|
|
|
|
// Get the bodies entities
|
|
const Entity body1Entity = mJointComponents.getBody1Entity(jointEntity);
|
|
const Entity body2Entity = mJointComponents.getBody2Entity(jointEntity);
|
|
|
|
const uint32 componentIndexBody1 = mRigidBodyComponents.getEntityIndex(body1Entity);
|
|
const uint32 componentIndexBody2 = mRigidBodyComponents.getEntityIndex(body2Entity);
|
|
|
|
// Get the velocities
|
|
Vector3& v1 = mRigidBodyComponents.mConstrainedLinearVelocities[componentIndexBody1];
|
|
Vector3& v2 = mRigidBodyComponents.mConstrainedLinearVelocities[componentIndexBody2];
|
|
Vector3& w1 = mRigidBodyComponents.mConstrainedAngularVelocities[componentIndexBody1];
|
|
Vector3& w2 = mRigidBodyComponents.mConstrainedAngularVelocities[componentIndexBody2];
|
|
|
|
// Get the inverse mass of the bodies
|
|
const decimal inverseMassBody1 = mRigidBodyComponents.mInverseMasses[componentIndexBody1];
|
|
const decimal inverseMassBody2 = mRigidBodyComponents.mInverseMasses[componentIndexBody2];
|
|
|
|
const Vector3& impulseTranslation = mFixedJointComponents.mImpulseTranslation[i];
|
|
const Vector3& impulseRotation = mFixedJointComponents.mImpulseRotation[i];
|
|
|
|
const Vector3& r1World = mFixedJointComponents.mR1World[i];
|
|
const Vector3& r2World = mFixedJointComponents.mR2World[i];
|
|
|
|
// Compute the impulse P=J^T * lambda for the 3 translation constraints for body 1
|
|
Vector3 linearImpulseBody1 = -impulseTranslation;
|
|
Vector3 angularImpulseBody1 = impulseTranslation.cross(r1World);
|
|
|
|
// Compute the impulse P=J^T * lambda for the 3 rotation constraints for body 1
|
|
angularImpulseBody1 += -impulseRotation;
|
|
|
|
const Matrix3x3& i1 = mFixedJointComponents.mI1[i];
|
|
|
|
// Apply the impulse to the body 1
|
|
v1 += inverseMassBody1 * linearImpulseBody1;
|
|
w1 += i1 * angularImpulseBody1;
|
|
|
|
// Compute the impulse P=J^T * lambda for the 3 translation constraints for body 2
|
|
Vector3 angularImpulseBody2 = -impulseTranslation.cross(r2World);
|
|
|
|
// Compute the impulse P=J^T * lambda for the 3 rotation constraints for body 2
|
|
angularImpulseBody2 += impulseRotation;
|
|
|
|
const Matrix3x3& i2 = mFixedJointComponents.mI2[i];
|
|
|
|
// Apply the impulse to the body 2
|
|
v2 += inverseMassBody2 * impulseTranslation;
|
|
w2 += i2 * angularImpulseBody2;
|
|
}
|
|
}
|
|
|
|
// Solve the velocity constraint
|
|
void SolveFixedJointSystem::solveVelocityConstraint() {
|
|
|
|
// For each joint
|
|
for (uint32 i=0; i < mFixedJointComponents.getNbEnabledComponents(); i++) {
|
|
|
|
const Entity jointEntity = mFixedJointComponents.mJointEntities[i];
|
|
|
|
// Get the bodies entities
|
|
const Entity body1Entity = mJointComponents.getBody1Entity(jointEntity);
|
|
const Entity body2Entity = mJointComponents.getBody2Entity(jointEntity);
|
|
|
|
const uint32 componentIndexBody1 = mRigidBodyComponents.getEntityIndex(body1Entity);
|
|
const uint32 componentIndexBody2 = mRigidBodyComponents.getEntityIndex(body2Entity);
|
|
|
|
// Get the velocities
|
|
Vector3& v1 = mRigidBodyComponents.mConstrainedLinearVelocities[componentIndexBody1];
|
|
Vector3& v2 = mRigidBodyComponents.mConstrainedLinearVelocities[componentIndexBody2];
|
|
Vector3& w1 = mRigidBodyComponents.mConstrainedAngularVelocities[componentIndexBody1];
|
|
Vector3& w2 = mRigidBodyComponents.mConstrainedAngularVelocities[componentIndexBody2];
|
|
|
|
// Get the inverse mass of the bodies
|
|
decimal inverseMassBody1 = mRigidBodyComponents.mInverseMasses[componentIndexBody1];
|
|
decimal inverseMassBody2 = mRigidBodyComponents.mInverseMasses[componentIndexBody2];
|
|
|
|
const Vector3& r1World = mFixedJointComponents.mR1World[i];
|
|
const Vector3& r2World = mFixedJointComponents.mR2World[i];
|
|
|
|
// --------------- Translation Constraints --------------- //
|
|
|
|
// Compute J*v for the 3 translation constraints
|
|
const Vector3 JvTranslation = v2 + w2.cross(r2World) - v1 - w1.cross(r1World);
|
|
|
|
const Matrix3x3& inverseMassMatrixTranslation = mFixedJointComponents.mInverseMassMatrixTranslation[i];
|
|
|
|
// Compute the Lagrange multiplier lambda
|
|
const Vector3 deltaLambda = inverseMassMatrixTranslation * (-JvTranslation - mFixedJointComponents.mBiasTranslation[i]);
|
|
mFixedJointComponents.mImpulseTranslation[i] += deltaLambda;
|
|
|
|
// Compute the impulse P=J^T * lambda for body 1
|
|
const Vector3 linearImpulseBody1 = -deltaLambda;
|
|
Vector3 angularImpulseBody1 = deltaLambda.cross(r1World);
|
|
|
|
const Matrix3x3& i1 = mFixedJointComponents.mI1[i];
|
|
|
|
// Apply the impulse to the body 1
|
|
v1 += inverseMassBody1 * linearImpulseBody1;
|
|
w1 += i1 * angularImpulseBody1;
|
|
|
|
// Compute the impulse P=J^T * lambda for body 2
|
|
const Vector3 angularImpulseBody2 = -deltaLambda.cross(r2World);
|
|
|
|
const Matrix3x3& i2 = mFixedJointComponents.mI2[i];
|
|
|
|
// Apply the impulse to the body 2
|
|
v2 += inverseMassBody2 * deltaLambda;
|
|
w2 += i2 * angularImpulseBody2;
|
|
|
|
// --------------- Rotation Constraints --------------- //
|
|
|
|
// Compute J*v for the 3 rotation constraints
|
|
const Vector3 JvRotation = w2 - w1;
|
|
|
|
const Vector3& biasRotation = mFixedJointComponents.mBiasRotation[i];
|
|
const Matrix3x3& inverseMassMatrixRotation = mFixedJointComponents.mInverseMassMatrixRotation[i];
|
|
|
|
// Compute the Lagrange multiplier lambda for the 3 rotation constraints
|
|
Vector3 deltaLambda2 = inverseMassMatrixRotation * (-JvRotation - biasRotation);
|
|
mFixedJointComponents.mImpulseRotation[i] += deltaLambda2;
|
|
|
|
// Compute the impulse P=J^T * lambda for the 3 rotation constraints for body 1
|
|
angularImpulseBody1 = -deltaLambda2;
|
|
|
|
// Apply the impulse to the body 1
|
|
w1 += i1 * angularImpulseBody1;
|
|
|
|
// Apply the impulse to the body 2
|
|
w2 += i2 * deltaLambda2;
|
|
}
|
|
}
|
|
|
|
// Solve the position constraint (for position error correction)
|
|
void SolveFixedJointSystem::solvePositionConstraint() {
|
|
|
|
// For each joint
|
|
for (uint32 i=0; i < mFixedJointComponents.getNbEnabledComponents(); i++) {
|
|
|
|
const Entity jointEntity = mFixedJointComponents.mJointEntities[i];
|
|
|
|
// If the error position correction technique is not the non-linear-gauss-seidel, we do
|
|
// do not execute this method
|
|
if (mJointComponents.getPositionCorrectionTechnique(jointEntity) != JointsPositionCorrectionTechnique::NON_LINEAR_GAUSS_SEIDEL) continue;
|
|
|
|
// Get the bodies entities
|
|
const Entity body1Entity = mJointComponents.getBody1Entity(jointEntity);
|
|
const Entity body2Entity = mJointComponents.getBody2Entity(jointEntity);
|
|
|
|
// Recompute the inverse inertia tensors
|
|
mFixedJointComponents.mI1[i] = RigidBody::getInertiaTensorInverseWorld(mWorld, body1Entity);
|
|
mFixedJointComponents.mI2[i] = RigidBody::getInertiaTensorInverseWorld(mWorld, body2Entity);
|
|
}
|
|
|
|
// For each joint
|
|
for (uint32 i=0; i < mFixedJointComponents.getNbEnabledComponents(); i++) {
|
|
|
|
const Entity jointEntity = mFixedJointComponents.mJointEntities[i];
|
|
|
|
// If the error position correction technique is not the non-linear-gauss-seidel, we do
|
|
// do not execute this method
|
|
if (mJointComponents.getPositionCorrectionTechnique(jointEntity) != JointsPositionCorrectionTechnique::NON_LINEAR_GAUSS_SEIDEL) continue;
|
|
|
|
// Get the bodies entities
|
|
const Entity body1Entity = mJointComponents.getBody1Entity(jointEntity);
|
|
const Entity body2Entity = mJointComponents.getBody2Entity(jointEntity);
|
|
|
|
// Get the bodies positions and orientations
|
|
const Quaternion& q1 = mRigidBodyComponents.getConstrainedOrientation(body1Entity);
|
|
const Quaternion& q2 = mRigidBodyComponents.getConstrainedOrientation(body2Entity);
|
|
|
|
// Compute the vector from body center to the anchor point in world-space
|
|
mFixedJointComponents.mR1World[i] = q1 * mFixedJointComponents.getLocalAnchorPointBody1(jointEntity);
|
|
mFixedJointComponents.mR2World[i] = q2 * mFixedJointComponents.getLocalAnchorPointBody2(jointEntity);
|
|
}
|
|
|
|
// For each joint
|
|
for (uint32 i=0; i < mFixedJointComponents.getNbEnabledComponents(); i++) {
|
|
|
|
const Entity jointEntity = mFixedJointComponents.mJointEntities[i];
|
|
|
|
// If the error position correction technique is not the non-linear-gauss-seidel, we do
|
|
// do not execute this method
|
|
if (mJointComponents.getPositionCorrectionTechnique(jointEntity) != JointsPositionCorrectionTechnique::NON_LINEAR_GAUSS_SEIDEL) continue;
|
|
|
|
// Get the bodies entities
|
|
const Entity body1Entity = mJointComponents.getBody1Entity(jointEntity);
|
|
const Entity body2Entity = mJointComponents.getBody2Entity(jointEntity);
|
|
|
|
const uint32 componentIndexBody1 = mRigidBodyComponents.getEntityIndex(body1Entity);
|
|
const uint32 componentIndexBody2 = mRigidBodyComponents.getEntityIndex(body2Entity);
|
|
|
|
// Get the inverse mass and inverse inertia tensors of the bodies
|
|
decimal inverseMassBody1 = mRigidBodyComponents.mInverseMasses[componentIndexBody1];
|
|
decimal inverseMassBody2 = mRigidBodyComponents.mInverseMasses[componentIndexBody2];
|
|
|
|
const Vector3& r1World = mFixedJointComponents.mR1World[i];
|
|
const Vector3& r2World = mFixedJointComponents.mR2World[i];
|
|
|
|
// Compute the corresponding skew-symmetric matrices
|
|
Matrix3x3 skewSymmetricMatrixU1= Matrix3x3::computeSkewSymmetricMatrixForCrossProduct(r1World);
|
|
Matrix3x3 skewSymmetricMatrixU2= Matrix3x3::computeSkewSymmetricMatrixForCrossProduct(r2World);
|
|
|
|
// --------------- Translation Constraints --------------- //
|
|
|
|
// Compute the matrix K=JM^-1J^t (3x3 matrix) for the 3 translation constraints
|
|
decimal inverseMassBodies = inverseMassBody1 + inverseMassBody2;
|
|
Matrix3x3 massMatrix = Matrix3x3(inverseMassBodies, 0, 0,
|
|
0, inverseMassBodies, 0,
|
|
0, 0, inverseMassBodies) +
|
|
skewSymmetricMatrixU1 * mFixedJointComponents.mI1[i] * skewSymmetricMatrixU1.getTranspose() +
|
|
skewSymmetricMatrixU2 * mFixedJointComponents.mI2[i] * skewSymmetricMatrixU2.getTranspose();
|
|
mFixedJointComponents.mInverseMassMatrixTranslation[i].setToZero();
|
|
if (mRigidBodyComponents.mBodyTypes[componentIndexBody1] == BodyType::DYNAMIC ||
|
|
mRigidBodyComponents.mBodyTypes[componentIndexBody2] == BodyType::DYNAMIC) {
|
|
mFixedJointComponents.mInverseMassMatrixTranslation[i] = massMatrix.getInverse();
|
|
}
|
|
}
|
|
|
|
// For each joint
|
|
for (uint32 i=0; i < mFixedJointComponents.getNbEnabledComponents(); i++) {
|
|
|
|
const Entity jointEntity = mFixedJointComponents.mJointEntities[i];
|
|
|
|
// If the error position correction technique is not the non-linear-gauss-seidel, we do
|
|
// do not execute this method
|
|
if (mJointComponents.getPositionCorrectionTechnique(jointEntity) != JointsPositionCorrectionTechnique::NON_LINEAR_GAUSS_SEIDEL) continue;
|
|
|
|
// Get the bodies entities
|
|
const Entity body1Entity = mJointComponents.getBody1Entity(jointEntity);
|
|
const Entity body2Entity = mJointComponents.getBody2Entity(jointEntity);
|
|
|
|
const Vector3& r1World = mFixedJointComponents.mR1World[i];
|
|
const Vector3& r2World = mFixedJointComponents.mR2World[i];
|
|
|
|
const uint32 componentIndexBody1 = mRigidBodyComponents.getEntityIndex(body1Entity);
|
|
const uint32 componentIndexBody2 = mRigidBodyComponents.getEntityIndex(body2Entity);
|
|
|
|
Vector3& x1 = mRigidBodyComponents.mConstrainedPositions[componentIndexBody1];
|
|
Vector3& x2 = mRigidBodyComponents.mConstrainedPositions[componentIndexBody2];
|
|
Quaternion& q1 = mRigidBodyComponents.mConstrainedOrientations[componentIndexBody1];
|
|
Quaternion& q2 = mRigidBodyComponents.mConstrainedOrientations[componentIndexBody2];
|
|
|
|
// Compute position error for the 3 translation constraints
|
|
const Vector3 errorTranslation = x2 + r2World - x1 - r1World;
|
|
|
|
// Compute the Lagrange multiplier lambda
|
|
const Vector3 lambdaTranslation = mFixedJointComponents.mInverseMassMatrixTranslation[i] * (-errorTranslation);
|
|
|
|
// Compute the impulse of body 1
|
|
Vector3 linearImpulseBody1 = -lambdaTranslation;
|
|
Vector3 angularImpulseBody1 = lambdaTranslation.cross(r1World);
|
|
|
|
const decimal inverseMassBody1 = mRigidBodyComponents.mInverseMasses[componentIndexBody1];
|
|
|
|
// Compute the pseudo velocity of body 1
|
|
const Vector3 v1 = inverseMassBody1 * linearImpulseBody1;
|
|
Vector3 w1 = mFixedJointComponents.mI2[i] * angularImpulseBody1;
|
|
|
|
// Update the body position/orientation of body 1
|
|
x1 += v1;
|
|
q1 += Quaternion(0, w1) * q1 * decimal(0.5);
|
|
q1.normalize();
|
|
|
|
// Compute the impulse of body 2
|
|
Vector3 angularImpulseBody2 = -lambdaTranslation.cross(r2World);
|
|
|
|
const decimal inverseMassBody2 = mRigidBodyComponents.mInverseMasses[componentIndexBody2];
|
|
|
|
// Compute the pseudo velocity of body 2
|
|
const Vector3 v2 = inverseMassBody2 * lambdaTranslation;
|
|
Vector3 w2 = mFixedJointComponents.mI2[i] * angularImpulseBody2;
|
|
|
|
// Update the body position/orientation of body 2
|
|
x2 += v2;
|
|
q2 += Quaternion(0, w2) * q2 * decimal(0.5);
|
|
q2.normalize();
|
|
|
|
// --------------- Rotation Constraints --------------- //
|
|
|
|
// Compute the inverse of the mass matrix K=JM^-1J^t for the 3 rotation
|
|
// contraints (3x3 matrix)
|
|
mFixedJointComponents.mInverseMassMatrixRotation[i] = mFixedJointComponents.mI1[i] + mFixedJointComponents.mI2[i];
|
|
if (mRigidBodyComponents.mBodyTypes[componentIndexBody1] == BodyType::DYNAMIC ||
|
|
mRigidBodyComponents.mBodyTypes[componentIndexBody2] == BodyType::DYNAMIC) {
|
|
mFixedJointComponents.mInverseMassMatrixRotation[i] = mFixedJointComponents.mInverseMassMatrixRotation[i].getInverse();
|
|
}
|
|
|
|
// Calculate difference in rotation
|
|
//
|
|
// The rotation should be:
|
|
//
|
|
// q2 = q1 r0
|
|
//
|
|
// But because of drift the actual rotation is:
|
|
//
|
|
// q2 = qError q1 r0
|
|
// <=> qError = q2 r0^-1 q1^-1
|
|
//
|
|
// Where:
|
|
// q1 = current rotation of body 1
|
|
// q2 = current rotation of body 2
|
|
// qError = error that needs to be reduced to zero
|
|
Quaternion qError = q2 * mFixedJointComponents.mInitOrientationDifferenceInv[i] * q1.getInverse();
|
|
|
|
// A quaternion can be seen as:
|
|
//
|
|
// q = [sin(theta / 2) * v, cos(theta/2)]
|
|
//
|
|
// Where:
|
|
// v = rotation vector
|
|
// theta = rotation angle
|
|
//
|
|
// If we assume theta is small (error is small) then sin(x) = x so an approximation of the error angles is:
|
|
const Vector3 errorRotation = decimal(2.0) * qError.getVectorV();
|
|
|
|
// Compute the Lagrange multiplier lambda for the 3 rotation constraints
|
|
Vector3 lambdaRotation = mFixedJointComponents.mInverseMassMatrixRotation[i] * (-errorRotation);
|
|
|
|
// Compute the impulse P=J^T * lambda for the 3 rotation constraints of body 1
|
|
angularImpulseBody1 = -lambdaRotation;
|
|
|
|
// Compute the pseudo velocity of body 1
|
|
w1 = mFixedJointComponents.mI1[i] * angularImpulseBody1;
|
|
|
|
// Update the body position/orientation of body 1
|
|
q1 += Quaternion(0, w1) * q1 * decimal(0.5);
|
|
q1.normalize();
|
|
|
|
// Compute the pseudo velocity of body 2
|
|
w2 = mFixedJointComponents.mI2[i] * lambdaRotation;
|
|
|
|
// Update the body position/orientation of body 2
|
|
q2 += Quaternion(0, w2) * q2 * decimal(0.5);
|
|
q2.normalize();
|
|
}
|
|
}
|