Remove rolling restistance constraint from contact solver. Angular damping has to be used instead

CHANGELOG.md

@@ -14,8 +14,13 @@ do not hesitate to take a look at the user manual.
 
 ### Changed
 
+ - Rolling resistance constraint is not solved anymore in the solver. Angular damping needs to be used instead to simulate this.
+
 ### Removed
 
+ - Method Material::getRollingResistance() has been removed (angular damping has to be used instead of rolling resistance)
+ - Method Material::setRollingResistance() has been removed (angular damping has to be used instead of rolling resistance)
+
 ### Fixed
 
 - Issue with concave vs convex shape collision detection has been fixed

include/reactphysics3d/collision/ContactManifold.h

@@ -95,9 +95,6 @@ class ContactManifold {
         /// Twist friction constraint accumulated impulse
         decimal frictionTwistImpulse;
 
-        /// Accumulated rolling resistance impulse
-        Vector3 rollingResistanceImpulse;
-
         /// True if the contact manifold has already been added into an island
         bool isAlreadyInIsland;
 

include/reactphysics3d/engine/Material.h

@@ -48,9 +48,6 @@ class Material {
         /// Square root of the friction coefficient
         decimal mFrictionCoefficientSqrt;
 
-        /// Rolling resistance factor (positive value)
-        decimal mRollingResistance;
-
         /// Bounciness during collisions (between 0 and 1) where 1 is for a very bouncy body
         decimal mBounciness;
 
@@ -60,7 +57,7 @@ class Material {
         // -------------------- Methods -------------------- //
 
         /// Constructor
-        Material(decimal frictionCoefficient, decimal rollingResistance, decimal bounciness, decimal massDensity = decimal(1.0));
+        Material(decimal frictionCoefficient, decimal bounciness, decimal massDensity = decimal(1.0));
 
     public :
 
@@ -81,12 +78,6 @@ class Material {
         /// Return the square root friction coefficient
         decimal getFrictionCoefficientSqrt() const;
 
-        /// Return the rolling resistance factor
-        decimal getRollingResistance() const;
-
-        /// Set the rolling resistance factor
-        void setRollingResistance(decimal rollingResistance);
-
         /// Return the mass density of the collider
         decimal getMassDensity() const;
 
@@ -146,27 +137,6 @@ RP3D_FORCE_INLINE decimal Material::getFrictionCoefficientSqrt() const {
     return mFrictionCoefficientSqrt;
 }
 
-// Return the rolling resistance factor. If this value is larger than zero,
-// it will be used to slow down the body when it is rolling
-// against another body.
-/**
- * @return The rolling resistance factor (positive value)
- */
-RP3D_FORCE_INLINE decimal Material::getRollingResistance() const {
-    return mRollingResistance;
-}
-
-// Set the rolling resistance factor. If this value is larger than zero,
-// it will be used to slow down the body when it is rolling
-// against another body.
-/**
- * @param rollingResistance The rolling resistance factor
- */
-RP3D_FORCE_INLINE void Material::setRollingResistance(decimal rollingResistance) {
-    assert(rollingResistance >= 0);
-    mRollingResistance = rollingResistance;
-}
-
 // Return the mass density of the collider
 RP3D_FORCE_INLINE decimal Material::getMassDensity() const {
    return mMassDensity;
@@ -186,7 +156,6 @@ RP3D_FORCE_INLINE std::string Material::to_string() const {
     std::stringstream ss;
 
     ss << "frictionCoefficient=" << (mFrictionCoefficientSqrt * mFrictionCoefficientSqrt) << std::endl;
-    ss << "rollingResistance=" << mRollingResistance << std::endl;
     ss << "bounciness=" << mBounciness << std::endl;
 
     return ss.str();

include/reactphysics3d/engine/PhysicsWorld.h

@@ -93,9 +93,6 @@ class PhysicsWorld {
             /// Velocity threshold for contact velocity restitution
             decimal restitutionVelocityThreshold;
 
-            /// Default rolling resistance
-            decimal defaultRollingRestistance;
-
             /// True if the sleeping technique is enabled
             bool isSleepingEnabled;
 
@@ -129,7 +126,6 @@ class PhysicsWorld {
                 defaultFrictionCoefficient = decimal(0.3);
                 defaultBounciness = decimal(0.5);
                 restitutionVelocityThreshold = decimal(0.5);
-                defaultRollingRestistance = decimal(0.0);
                 isSleepingEnabled = true;
                 defaultVelocitySolverNbIterations = 10;
                 defaultPositionSolverNbIterations = 5;
@@ -152,7 +148,6 @@ class PhysicsWorld {
                 ss << "defaultFrictionCoefficient=" << defaultFrictionCoefficient << std::endl;
                 ss << "defaultBounciness=" << defaultBounciness << std::endl;
                 ss << "restitutionVelocityThreshold=" << restitutionVelocityThreshold << std::endl;
-                ss << "defaultRollingRestistance=" << defaultRollingRestistance << std::endl;
                 ss << "isSleepingEnabled=" << isSleepingEnabled << std::endl;
                 ss << "defaultVelocitySolverNbIterations=" << defaultVelocitySolverNbIterations << std::endl;
                 ss << "defaultPositionSolverNbIterations=" << defaultPositionSolverNbIterations << std::endl;

include/reactphysics3d/mathematics/Matrix3x3.h

@@ -95,9 +95,6 @@ class Matrix3x3 {
         /// Return the inverse matrix
         Matrix3x3 getInverse() const;
 
-        /// Return the inverse matrix
-        Matrix3x3 getInverseWithDeterminant(decimal determinant) const;
-
         /// Return the matrix with absolute values
         Matrix3x3 getAbsoluteMatrix() const;
 

include/reactphysics3d/systems/ContactSolverSystem.h

@@ -199,9 +199,6 @@ class ContactSolverSystem {
             /// Mix friction coefficient for the two bodies
             decimal frictionCoefficient;
 
-            /// Rolling resistance factor between the two bodies
-            decimal rollingResistanceFactor;
-
             // - Variables used when friction constraints are apply at the center of the manifold-//
 
             /// Average normal vector of the contact manifold
@@ -240,9 +237,6 @@ class ContactSolverSystem {
             /// Matrix K for the twist friction constraint
             decimal inverseTwistFrictionMass;
 
-            /// Matrix K for the rolling resistance constraint
-            Matrix3x3 inverseRollingResistance;
-
             /// First friction direction at contact manifold center
             Vector3 frictionVector1;
 
@@ -264,9 +258,6 @@ class ContactSolverSystem {
             /// Twist friction impulse at contact manifold center
             decimal frictionTwistImpulse;
 
-            /// Rolling resistance impulse
-            Vector3 rollingResistanceImpulse;
-
             /// Number of contact points
             int8 nbContacts;
         };
@@ -344,9 +335,6 @@ class ContactSolverSystem {
         /// Compute the mixed friction coefficient from the friction coefficient of each collider
         decimal computeMixedFrictionCoefficient(const Material &material1, const Material &material2) const;
 
-        /// Compute th mixed rolling resistance factor between two colliders
-        decimal computeMixedRollingResistance(const Material& material1, const Material& material2) const;
-
         /// 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.
@@ -424,11 +412,6 @@ RP3D_FORCE_INLINE decimal ContactSolverSystem::computeMixedFrictionCoefficient(c
     return material1.getFrictionCoefficientSqrt() * material2.getFrictionCoefficientSqrt();
 }
 
-// Compute th mixed rolling resistance factor between two colliders
-RP3D_FORCE_INLINE decimal ContactSolverSystem::computeMixedRollingResistance(const Material& material1, const Material& material2) const {
-    return decimal(0.5f) * (material1.getRollingResistance() + material2.getRollingResistance());
-}
-
 #ifdef IS_RP3D_PROFILING_ENABLED
 
 // Set the profiler

src/body/CollisionBody.cpp

@@ -89,7 +89,7 @@ Collider* CollisionBody::addCollider(CollisionShape* collisionShape, const Trans
     // TODO : Maybe this method can directly returns an AABB
     collisionShape->getLocalBounds(localBoundsMin, localBoundsMax);
     const Transform localToWorldTransform = mWorld.mTransformComponents.getTransform(mEntity) * transform;
-    Material material(mWorld.mConfig.defaultFrictionCoefficient, mWorld.mConfig.defaultRollingRestistance, mWorld.mConfig.defaultBounciness);
+    Material material(mWorld.mConfig.defaultFrictionCoefficient, mWorld.mConfig.defaultBounciness);
     ColliderComponents::ColliderComponent colliderComponent(mEntity, collider, AABB(localBoundsMin, localBoundsMax),
                                                                   transform, collisionShape, 0x0001, 0xFFFF, localToWorldTransform, material);
     bool isActive = mWorld.mCollisionBodyComponents.getIsActive(mEntity);

src/body/RigidBody.cpp

@@ -590,7 +590,7 @@ Collider* RigidBody::addCollider(CollisionShape* collisionShape, const Transform
     // TODO : Maybe this method can directly returns an AABB
     collisionShape->getLocalBounds(localBoundsMin, localBoundsMax);
     const Transform localToWorldTransform = mWorld.mTransformComponents.getTransform(mEntity) * transform;
-    Material material(mWorld.mConfig.defaultFrictionCoefficient, mWorld.mConfig.defaultRollingRestistance, mWorld.mConfig.defaultBounciness);
+    Material material(mWorld.mConfig.defaultFrictionCoefficient, mWorld.mConfig.defaultBounciness);
     ColliderComponents::ColliderComponent colliderComponent(mEntity, collider, AABB(localBoundsMin, localBoundsMax),
                                                             transform, collisionShape, 0x0001, 0xFFFF, localToWorldTransform, material);
     bool isSleeping = mWorld.mRigidBodyComponents.getIsSleeping(mEntity);

src/engine/Material.cpp

@@ -29,8 +29,7 @@
 using namespace reactphysics3d;
 
 // Constructor
-Material::Material(decimal frictionCoefficient, decimal rollingResistance, decimal bounciness, decimal massDensity)
+Material::Material(decimal frictionCoefficient, decimal bounciness, decimal massDensity)
-         : mFrictionCoefficientSqrt(std::sqrt(frictionCoefficient)),
+         : mFrictionCoefficientSqrt(std::sqrt(frictionCoefficient)), mBounciness(bounciness), mMassDensity(massDensity) {
-           mRollingResistance(rollingResistance), mBounciness(bounciness), mMassDensity(massDensity) {
 
 }

src/mathematics/Matrix3x3.cpp

@@ -65,27 +65,3 @@ Matrix3x3 Matrix3x3::getInverse() const {
     // Return the inverse matrix
     return (invDeterminant * tempMatrix);
 }
-
-// Return the inverse matrix
-Matrix3x3 Matrix3x3::getInverseWithDeterminant(decimal determinant) const {
-
-    // Check if the determinant is equal to zero
-    assert(determinant != decimal(0.0));
-
-    decimal invDeterminant = decimal(1.0) / determinant;
-
-    Matrix3x3 tempMatrix((mRows[1][1]*mRows[2][2]-mRows[2][1]*mRows[1][2]),
-                         -(mRows[0][1]*mRows[2][2]-mRows[2][1]*mRows[0][2]),
-                         (mRows[0][1]*mRows[1][2]-mRows[0][2]*mRows[1][1]),
-                            -(mRows[1][0]*mRows[2][2]-mRows[2][0]*mRows[1][2]),
-                         (mRows[0][0]*mRows[2][2]-mRows[2][0]*mRows[0][2]),
-                         -(mRows[0][0]*mRows[1][2]-mRows[1][0]*mRows[0][2]),
-                            (mRows[1][0]*mRows[2][1]-mRows[2][0]*mRows[1][1]),
-                         -(mRows[0][0]*mRows[2][1]-mRows[2][0]*mRows[0][1]),
-                         (mRows[0][0]*mRows[1][1]-mRows[0][1]*mRows[1][0]));
-
-    // Return the inverse matrix
-    return (invDeterminant * tempMatrix);
-}
-
-

src/systems/CollisionDetectionSystem.cpp

@@ -903,7 +903,6 @@ void CollisionDetectionSystem::initContactsWithPreviousOnes() {
                         currentContactManifold.frictionImpulse1 = previousContactManifold.frictionImpulse1;
                         currentContactManifold.frictionImpulse2 = previousContactManifold.frictionImpulse2;
                         currentContactManifold.frictionTwistImpulse = previousContactManifold.frictionTwistImpulse;
-                        currentContactManifold.rollingResistanceImpulse = previousContactManifold.rollingResistanceImpulse;
 
                         break;
                     }

src/systems/ContactSolverSystem.cpp

@@ -153,7 +153,6 @@ void ContactSolverSystem::initializeForIsland(uint islandIndex) {
         mContactConstraints[mNbContactManifolds].massInverseBody2 = mRigidBodyComponents.mInverseMasses[rigidBodyIndex2];
         mContactConstraints[mNbContactManifolds].nbContacts = externalManifold.nbContactPoints;
         mContactConstraints[mNbContactManifolds].frictionCoefficient = computeMixedFrictionCoefficient(mColliderComponents.mMaterials[collider1Index], mColliderComponents.mMaterials[collider2Index]);
-        mContactConstraints[mNbContactManifolds].rollingResistanceFactor = computeMixedRollingResistance(mColliderComponents.mMaterials[collider1Index], mColliderComponents.mMaterials[collider2Index]);
         mContactConstraints[mNbContactManifolds].externalContactManifold = &externalManifold;
         mContactConstraints[mNbContactManifolds].normal.setToZero();
         mContactConstraints[mNbContactManifolds].frictionPointBody1.setToZero();
@@ -273,24 +272,6 @@ void ContactSolverSystem::initializeForIsland(uint islandIndex) {
         mContactConstraints[mNbContactManifolds].friction2Impulse = externalManifold.frictionImpulse2;
         mContactConstraints[mNbContactManifolds].frictionTwistImpulse = externalManifold.frictionTwistImpulse;
 
-        // Compute the inverse K matrix for the rolling resistance constraint
-        const bool isBody1DynamicType = mRigidBodyComponents.mBodyTypes[rigidBodyIndex1] == BodyType::DYNAMIC;
-        const bool isBody2DynamicType = mRigidBodyComponents.mBodyTypes[rigidBodyIndex2] == BodyType::DYNAMIC;
-        mContactConstraints[mNbContactManifolds].inverseRollingResistance.setToZero();
-        if (mContactConstraints[mNbContactManifolds].rollingResistanceFactor > 0 && (isBody1DynamicType || isBody2DynamicType)) {
-
-            mContactConstraints[mNbContactManifolds].inverseRollingResistance = mContactConstraints[mNbContactManifolds].inverseInertiaTensorBody1 + mContactConstraints[mNbContactManifolds].inverseInertiaTensorBody2;
-            const 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.getInverseWithDeterminant(det);
-            }
-        }
-
         mContactConstraints[mNbContactManifolds].normal.normalize();
 
         // deltaVFrictionPoint = v2 + w2.cross(mContactConstraints[mNbContactManifolds].r2Friction) -
@@ -479,11 +460,6 @@ void ContactSolverSystem::warmStart() {
             // Update the velocities of the body 2 by applying the impulse P
             mRigidBodyComponents.mConstrainedAngularVelocities[rigidBody2Index] += 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
             mRigidBodyComponents.mConstrainedAngularVelocities[rigidBody1Index] -= mContactConstraints[c].inverseInertiaTensorBody1 * angularImpulseBody2;
 
@@ -496,7 +472,6 @@ void ContactSolverSystem::warmStart() {
             mContactConstraints[c].friction1Impulse = 0.0;
             mContactConstraints[c].friction2Impulse = 0.0;
             mContactConstraints[c].frictionTwistImpulse = 0.0;
-            mContactConstraints[c].rollingResistanceImpulse.setToZero();
         }
     }
 }
@@ -781,34 +756,6 @@ void ContactSolverSystem::solve() {
         mRigidBodyComponents.mConstrainedAngularVelocities[rigidBody2Index].x += angularVelocity2.x;
         mRigidBodyComponents.mConstrainedAngularVelocities[rigidBody2Index].y += angularVelocity2.y;
         mRigidBodyComponents.mConstrainedAngularVelocities[rigidBody2Index].z += angularVelocity2.z;
-
-        // --------- 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
-            angularVelocity1 = mContactConstraints[c].inverseInertiaTensorBody1 * deltaLambdaRolling;
-            mRigidBodyComponents.mConstrainedAngularVelocities[rigidBody1Index].x -= angularVelocity1.x;
-            mRigidBodyComponents.mConstrainedAngularVelocities[rigidBody1Index].y -= angularVelocity1.y;
-            mRigidBodyComponents.mConstrainedAngularVelocities[rigidBody1Index].z -= angularVelocity1.z;
-
-            // Update the velocities of the body 2 by applying the impulse P
-            angularVelocity2 = mContactConstraints[c].inverseInertiaTensorBody2 * deltaLambdaRolling;
-            mRigidBodyComponents.mConstrainedAngularVelocities[rigidBody2Index].x += angularVelocity2.x;
-            mRigidBodyComponents.mConstrainedAngularVelocities[rigidBody2Index].y += angularVelocity2.y;
-            mRigidBodyComponents.mConstrainedAngularVelocities[rigidBody2Index].z += angularVelocity2.z;
-        }
     }
 }
 
@@ -833,7 +780,6 @@ void ContactSolverSystem::storeImpulses() {
         mContactConstraints[c].externalContactManifold->frictionImpulse1 = mContactConstraints[c].friction1Impulse;
         mContactConstraints[c].externalContactManifold->frictionImpulse2 = mContactConstraints[c].friction2Impulse;
         mContactConstraints[c].externalContactManifold->frictionTwistImpulse = mContactConstraints[c].frictionTwistImpulse;
-        mContactConstraints[c].externalContactManifold->rollingResistanceImpulse = mContactConstraints[c].rollingResistanceImpulse;
         mContactConstraints[c].externalContactManifold->frictionVector1 = mContactConstraints[c].frictionVector1;
         mContactConstraints[c].externalContactManifold->frictionVector2 = mContactConstraints[c].frictionVector2;
     }

testbed/scenes/concavemesh/ConcaveMeshScene.cpp

@@ -108,9 +108,6 @@ ConcaveMeshScene::ConcaveMeshScene(const std::string& name, EngineSettings& sett
         // Create a sphere and a corresponding rigid in the physics world
         Sphere* sphere = new Sphere(true, SPHERE_RADIUS, mPhysicsCommon, mPhysicsWorld, meshFolderPath);
 
-        // Add some rolling resistance
-        sphere->getCollider()->getMaterial().setRollingResistance(rp3d::decimal(0.08));
-
         // Set the box color
         sphere->setColor(mObjectColorDemo);
         sphere->setSleepingColor(mSleepingColorDemo);
@@ -131,8 +128,6 @@ ConcaveMeshScene::ConcaveMeshScene(const std::string& name, EngineSettings& sett
         Capsule* capsule = new Capsule(true, CAPSULE_RADIUS, CAPSULE_HEIGHT,
                                        mPhysicsCommon, mPhysicsWorld, meshFolderPath);
 
-        capsule->getCollider()->getMaterial().setRollingResistance(rp3d::decimal(0.08));
-
         // Set the box color
         capsule->setColor(mObjectColorDemo);
         capsule->setSleepingColor(mSleepingColorDemo);

testbed/scenes/cubestack/CubeStackScene.cpp

@@ -145,6 +145,8 @@ void CubeStackScene::reset() {
                                   0);
 
             box->setTransform(rp3d::Transform(position, rp3d::Quaternion::identity()));
+            box->getRigidBody()->setLinearVelocity(rp3d::Vector3::zero());
+            box->getRigidBody()->setAngularVelocity(rp3d::Vector3::zero());
 
             index++;
         }

testbed/scenes/heightfield/HeightFieldScene.cpp

@@ -107,9 +107,6 @@ HeightFieldScene::HeightFieldScene(const std::string& name, EngineSettings& sett
         // Create a sphere and a corresponding rigid in the physics world
         Sphere* sphere = new Sphere(true, SPHERE_RADIUS, mPhysicsCommon, mPhysicsWorld, meshFolderPath);
 
-		// Add some rolling resistance
-        sphere->getCollider()->getMaterial().setRollingResistance(0.08f);
-
 		// Set the box color
 		sphere->setColor(mObjectColorDemo);
 		sphere->setSleepingColor(mSleepingColorDemo);
@@ -129,8 +126,6 @@ HeightFieldScene::HeightFieldScene(const std::string& name, EngineSettings& sett
         // Create a cylinder and a corresponding rigid in the physics world
         Capsule* capsule = new Capsule(true, CAPSULE_RADIUS, CAPSULE_HEIGHT, mPhysicsCommon, mPhysicsWorld, meshFolderPath);
 
-        capsule->getCollider()->getMaterial().setRollingResistance(0.08f);
-
 		// Set the box color
 		capsule->setColor(mObjectColorDemo);
 		capsule->setSleepingColor(mSleepingColorDemo);

testbed/scenes/pile/PileScene.cpp

@@ -105,9 +105,6 @@ PileScene::PileScene(const std::string& name, EngineSettings& settings)
         // Create a sphere and a corresponding rigid in the physics world
         Sphere* sphere = new Sphere(true, SPHERE_RADIUS, mPhysicsCommon, mPhysicsWorld, meshFolderPath);
 
-        // Add some rolling resistance
-        sphere->getCollider()->getMaterial().setRollingResistance(rp3d::decimal(0.08));
-
         // Set the box color
         sphere->setColor(mObjectColorDemo);
         sphere->setSleepingColor(mSleepingColorDemo);
@@ -128,8 +125,6 @@ PileScene::PileScene(const std::string& name, EngineSettings& settings)
         Capsule* capsule = new Capsule(true, CAPSULE_RADIUS, CAPSULE_HEIGHT,
                                        mPhysicsCommon, mPhysicsWorld, meshFolderPath);
 
-        capsule->getCollider()->getMaterial().setRollingResistance(rp3d::decimal(0.08f));
-
         // Set the box color
         capsule->setColor(mObjectColorDemo);
         capsule->setSleepingColor(mSleepingColorDemo);