From fa1d1fc8eeb80d8887faea3cb3c83d9abe3c1935 Mon Sep 17 00:00:00 2001 From: Johannes Brust Date: Tue, 28 Sep 2021 22:39:31 +0200 Subject: Add deformable contact forces info - add contact information for collisions between rigid and soft bodies - collisions between different soft bodies are not supported - uses impulse acting on tetrahedral nodes for calculation of forces - contact points are approximated by node positions - multiple forces acting on identical nodes are accumulated (cherry picked from commit 5795bd676f285c5e830218d73181dbf098a03cb4) --- .../SharedMemory/PhysicsServerCommandProcessor.cpp | 232 +++++++++++++-------- 1 file changed, 142 insertions(+), 90 deletions(-) (limited to 'examples') diff --git a/examples/SharedMemory/PhysicsServerCommandProcessor.cpp b/examples/SharedMemory/PhysicsServerCommandProcessor.cpp index 8275451ed..59fd491d3 100644 --- a/examples/SharedMemory/PhysicsServerCommandProcessor.cpp +++ b/examples/SharedMemory/PhysicsServerCommandProcessor.cpp @@ -2802,7 +2802,7 @@ void PhysicsServerCommandProcessor::createEmptyDynamicsWorld(int flags) m_data->m_dynamicsWorld->getSolverInfo().m_frictionERP = 0.2; //need to check if there are artifacts with frictionERP m_data->m_dynamicsWorld->getSolverInfo().m_linearSlop = 0.00001; m_data->m_dynamicsWorld->getSolverInfo().m_numIterations = 50; - if (flags & RESET_USE_REDUCED_DEFORMABLE_WORLD) + if (flags & RESET_USE_REDUCED_DEFORMABLE_WORLD) { m_data->m_dynamicsWorld->getSolverInfo().m_minimumSolverBatchSize = 128; } @@ -5677,7 +5677,7 @@ bool PhysicsServerCommandProcessor::processRequestMeshDataCommand(const struct S separateRenderMesh = (psb->m_renderNodes.size() != 0); } bool requestVelocity = clientCmd.m_updateFlags & B3_MESH_DATA_SIMULATION_MESH_VELOCITY; - + int numVertices = separateRenderMesh ? psb->m_renderNodes.size() : psb->m_nodes.size(); int maxNumVertices = bufferSizeInBytes / totalBytesPerVertex - 1; int numVerticesRemaining = numVertices - clientCmd.m_requestMeshDataArgs.m_startingVertex; @@ -8187,7 +8187,7 @@ bool PhysicsServerCommandProcessor::processRequestActualStateCommand(const struc } bool RequestFiltered(const struct SharedMemoryCommand& clientCmd, int& linkIndexA, int& linkIndexB, int& objectIndexA, int& objectIndexB, bool& swap){ - + if (clientCmd.m_requestContactPointArguments.m_objectAIndexFilter >= 0) { if (clientCmd.m_requestContactPointArguments.m_objectAIndexFilter == objectIndexA) @@ -8232,7 +8232,7 @@ bool RequestFiltered(const struct SharedMemoryCommand& clientCmd, int& linkIndex { return true; } - + return false; } @@ -8313,115 +8313,167 @@ bool PhysicsServerCommandProcessor::processRequestDeformableContactpointHelper(c { return false; } - int numSoftbodyContact = 0; - for (int i = deformWorld->getSoftBodyArray().size() - 1; i >= 0; i--) - { - numSoftbodyContact += deformWorld->getSoftBodyArray()[i]->m_faceRigidContacts.size(); - } - int num_contact_points = m_data->m_cachedContactPoints.size(); - m_data->m_cachedContactPoints.reserve(num_contact_points + numSoftbodyContact); for (int i = deformWorld->getSoftBodyArray().size() - 1; i >= 0; i--) { btSoftBody* psb = deformWorld->getSoftBodyArray()[i]; + btAlignedObjectArray distinctContactPoints; + btAlignedObjectArray nodesInContact; for (int c = 0; c < psb->m_faceRigidContacts.size(); c++) { const btSoftBody::DeformableFaceRigidContact* contact = &psb->m_faceRigidContacts[c]; - //convert rigidbody contact - int linkIndexA = -1; - int linkIndexB = -1; - int objectIndexA = psb->getUserIndex2(); - - int objectIndexB = -1; - const btRigidBody* bodyB = btRigidBody::upcast(contact->m_cti.m_colObj); - if (bodyB) - { - objectIndexB = bodyB->getUserIndex2(); - } - const btMultiBodyLinkCollider* mblB = btMultiBodyLinkCollider::upcast(contact->m_cti.m_colObj); - if (mblB && mblB->m_multiBody) - { - linkIndexB = mblB->m_link; - objectIndexB = mblB->m_multiBody->getUserIndex2(); - } + // calculate normal and tangent impulse + btVector3 impulse = contact->m_cti.m_impulse; + btVector3 impulseNormal = impulse.dot(contact->m_cti.m_normal) * contact->m_cti.m_normal; + btVector3 impulseTangent = impulse - impulseNormal; + // get node in contact + int contactNodeIdx = contact->m_bary.maxAxis(); + btSoftBody::Node* node = contact->m_face->m_n[contactNodeIdx]; + // check if node is already in the list + int idx = nodesInContact.findLinearSearch2(node); + if (idx < 0) + { + // add new node and contact point + nodesInContact.push_back(node); + //convert rigidbody contact + int linkIndexA = -1; + int linkIndexB = -1; + int objectIndexA = psb->getUserIndex2(); - //apply the filter, if the user provides it - bool swap = false; - if (clientCmd.m_requestContactPointArguments.m_objectAIndexFilter >= 0) - { - if (clientCmd.m_requestContactPointArguments.m_objectAIndexFilter == objectIndexA) + int objectIndexB = -1; + const btRigidBody* bodyB = btRigidBody::upcast(contact->m_cti.m_colObj); + if (bodyB) { - swap = false; + objectIndexB = bodyB->getUserIndex2(); } - else if (clientCmd.m_requestContactPointArguments.m_objectAIndexFilter == objectIndexB) + const btMultiBodyLinkCollider* mblB = btMultiBodyLinkCollider::upcast(contact->m_cti.m_colObj); + if (mblB && mblB->m_multiBody) { - swap = true; + linkIndexB = mblB->m_link; + objectIndexB = mblB->m_multiBody->getUserIndex2(); } - else + + //apply the filter, if the user provides it + bool swap = false; + if (clientCmd.m_requestContactPointArguments.m_objectAIndexFilter >= 0) { - continue; + if (clientCmd.m_requestContactPointArguments.m_objectAIndexFilter == objectIndexA) + { + swap = false; + } + else if (clientCmd.m_requestContactPointArguments.m_objectAIndexFilter == objectIndexB) + { + swap = true; + } + else + { + continue; + } } - } - if (swap) - { - std::swap(objectIndexA, objectIndexB); - std::swap(linkIndexA, linkIndexB); - } + if (swap) + { + std::swap(objectIndexA, objectIndexB); + std::swap(linkIndexA, linkIndexB); + } - //apply the second object filter, if the user provides it - if (clientCmd.m_requestContactPointArguments.m_objectBIndexFilter >= 0) - { - if (clientCmd.m_requestContactPointArguments.m_objectBIndexFilter != objectIndexB) + //apply the second object filter, if the user provides it + if (clientCmd.m_requestContactPointArguments.m_objectBIndexFilter >= 0) { - continue; + if (clientCmd.m_requestContactPointArguments.m_objectBIndexFilter != objectIndexB) + { + continue; + } } - } - if ( - (clientCmd.m_updateFlags & CMD_REQUEST_CONTACT_POINT_HAS_LINK_INDEX_A_FILTER) && - clientCmd.m_requestContactPointArguments.m_linkIndexAIndexFilter != linkIndexA) - { - continue; - } + if ( + (clientCmd.m_updateFlags & CMD_REQUEST_CONTACT_POINT_HAS_LINK_INDEX_A_FILTER) && + clientCmd.m_requestContactPointArguments.m_linkIndexAIndexFilter != linkIndexA) + { + continue; + } - if ( - (clientCmd.m_updateFlags & CMD_REQUEST_CONTACT_POINT_HAS_LINK_INDEX_B_FILTER) && - clientCmd.m_requestContactPointArguments.m_linkIndexBIndexFilter != linkIndexB) - { - continue; - } - b3ContactPointData pt; - pt.m_bodyUniqueIdA = objectIndexA; - pt.m_bodyUniqueIdB = objectIndexB; - pt.m_contactDistance = contact->m_cti.m_offset; - pt.m_contactFlags = 0; - pt.m_linkIndexA = linkIndexA; - pt.m_linkIndexB = linkIndexB; - for (int j = 0; j < 3; j++) - { - if (swap) + if ( + (clientCmd.m_updateFlags & CMD_REQUEST_CONTACT_POINT_HAS_LINK_INDEX_B_FILTER) && + clientCmd.m_requestContactPointArguments.m_linkIndexBIndexFilter != linkIndexB) { - pt.m_contactNormalOnBInWS[j] = -contact->m_cti.m_normal[j]; - pt.m_positionOnAInWS[j] = contact->m_cti.m_normal[j]; - pt.m_positionOnBInWS[j] = -contact->m_cti.m_normal[j]; + continue; } - else + b3ContactPointData pt; + pt.m_bodyUniqueIdA = objectIndexA; + pt.m_bodyUniqueIdB = objectIndexB; + pt.m_contactDistance = -contact->m_cti.m_offset; + pt.m_contactFlags = 0; + pt.m_linkIndexA = linkIndexA; + pt.m_linkIndexB = linkIndexB; + for (int j = 0; j < 3; j++) { - pt.m_contactNormalOnBInWS[j] = contact->m_cti.m_normal[j]; - pt.m_positionOnAInWS[j] = -contact->m_cti.m_normal[j]; - pt.m_positionOnBInWS[j] = contact->m_cti.m_normal[j]; + if (swap) + { + pt.m_contactNormalOnBInWS[j] = -contact->m_cti.m_normal[j]; + pt.m_positionOnAInWS[j] = node->m_x[j] - pt.m_contactDistance * pt.m_contactNormalOnBInWS[j]; // not really precise because of margins in btSoftBody.cpp:line 2912 + // node is force application point, therefore node position is contact point (not contact->m_contactPoint, because not equal to node) + pt.m_positionOnBInWS[j] = node->m_x[j]; + } + else + { + pt.m_contactNormalOnBInWS[j] = contact->m_cti.m_normal[j]; + // node is force application point, therefore node position is contact point (not contact->m_contactPoint, because not equal to node) + pt.m_positionOnAInWS[j] = node->m_x[j]; + pt.m_positionOnBInWS[j] = node->m_x[j] - pt.m_contactDistance * pt.m_contactNormalOnBInWS[j]; // not really precise because of margins in btSoftBody.cpp:line 2912 + } + } + pt.m_normalForce = (impulseNormal / m_data->m_physicsDeltaTime).norm(); + pt.m_linearFrictionForce1 = (impulseTangent.dot(contact->t1) * contact->t1 / m_data->m_physicsDeltaTime).norm(); + pt.m_linearFrictionForce2 = (impulseTangent.dot(contact->t2) * contact->t2 / m_data->m_physicsDeltaTime).norm(); + for (int j = 0; j < 3; j++) + { + pt.m_linearFrictionDirection1[j] = contact->t1[j]; + pt.m_linearFrictionDirection2[j] = contact->t2[j]; } + distinctContactPoints.push_back(pt); } - pt.m_normalForce = 1; - pt.m_linearFrictionForce1 = 0; - pt.m_linearFrictionForce2 = 0; - for (int j = 0; j < 3; j++) + else { - pt.m_linearFrictionDirection1[j] = 0; - pt.m_linearFrictionDirection2[j] = 0; + // add values to existing contact point + b3ContactPointData* pt = &distinctContactPoints[idx]; + // current normal force of node + btVector3 normalForce = btVector3(btScalar(pt->m_contactNormalOnBInWS[0]), + btScalar(pt->m_contactNormalOnBInWS[1]), + btScalar(pt->m_contactNormalOnBInWS[2])) * pt->m_normalForce; + // add normal force of additional node contact + normalForce += contact->m_cti.m_normal * (impulseNormal / m_data->m_physicsDeltaTime).norm(); + // get magnitude of normal force + pt->m_normalForce = normalForce.norm(); + // get direction of normal force + if (!normalForce.fuzzyZero()) + { + // normalize for unit vectors if above numerical threshold + normalForce.normalize(); + for (int j = 0; j < 3; j++) + { + pt->m_contactNormalOnBInWS[j] = normalForce[j]; + } + } + + // add magnitudes of tangential forces in existing directions + btVector3 linearFrictionDirection1 = btVector3(btScalar(pt->m_linearFrictionDirection1[0]), + btScalar(pt->m_linearFrictionDirection1[1]), + btScalar(pt->m_linearFrictionDirection1[2])); + btVector3 linearFrictionDirection2 = btVector3(btScalar(pt->m_linearFrictionDirection2[0]), + btScalar(pt->m_linearFrictionDirection2[1]), + btScalar(pt->m_linearFrictionDirection2[2])); + pt->m_linearFrictionForce1 = (impulseTangent.dot(linearFrictionDirection1) * linearFrictionDirection1 / m_data->m_physicsDeltaTime).norm(); + pt->m_linearFrictionForce2 = (impulseTangent.dot(linearFrictionDirection2) * linearFrictionDirection2 / m_data->m_physicsDeltaTime).norm(); } - m_data->m_cachedContactPoints.push_back(pt); + } + + int num_contact_points = m_data->m_cachedContactPoints.size() + distinctContactPoints.size(); + m_data->m_cachedContactPoints.reserve(num_contact_points); + // add points to contact points cache + for (int p = 0; p < distinctContactPoints.size(); p++) + { + m_data->m_cachedContactPoints.push_back(distinctContactPoints[p]); } } #endif @@ -9929,7 +9981,7 @@ bool PhysicsServerCommandProcessor::processReducedDeformable(const UrdfReducedDe softWorld->addSoftBody(rsb); } } - + *bodyUniqueId = m_data->m_bodyHandles.allocHandle(); InternalBodyHandle* bodyHandle = m_data->m_bodyHandles.getHandle(*bodyUniqueId); bodyHandle->m_softBody = rsb; @@ -9980,7 +10032,7 @@ bool PhysicsServerCommandProcessor::processReducedDeformable(const UrdfReducedDe float scaling[4] = { 1,1,1,1 }; int instanceUid = m_data->m_guiHelper->registerGraphicsInstance(shapeUid1, position, orientation, color, scaling); rsb->setUserIndex(instanceUid); - + if (m_data->m_enableTinyRenderer) { int texUid2 = m_data->m_pluginManager.getRenderInterface()->registerTexture(meshData.m_textureImage1, meshData.m_textureWidth, meshData.m_textureHeight); @@ -10080,7 +10132,7 @@ bool PhysicsServerCommandProcessor::processReducedDeformable(const UrdfReducedDe } } } - + btAlignedObjectArray vertices; @@ -10093,7 +10145,7 @@ bool PhysicsServerCommandProcessor::processReducedDeformable(const UrdfReducedDe for (int i = 0; i < rsb->m_faces.size(); i++) // Foreach face { - + for (int k = 0; k < 3; k++) // Foreach vertex on a face { int currentIndex = i * 3 + k; -- cgit v1.2.1