btBvhTriangleMeshShape and collision

[whiplash]

I create "btBvhTriangleMeshShape" collision shape, but my shape don't collising at other collision shape's. My code:

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btTriangleIndexVertexArray* indexVertexArrays = new btTriangleIndexVertexArray(
	m_iTriangles, m_iPoint, 3 * sizeof(int),
	m_iVertices, m_vPoint, 3 * sizeof(float));
btBvhTriangleMeshShape* trimesh = new btBvhTriangleMeshShape(indexVertexArrays, true);

btVector3 inertia(0.0, 0.0, 0.0);
//trimesh->calculateLocalInertia(mass, inertia);

btVector3 pos(0, 300, 0);
btQuaternion rot(0, 0, 0, 1);
btTransform trans(rot, pos);
btTransform centerOfMass = btTransform::getIdentity();	
btDefaultMotionState* mtState = new btDefaultMotionState(trans, centerOfMass);

btRigidBody::btRigidBodyConstructionInfo rbInfo(mass, mtState, trimesh, inertia);
rbInfo.m_additionalDamping = true;
btRigidBody* body = new btRigidBody(rbInfo);

My physic world initialize:

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int maxProxies = 1024;
btVector3 worldAabbMin(-100000.0, -100000.0, -100000.0);
btVector3 worldAabbMax(100000.0, 100000.0, 100000.0);
btAxisSweep3* broadphase = new btAxisSweep3(worldAabbMin, worldAabbMax, maxProxies);
btDefaultCollisionConfiguration* collisionConfiguration = new btDefaultCollisionConfiguration();
btCollisionDispatcher* dispatcher = new btCollisionDispatcher(collisionConfiguration);
btSequentialImpulseConstraintSolver* solver = new btSequentialImpulseConstraintSolver;
dynamicsWorld = new btDiscreteDynamicsWorld(dispatcher, broadphase, solver, collisionConfiguration);

// Ground shape
dynamicsWorld->setGravity(btVector3(0, -9.8, 0));
btCollisionShape* groundShape = new btStaticPlaneShape(btVector3(0, 1, 0), 1);
btDefaultMotionState* groundMotionState = new btDefaultMotionState(btTransform(btQuaternion(0, 0, 0, 1),
	btVector3(0, -1, 0)));
btRigidBody::btRigidBodyConstructionInfo groundRigidBodyCI(0, groundMotionState, groundShape, btVector3(0,0,0));
btRigidBody* groundRigidBody = new btRigidBody(groundRigidBodyCI);
groundRigidBody->setCollisionFlags(groundRigidBody->getCollisionFlags() | btCollisionObject::CF_CUSTOM_MATERIAL_CALLBACK);
groundRigidBody->setFriction(5.0);
groundRigidBody->setRestitution(0.6);
dynamicsWorld->addRigidBody(groundRigidBody);

I need a creating special "btCollisionDispatcher"?

[Erwin Coumans]

btBvhTriangleMeshShape can only be used for static (non-moving, mass=0) world geometry, and there is no collision detection among static artwork.

Generally it is not recommended to use moving concave triangle meshes, but approximate the moving shapes using convex shapes or compounds of convex shapes (btCompoundShape). If you still want to use moving concave triangle meshes, please check out Bullet/Demos/MovingConcaveDemo, and use btGImpactMeshShape.

Thanks,
Erwin

[whiplash]

Thanks! I try it.

[whiplash]

I use btGImpactMeshShape. Collision "btGImpactMeshShape"-"ground" is normal (all position) but collision "btGImpactMeshShape"-"btCapsuleShape" is fail (some position).

fail_col.JPG

Create btGImpactMeshShape:

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const int c_vertex = 8;
const int c_tri = 12;
float vertex[c_vertex * 3] = {
	-20, -50, 20,
	-20, -50, -20,
	20, -50, -20,
	20, -50, 20,
	-20, 50, 20,
	-20, 50, -20,
	20, 50, -20,
	20, 50, 20};
int idx[c_tri * 3] = {
	1, 5, 8,
	1, 8, 4,
	4, 8, 7,
	4, 7, 3,
	3, 7, 6,
	3, 6, 2,
	2, 6, 5,
	2, 5, 1,
	5, 6, 7,
	5, 7, 8,
	2, 1, 4,
	2, 4, 3};

	btTriangleIndexVertexArray* indexVertexArrays = new btTriangleIndexVertexArray(
		c_tri, idx, 3 * sizeof(int),
		c_vertex, vertex, 3 * sizeof(float));
	btGImpactMeshShape* trimesh = new btGImpactMeshShape(indexVertexArrays);
	trimesh->updateBound();

	btScalar mass = 60.0;
	btVector3 inertia(0.0, 0.0, 0.0);
	trimesh->calculateLocalInertia(mass, inertia);

	Vector3 entPos = ph_entities[2]->getParentSceneNode()->_getDerivedPosition();
	Quaternion entRot = ph_entities[2]->getParentSceneNode()->_getDerivedOrientation();

	btVector3 pos(entPos.x, entPos.y, entPos.z);
	btQuaternion rot(entRot.x, entRot.y, entRot.z, entRot.w);
	btTransform trans(rot, pos);
	btTransform centerOfMass = btTransform::getIdentity();			
	btDefaultMotionState* mtState = new btDefaultMotionState(trans, centerOfMass);

	btRigidBody::btRigidBodyConstructionInfo rbInfo(mass, mtState, trimesh, inertia);
	rbInfo.m_additionalDamping = true;

	btRigidBody* body = new btRigidBody(rbInfo);
	dynamicsWorld->addRigidBody(body);

Create btCapsuleShape:

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btCollisionShape* shape = new btCapsuleShape(10.0, 80.0);
	btScalar mass = 10.0;
	btVector3 inertia(0.0, 0.0, 0.0);
	shape->calculateLocalInertia(mass, inertia);

	Vector3 entPos = ph_entities[0]->getParentSceneNode()->_getDerivedPosition();
	Quaternion entRot = ph_entities[0]->getParentSceneNode()->_getDerivedOrientation();

	btVector3 pos(entPos.x, entPos.y, entPos.z);
	btQuaternion rot(entRot.x, entRot.y, entRot.z, entRot.w);
	btTransform trans(rot, pos);
	btDefaultMotionState* mtState = new btDefaultMotionState(trans);

	btRigidBody::btRigidBodyConstructionInfo rbInfo(mass, mtState, shape, inertia);
	rbInfo.m_additionalDamping = true;
	btRigidBody* body = new btRigidBody(rbInfo);

	body->setActivationState(DISABLE_DEACTIVATION);
	body->setCollisionFlags(body->getCollisionFlags() | btCollisionObject::CF_CUSTOM_MATERIAL_CALLBACK);
	//body->setCollisionFlags(body->getCollisionFlags() | btCollisionObject::CF_STATIC_OBJECT);
	body->setFriction(5.0);
	body->setRestitution(0.5);
	dynamicsWorld->addRigidBody(body);

Init physic:

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int maxProxies = 1024;
	btVector3 worldAabbMin(-100000.0, -100000.0, -100000.0);
	btVector3 worldAabbMax(100000.0, 100000.0, 100000.0);
	btAxisSweep3* broadphase = new btAxisSweep3(worldAabbMin, worldAabbMax, maxProxies);
	btDefaultCollisionConfiguration* collisionConfiguration = new btDefaultCollisionConfiguration();
	btCollisionDispatcher* dispatcher = new btCollisionDispatcher(collisionConfiguration);
	dispatcher->setNearCallback(MyNearCallback);
	btSequentialImpulseConstraintSolver* solver = new btSequentialImpulseConstraintSolver;
	dynamicsWorld = new btDiscreteDynamicsWorld(dispatcher, broadphase, solver, collisionConfiguration);

	btCollisionDispatcher* dispatcherGI = static_cast<btCollisionDispatcher*>(dynamicsWorld->getDispatcher());
	btGImpactCollisionAlgorithm::registerAlgorithm(dispatcher);
	
	dynamicsWorld->setGravity(btVector3(0, -9.8, 0));
	btCollisionShape* groundShape = new btStaticPlaneShape(btVector3(0, 1, 0), 1);
	btDefaultMotionState* groundMotionState = new btDefaultMotionState(btTransform(btQuaternion(0, 0, 0, 1),
		btVector3(0, -1, 0)));
	btRigidBody::btRigidBodyConstructionInfo groundRigidBodyCI(0, groundMotionState, groundShape, btVector3(0,0,0));
	btRigidBody* groundRigidBody = new btRigidBody(groundRigidBodyCI);
	groundRigidBody->setCollisionFlags(groundRigidBody->getCollisionFlags() | btCollisionObject::CF_CUSTOM_MATERIAL_CALLBACK);
	groundRigidBody->setFriction(5.0);
	groundRigidBody->setRestitution(0.6);
	dynamicsWorld->addRigidBody(groundRigidBody);