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vfgdfg

Total Points:
560
Status Points:
60

Brown Belt

October 12, 2008 2:19 PM PDT

hkpSimpleMeshShape won't come to rest

Hey,

first of all thanks for Intel making Havok available like this. And this forum seems really great.

I've got a problem I hope you could help with. I've done a simple test project that creates two hkpSimpleMeshShapes (just boxes) from my mesh triangle data, and they appear to form correctly in the Visual Debugger, but when the box drops on the another one and is supposed to settle in to rest, it instead jumps away.

With worldInfo.m_contactRestingVelocity = 0.01f, it is even crazier.

This is what I have in worldInfo:

		worldInfo.m_gravity.set(0.0f, -9.8f, 0.0f);
		worldInfo.setupSolverInfo(hkpWorldCinfo::SOLVER_TYPE_8ITERS_MEDIUM); 
		worldInfo.m_collisionTolerance = 0.01f;
		//worldInfo.m_contactRestingVelocity = 0.01f;

This is how I create the boxes:

	// Create the floor as a fixed box
	{
		hkpRigidBodyCinfo boxInfo;

		hkpSimpleMeshShape* shape2 = new hkpSimpleMeshShape( 0.1f ); 

		shape2->m_vertices.setSize( mesh2.numVertices ); 

		for(int i=0; i<mesh2.numVertices; i++)
		{
			//sprintf(str, "vertex %i: %f, %f, %f", i, mesh2.vertexList[i].p.x, mesh2.vertexList[i].p.y, mesh2.vertexList[i].p.z); cprint(str);

			shape2->m_vertices[i].set(
			mesh2.vertexList[i].p.x,
			mesh2.vertexList[i].p.y,
			mesh2.vertexList[i].p.z,
			0.0f );
		}

		//sprintf(str, "numfaces: %i", mesh.numFaces); cprint(str);

		shape2->m_triangles.setSize( mesh.numFaces );

		for(int i=0, k=0; k<mesh2.numFaces; i+=3, k++)
		{
			//sprintf(str, "faces %i: %i, %i, %i", k, mesh2.faceList[i], mesh2.faceList[i+1], mesh2.faceList[i+2]); cprint(str);

			shape2->m_triangles[k].m_a = mesh2.faceList[i+2];
			shape2->m_triangles[k].m_b = mesh2.faceList[i+1];
			shape2->m_triangles[k].m_c = mesh2.faceList[i+0];
		} 

		{
			hkpMoppCompilerInput mci;
			hkpMoppCode *moppCode = hkpMoppUtility::buildCode( shape2, mci );
			hkpMoppBvTreeShape* moppShape = new hkpMoppBvTreeShape( shape2, moppCode );
			shape2->computeWeldingInfo( moppShape, hkpWeldingUtility::WeldingType::WELDING_TYPE_ANTICLOCKWISE );
			moppCode->removeReference();
		}

		boxInfo.m_shape = shape2;
		boxInfo.m_motionType = hkpMotion::MOTION_FIXED;
		boxInfo.m_position.set(0.0f, 0.0f, 0.0f);
		boxInfo.m_restitution = 0.9f;

		g_floor = new hkpRigidBody(boxInfo);
		shape2->removeReference();

		physicsWorld->addEntity(g_floor);
		g_floor->removeReference();
	}

	// Create a moving box
	hkpSimpleMeshShape* shape = new hkpSimpleMeshShape( 0.1f ); 

	shape->m_vertices.setSize( mesh.numVertices ); 

	for(int i=0; i<mesh.numVertices; i++)
	{
		shape->m_vertices[i].set(
		mesh.vertexList[i].p.x,
		mesh.vertexList[i].p.y,
		mesh.vertexList[i].p.z,
		0.0f );
	}

	shape->m_triangles.setSize( mesh.numFaces );

	for(int i=0, k=0; k<mesh.numFaces; i+=3, k++)
	{
		shape->m_triangles[k].m_a = mesh.faceList[i+0];
		shape->m_triangles[k].m_b = mesh.faceList[i+1];
		shape->m_triangles[k].m_c = mesh.faceList[i+2];
	} 

	{
		hkpMoppCompilerInput mci;
		hkpMoppCode *moppCode = hkpMoppUtility::buildCode( shape, mci );
		hkpMoppBvTreeShape* moppShape = new hkpMoppBvTreeShape( shape, moppCode );
		shape->computeWeldingInfo( moppShape, hkpWeldingUtility::WeldingType::WELDING_TYPE_ANTICLOCKWISE );
		moppCode->removeReference();
	}

	const hkReal boxDim = 15.0f;				// This is the size of the cubes
	const hkReal extBoxDim = 1.1f * boxDim;	// This is an extended size (used to shorten the pendulums)
	
	hkVector4 boxRadii(boxDim *.5f, boxDim *.5f, boxDim *.5f);
	hkpShape* boxShape = new hkpBoxShape( boxRadii , 0 ); 
	hkpMassProperties massProperties;
	hkpInertiaTensorComputer::computeBoxVolumeMassProperties(boxRadii, 110.0f, massProperties);

	hkpRigidBodyCinfo boxInfo;

	boxInfo.m_inertiaTensor = massProperties.m_inertiaTensor;
	boxInfo.m_mass = massProperties.m_mass;
	boxInfo.m_shape = shape;
	//boxInfo.m_shape = boxShape;
	boxInfo.m_qualityType = HK_COLLIDABLE_QUALITY_CRITICAL;
	boxInfo.m_motionType = hkpMotion::MOTION_BOX_INERTIA;


	boxInfo.m_position.set(0.0f, 30.0f, -2.0f);


	// Create RigidBody
	hkpRigidBody* RigidBody = new hkpRigidBody(boxInfo);
	shape->removeReference();

	physicsWorld->addEntity(RigidBody);

    g_ball = RigidBody;

	RigidBody->removeReference();

Also I have another test project that creates a vehicle chassis with the same method, and the floor like this:

	// Create the floor as a fixed box
	{
		hkpRigidBodyCinfo boxInfo;
		hkVector4 boxSize(50.0f, 2.5f , 50.0f);
		hkpBoxShape* boxShape = new hkpBoxShape(boxSize);
		boxInfo.m_shape = boxShape;
		boxInfo.m_motionType = hkpMotion::MOTION_FIXED;
		boxInfo.m_position.set(0.0f, 0.0f, 0.0f);
		boxInfo.m_restitution = 0.9f;

		hkpRigidBody* floor = new hkpRigidBody(boxInfo);
		boxShape->removeReference();

		physicsWorld->addEntity(floor);
		floor->removeReference();
	}

The behaviour is again quite strange. Download this Visual Debugger movie file test.hkm to see.

If I create just a normal hkpBoxShape instead of hkpSimpleMeshShape, it settles on the ground nicely.

Sorry this was a lot of text, but hopefully you could provide some assistance.

Best Regards,

vfgdfg

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