Bulletphysics and osg::Node

[addict]

Hi

I made a osg::Node (osg::Group) with Physics. This works great if i insert the node on position (0,0,0)
If i made a positionattitudeTransform with the physics-Node the node is on the new position but the physics-Node / Object is still at 0,0,0

here is the code:
h-File:

Code: Select all

class PhysicsCube :
			public osg::Group
		{
		public:
			PhysicsCube();
			~PhysicsCube(void);
			osg::MatrixTransform* createNode(double length, double mass, btDynamicsWorld* dynamicsWorld, osg::Vec3d position);
			void setColor(osg::Vec4d color);
			btRigidBody *getBody(void);

		private:
			void createGeometry(void);
			osg::ShapeDrawable* _boxDrawable;
			double _length;
			double _mass;
			btDynamicsWorld* _dynamicsWorld;
			btRigidBody* _body;
		};

		class BallUpdateCallback : public osg::NodeCallback
		{
		private:
			btRigidBody *_body;

		public:
			BallUpdateCallback(btRigidBody *body) :
			  _body(body)
			  {}

			  virtual void operator()(osg::Node* node, osg::NodeVisitor* nv)
			  {
				  btScalar m[16];

				  btDefaultMotionState* myMotionState = ( btDefaultMotionState*)_body->getMotionState();
				  myMotionState->m_graphicsWorldTrans.getOpenGLMatrix(m);

					double t = nv->getFrameStamp()->getReferenceTime();
					osg::Matrix mat = osg::computeLocalToWorld(nv->getNodePath());


				  //osg::Matrixf mat(m);

				  osg::PositionAttitudeTransform *pat = dynamic_cast<osg::PositionAttitudeTransform *>(node);
				  pat->setPosition(mat.getTrans());
				  pat->setAttitude(mat.getRotate());

				  I3D_LOG(notification) << mat.getTrans().x() << ", " << mat.getTrans().y() << ", " << mat.getTrans().z() << std::endl;

				  traverse(node, nv);
			  }
		};

cpp:

Code: Select all

osg::MatrixTransform* PhysicsCube::createNode(double length, double mass, btDynamicsWorld* dynamicsWorld, osg::Vec3d position)
{

	_length = length;
	_mass = mass;
	_dynamicsWorld = dynamicsWorld;

	position = osg::Vec3d(0,0,0);
	
	// OSG CODE
	osg::ref_ptr< osg::MatrixTransform > node = new osg::MatrixTransform;
	

	osg::Geode* geodeBox = new osg::Geode();

	osg::Box* box = new osg::Box(position, _length );
	_boxDrawable = new osg::ShapeDrawable(box);

	_boxDrawable->setColor(osg::Vec4d(0.5, 0.5, 1.0, 1.0));

	geodeBox->addDrawable(_boxDrawable);

	node->addChild(geodeBox);

	// OSGBBULLET CODE
	osgbBullet::MotionState * motion = new osgbBullet::MotionState;
	motion->setTransform( node.get() );
	btCollisionShape * collision = osgbBullet::btConvexTriMeshCollisionShapeFromOSG( node.get() );

	
	// BULLET CODE
	btTransform bodyTransform;
	bodyTransform.setIdentity();
	bodyTransform.setOrigin( btVector3( 0, 0, 0 ) );
	motion->setWorldTransform( bodyTransform );

	btScalar objectMass( mass );
	btVector3 inertia;
	collision->calculateLocalInertia( objectMass, inertia );
	btRigidBody::btRigidBodyConstructionInfo rbinfo( objectMass, motion, collision, inertia );
	 _body = new btRigidBody( rbinfo );
	//   body->setLinearVelocity( btVector3( -5, -1, 0 ) );
	//  body->setAngularVelocity( btVector3( 1, 0, 0 ) );
	dynamicsWorld->addRigidBody(_body );


	return( node.release() );
}

void PhysicsCube::createGeometry(void)
{
}

void PhysicsCube::setColor( osg::Vec4d color )
{
	_boxDrawable->setColor(color);
}

btRigidBody * PhysicsCube::getBody( void )
{
	return _body;
}

I use the physicsCube like this:

Code: Select all

_cNode = new I3DENGINE::Physics::PhysicsCube;
osg::PositionAttitudeTransform *temp = new osg::PositionAttitudeTransform;
temp->addChild(_cNode->createNode(length, mass, dynamicsWorld, position));
temp->addChild(_sNode);

temp->setPosition(osg::Vec3d(0,0,100)); // <- does not work correctly

temp->setUpdateCallback(new I3DENGINE::Physics::BallUpdateCallback(_cNode->getBody()));
return temp;

What has to be changed so that the node's position will be updated according to the physic's node location?
Sorry for my bad english!
Thanks!

[Erwin Coumans]

It is best to update the body transform using body->setWorldTransform(trans), and not using the motionstate.

The motion state is only for initialization and for updates from body->motionstate (graphics), not the other way around (except for kinematic animated objects).

Thanks,
Erwin