Connecting graphics & physics objects with motionstate

[damiench]

Hi,

I am loading my physics object from a collada file using class ColladaConverte.
I am now facing the problem of connecting those physics object to my graphics objects.

I already derive the class ColladaConverte to MyColladaConverter in order to override "createRigidBody".

I also derive btMotionState to MyMotionState following the Ogre3d motion state example from Bullet SDK manual. (Although I am not using Ogre3d).

I understand that it is in my class MyMotionState that I can connect the graphics and physics objects of the scene. As in the Ogre3d example (again I am not using Ogre3d), I can add a member which is a node to one of my graphics objects.

My problem is the following:
I don't know how to retrieve the correct graphics object.
I was hopping to use the rigid_body's attribute name from my collada *.dae file since it is also with that name that my graphics objects are labelled.
What I have in my collada file is such as:
<rigid_body sid="Actor0-RigidBody" name="Boîte01">

How can I retrieve that "name" information inside the method "createRigidBody" that I override?

My question could be reformulate to, while using ColladaConveter and the Ogre3d motion state example, how to specify the correct ogre::scenenode that linked a physics object defined in the collada file and a graphics object (which have a similar name).

Cheers,

Thank you

[Erwin Coumans]

ColladaDemo, BulletColladaConverter, COLLADA_DOM and the Maya Dynamica plugin has been moved to http://dynamica.googlecode.com

The updated BulletColladaConverter has a new virtual method that passes on the target node name. Can you check it?

Code: Select all

///createNamedRigidBody default implementation will call createRigidBody
	///bodyName is the name of the target node (graphics object/node) for example "Cube_015" in
	///<instance_physics_model url="#Cube_015-PhysicsModel">
	///<instance_rigid_body body="Cube_015-RigidBody" target="#Cube_015"/>
	virtual btRigidBody*  createNamedRigidBody(bool isDynamic, 
		float mass, 
		const btTransform& startTransform,
		btCollisionShape* shape, const char* targetNodeName);

What modeler are you using to export the COLLADA file? Perhaps you want to switch to the new .bullet format?
Thanks,
Erwin

[damiench]

The updated BulletColladaConverter has a new virtual method that passes on the target node name. Can you check it?

Hum... I not sure it will help.
First, I don't have Maya, so the Cmake don't execute as it (which is normal!).
Second, my collada file is different than:

Code: Select all

///bodyName is the name of the target node (graphics object/node) for example "Cube_015" in
   ///<instance_physics_model url="#Cube_015-PhysicsModel">
   ///<instance_rigid_body body="Cube_015-RigidBody" target="#Cube_015"/>

The problem I guess comes from the modeler/exporter I am using.
I am using 3dsmax and using the PhysX exporter.
http://supportcenteronline.com/ics/supp ... erID=24981
I know Bullet only support Blender & Maya, but I would expect it support also PhysX because Collada is a standard.
In fact the exporter works, I can load and display the physics geometry.
The hard problem is to connect my graphical nodes to the physical object with motionstate.

I am not sure PhysX exporter really follow the standard (it should).

Anyway, what I need is to be able to acces the attribute "name" of the physical model (not the physical instance):

Code: Select all

<physics_model id="Scene0-PhysicsModel">
		<rigid_body	sid="Actor0-RigidBody" name="Boîte01">
		<instance_geometry url="#ConvexMesh_0-Mesh"/>

Because that name is also the name of my graphical nodes.
I guess, I am assuming that there is one and only one physical instance of that physical model (which is not really good, but fit my case).

I succeed to some results by changing the class ColladaConverter to fit my needs.
Before calling "PreparePhysicsObject(", I force "input.m_bodyName" to another name.

It works so far.