Horde3D

Hello,
I'm new to Horde so be gentle .

I'm having some problems with objects that are attached to a character (such as helmet or glasses) importing correctly.

I believe the problem lies in Collada Conv, but I may easily be wrong.

I am using Max and the FCollada exporter. Some attachments work and others do not.

When I export an attachment that works correctly the collada is of the form:

An example of exported Collada that does not work:

In the second example the mesh is attached directly to the Joint. I'm not entirely sure why this happens to some objects in Max (the source art isn't mine), however I believe it is valid. I also think that having an instance geometry directly attached to a joint node is valid in the collada schema.

Assuming that the fault isn't with the data or the collada exporter, then the point at which the geometry is ignored is during the conversion process.

In Converter::convertModel() the assumption is made that a joint cannot contain mesh data.

Removing the "else" from above means that my attachments will be displayed on the model. However I don't imagine this is the correct fix.

What is the correct way to fix this problem?
Is it best fixed in the source data, or the converter?

Thanks,
Sean

Hi blue,

I had a look at the COLLADA spec and both cases you describe seem to be valid. Even worse I noticed that in theory a node could have several instanced geometries. ColladaConv currently ignores that. Your current fix usually won't work correctly since it is discarding the joint.

Obvoiusly instance_geometry is also handled as a scene node in COLLADA, not just as a link, but with limited capabilites (can't have transformation or children). So it always needs some parent node container.

Hmm, one solution would be to always treat instance_geometry as Horde-Mesh-node and COLLADA-node as Group. But this would usually be quite inefficient since it introduces much more nodes than actually required.

I would be interested in knowing how the second case (geometry directly at joint) is looking in the 3ds max schematic view as opposed to the first (usual) case. Do you see any difference there?

Hi Marciano,
I'm not seeing any difference at all in the schematic view.

In the image below you should be able to see glasses and helmet which contain geometry directly at the joint, and eyes which do not.

Thanks for the image. What happens if you also display the Controllers? Do all objects have a Transform controller?

Yup, all the objects have Transform controllers as well.

If you look at your skin modifier, is it true that glasses and helmet are in the joint list and eyes are not? If that's the case it would explain the behavior of ColladaMax. Because then you would have geometry which acts at the same time as a joint, something that is not supported in Horde (nodes are either meshes or joints). But this should be very easy to fix in the model.

Hi Marciano,
Thanks for your help so far. I'm new to 3ds Max and using a resource that wasn't made by me, so you'll have to forgive my ignorance. I have been unable to find the answers on the internet, so perhaps you can help again .

Where can I see the joint list for a skinned model in 3ds Max? What defines what will be exported as a Joint in Collada? How do I determine or change if some geometry is acting as a Joint?

The model is using the Physique modifier, which I think is the basically the skin modifier. I can't see how to get a list of joints from this, and I don't know how to set a geometry to be a joint, or a child of a joint.

I would have thought that the joint came from using the "select and link" to link geometries to the biped. I must be missing something though as that doesn't solve the problem.

Hope you can help. I'm sure if I knew Max better, this would be very obvious.

Thanks,
Sean

The skin modifier has a list of bones (where you can add and remove items) that are used for skinning in the modifier paramters. If you add a mesh to that list it is also exported as a joint, otherwise not. Unfortunately I don't know how things are working when you are using the physique modifier.

I'm happy to announce that all the problems described in this thread should be solved with the next version of ColladaConv. It can handle an arbitrary number of instances and you can also have geometry at a joint now. Furthermore I have cleaned up the node and animation handling code so it should be much easier to understand and modify.