[X3D-Public] Multiple Materials for Geometry (IndexedFaceSet)

[Dave A]

As he said, and I said, yes, break the mesh up. One Appearance per mesh 
(IFS) is all you get. So break it up by material/texture (in effect, 
Appearance), and then Group the parts is your best bet. Doing that 
per-vertex color thing is more work than it's worth for blandly-simple 
objects.
And note that if there are light maps, bump maps, etc. (MultiTexture) 
you need to account for those as well. I would sort all polygons sharing 
the same Appearance into the SAME (sub)mesh, rather than creating 
separate polygons, where ever possible.

Dave A.

On 1/4/2011 6:04 PM, JOHN COADY wrote:
> Does anyone from the web3d community have any ideas on how best to 
> handle this issue when converting from blender to X3D. Blender 
> supports multiple materials per object whereas X3D only supports a 
> single material per shape in an appearance node. For example, in 
> blender if you have a cube shaped object, you can assign a different 
> material to each of the 6 faces of the cube. When exporting this 
> object from blender into X3D the object is converted into a shape with 
> an IndexedFaceSet and an appearance node with a single material. Only 
> one of the 6 materials from the blender cube shaped object can be 
> assigned to the indexedFaceSet cubed shaped object in X3D. The blender 
> developer is suggesting to break up the cube shaped object from 
> blender and creating 6 separate IndexedFaceSet objects in X3D, one for 
> each face of the cube, so that he can assign a unique material to each 
> of the 6 faces. Is this a good idea? He wants to do the same thing if 
> there are multiple textures on the object in blender. The other way to 
> handle it is to use the color field of the indexed face set and assign 
> a color to each of the faces in X3D from the diffuse color of the 
> material in blender for that face.
>
> ----- Original Message -----
> From: Dave A <dave at realmofconcepts.com>
> Date: Tuesday, January 4, 2011 5:28 pm
> Subject: Re: [X3D-Public] Multiple Materials for Geometry (IndexedFaceSet)
> To: Campbell Barton <ideasman42 at gmail.com>, X3D-Public at web3d.org
>
> > I think you need to break the mesh into pieces (then put them in
> > a Group) because you can have only one Appearance per mesh.
> >
> > "Campbell Barton" <ideasman42 at gmail.com> wrote:
> >
> > >Hi, I'm currently making some updates to blender 2.5'x X3D exporter,
> > >since we have a diligent user reporting all sorts of bugs.
> > >
> > >One problem I've hit is that it seems there is no way to have
> > >different materials for one mesh.
> > >
> > >There are some ways that have been suggested but I find both
> > >unsatisfactory.
> > >
> > >1) Set colorPerVertex="false", then define color per face.
> > >This is no good because you may have different specular, diffuse
> > >values per material (not just color)
> > >
> > >2) Use MultiTexture?, This was suggested but from what I can
> > tell its
> > >only for layering textures, not applying different textures to
> > >different parts of the mesh.
> > >
> > >The things Id like to support are:
> > >- Different images on the same mesh.
> > >- Different material's on the same mesh.
> > >
> > >From what I can tell there is no way to do this so as a last resort
> > >the exporter could split the object's materials into multiple
> > objects,>which is not ideal but I cant see an alternative.
> > >
> > >Am I missing something?.
> > >
> > >--
> > >- Campbell
> > >
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> >
> > --
> > Sent from my Android phone with K-9 Mail. Please excuse my brevity.
> >
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