Problem with material reuse in colladaloader2.js

[BengtGustafsson]

Description of the problem

I use a tool called OarConv which produces collada files with multiple <polylist> elements in one <mesh> refering to the same material. This works in colladaloader but in colladaloader2 there seems to be a design flaw that the return value of buildGeometry() is a group which is a map indexed by the material name and which contains just one THREE.Mesh (or similar) object per material name, so when the function runs it overwrites the preceeding 's representation with the succeding one.

I am not totally convinced that this Collada is within the specification but it seems logical that you can have multiple s with the same material and these colladas load in blender and 3ds max and unity.

As this is an architectural level issue I don't see a possibility for me to fix it, there is no easy patch that can be done. I was thinking about uniquifying the material name and duplicating the definition but that was too much of a hack for me to bear...

oar_house.txt

Attached .txt file is actually a dae file.

Three.js version

• [x ] Dev (also tried r74 but the code looks the same)
• r81
• ...

Browser

• All of them (obviously)
• Chrome
• Firefox
• Internet Explorer

OS

• All of them
• Windows
• Linux
• Android
• IOS

Hardware Requirements (graphics card, VR Device, ...)

[BengtGustafsson]

I investigated further and there is nothing in the Collada spec to indicate that reusing a material in more than one polylist would be illegal (see page 5-99 of https://www.khronos.org/files/collada_spec_1_4.pdf). So I do think this is a bug rather than an enhancement, then of course the priorization of this bug is another matter. Note also that it works with colladaloader v1.

[Mugen87]

ColladaLoader2 should support this now (#11502).