I have been experimenting a bit with different workflows to import 3D models in Cesium but I can’t find the best approach yet. I would not mind reading some sort of advanced tutorial on the subject (a bit like https://cesiumjs.org/2014/12/15/glTF-Tips-for-Artists/ but more detailed on the technical aspects)
I am particularly curious to know if the Gltf converter is (or will be) able to handle Collada “Techniques” in order to have out-of-the box specular lighting and/or reflection and bump mappings, etc.
If not directly available from the converter, I would also like to read about the best way to implement custom shaders in Cesium and apply them to some material used by a model: I am not a 3D programmer but could probably work my way around writing my own shaders if given some introductions to it.
Also, among the issues I have with the current converter:
- I see inconsistencies in the results I get from the online converter and the stand alone converter.
- Transparent textures (png) are not well handled by the online converter if only referenced (url set in DAE file): they need to be “dropped” in the online converter along with the DAE file in order to work properly.
- A lot of inconsistencies in the way normals are handled:
- Inverted normals no matter what.
- Smoothing groups sometimes do not work no matter how the model is being processed (3DSmax, Blender, Sketchup, converted to simple mesh, pre-comp normals, etc.)
- Often caused by the use of mirror cloning in 3D editing software (I suspect the vertices order to be responsible here)