During one of my meditative periods today, I realized how to make a mesh painting tool – an application that loads a mesh and lets you paint directly on it, then creates a texture that will wrap properly onto the mesh. I was also planning on giving an interface so that you could bind Cg-based vertex and fragment programs into the pipeline, which would allow you to paint normal-maps directly onto the object and see it in real-time.
Being only a hobbyist with limited real-world workflow experience, I was wondering if some of you real graphics guys (and/or gals) could give me some pointers on the following issues:
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What is a good object format? I was partway through a trueSpace 3.2 system when I noticed they don’t store normals, which makes it difficult to get things to look right. I’ve done some exporting from Blender via the Python interface. I will probably go with the Blender/Python exportin for myself, just because its a free tool that I can justify using for a hobby. But since I have to translate to some other format anyway, are there any suggestions?
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I should be able to support per-vertex UV coords and anything glGenTexCoord supports. Are there other texture mapping systems I need to understand?
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I am somewhat naive on the perils of UV mapping. I know that some mappings cause poles and other “discontinuities” (ex: spherical mapping compresses all points along the top edge into a single point at the north pole, cylindrical mapping does a radial mapping of top edge along top surface, etc). I have also seen some stuff suggesting that there are higher-space texture coordinates (UVS or UVST) that help with certain kinds of problems, but I have not yet wrapped my brain around what the problems are. Any kinds of accumulated knowledge would be quite handy.
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Vertex skinning: Do vertex skinned models just supply a UV coord for each vertex, or is it more complicated than that? If more complicated, how should I handle the mapping, given that I probably will not support changing the pose of the character in my app?
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I intend to give the program away, with a “send money if it makes you feel better” note. Purely out of curiosity, how much would a hobby-quality, dubiously supported mesh painter application be worth to you? $0 is a perfectly valid response, even if you would use it
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Pretty much anything else that you think would be worthwhile to warn me about…
Thanks for any feedback.
Mac