How to write model-loading-compatible shaders?

Troubleshooting graphics
1

I wrote shaders but when I load models with them, they turn out solid gray. Are there predefined uniforms (like textures) that should be used?

2

If you post the .frag .vert and the .j3md… + how you are applying the material to the model, you’ll get an answer pretty quick. Kinda hard to guess without seeing the shaders.

3

There is ShaderBlow project with many examples:
http://code.google.com/p/jme-glsl-shaders/

Also, if you want to contribute your shaders, you are welcome!