The texture mode actually isn't implemented yet. It is implemented in v1.3a, however, and simply allows you to load an image *which is 'projected' onto the loaded model as if there's a slide projector casting the image onto the model from your vantage point, and light pixels in the image translate to creating optics while dark areas are blank. This gives a sort of raw control over how optics are distributed over the surface, instead of relying on how a model's vertices or polygons/edges are situated. I will try to get it all running by the next version ;)