New progress

Result of trial and error. By accident, we generate some cool images.

pop-artBoxy
Paint-Effect
Charcoal
after 3-way blending, with only one intensity level

Current Problem:

1. Cannot set up geometry shader, missing support for extensions, "GL_NV_gpu_program4" and "GL_ARB_texture_float", we instead use the multi-texture method suggested by the author. 3-way blending looks fine, the interior lines look kind of continuous.

2. Instead of using 3d-texture (we don't know how to set up in openGL and CG), we are using very large 2d-texture (with different intensity textures all laid out on one 2d-texture). The problem is we couldn't pass a texture with size larger than 1000 x 1000 into the program.

Future work:

Incorporate light intensity difference into the texture mapping. Give the model more 3-dimensional look. Create more pencil textures and move the preprocessing part out. Give user mouse control.