How to draw an environment mapped bump mapped surface in OpenGL on a GeForce class GPU(Not GF3)?
The techdemo from NVidia draws it in two passes. In the first one it draws the Z buffered triangle with an RGB normal map, and renders it to the stencil map too. In the next step it reads back all pixels from the triangle (where it’s indicated by the stencil buffer), and draws them independently with no Z-buffering, calling the glVertex2d command, with texture coordinates set to the color of the correspondant pixel, indicating the normal used in a cube map. Of course cube mapping is enabled during the second step.
This method is correct, but really slow. So please show me something that makes it without drawing independent pixels.