hi all,

I'm a renderman user and not very familiar with GLSL. I try to implement the steep parallax mapping recently according to this poster:
http://graphics.cs.brown.edu/games/SteepParallax/index.html

After go through all the code some questions arise in my mind:
1. In the code the step eye direction on tangent plane need inverse origin eye direction, but it only inverse the x coordinate. why not both x and y coordinate set negative ?
2. Another problem is It says step constant in xy is workable and list code contain some mystery number like 25.6 and 400, what are these number means ?

I appreciate for any help about these issue, thanks in advance