I wrote a parallax occlusion Shader in Rendermonkey. Unfortunately due to the fact that the devartives in flow control elements are undefined, the ARB_texture_lod extension would be neccesarry for this shader in glsl with shadermodel 3.0. Until this extension is released EXT_gpu_shader4 has to be used as replacement. So this shader only runs on gForce 8+ cards. Ati doesn’t support that extension yet.