I am working on a method of reading values from an image map in a fragment shader and using the values as texture coordinates when sampling a texture color with TEX. I need a technical question answered though.
Normally when you call TEX, you use fragment.texcoord[n] followed by 2D to indicate the look-up method. According to the ARB spec fragment.texcoord[n] contains four components s, t, q, and r. What type of values are stored in those components? My hope is that when you do a 2d lookup, q and r are ignored and s and t correspond to U and V on the mesh texture mapping. If this is not the case, I will need to know how I can convert my own U and V values into something that TEX can use where it would normally be given fragment.texcoord[n].