   Projective Texture Coords
  Is there a way, to calculate an XY position from a 4 element vector? The problem i''m having is that I have calculated a 4D texture projection coordinate, which works in nVidia texture shaders. But opengl ARB fragment shaders can only use 1D/2D/3D texture coordinates, and so my Shader breaks. So what I need is a way to modify the x and y texture coordinate values so that they are equivalent to the result produced by the 4D vector. I can''t seem to get my head around this one.   One by one, the peguins steal my sanity. 