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  Hi,Given:-camera location "camera_pos"-modelview matrix "mv_mat"-projection matrix "p_mat"-near clipping plane "n_value"-far clipping plane "f_value"-viewport size "view_size"A depth texture is rendered from the view described.I need to know how to compute, at a texel (i,j) from the depth texture, the world space vector from the original camera position (camera_pos) through that texel.  I have no idea what to do.Thanks,G   
  This may help you:  gluUnproject;  After much deliberation, it is now working!  Thanks!   