title: How to use 3d texture in opengl and cg shaders?
body: <p>I've got a problem with 3d texture mapping. If I have several 2d textures, and I want to build a 3d texture with these 2d textures. What can I do to put all these data together? The function glTexImage3D ends with a parameter const GLvoid *texels which leads to the data of the texture. But now I have 32 2D textures and want to get a 3D texture. How to do that?</p>
  
  <p>The second question is about image space filtering method. Is there anyone who knows what it is? I should use this method to determine texture coordinate.</p>