   Camera Position in Model(Object) Space
  In OpenGL, with in a shader.  What's the easiest way to get the view vector in model space?I would think that multiplying the ModelView matrix with the Vertex position would give me this.  mul(modelView, vtx_pos).  Is my math wrong?  If so, what is wrong with it?  This doesn't seem to be working for me.Any other quick methods?  I have this working where I give the shader the a camera position in world space and then calculate the modelspace position using the inverse world matrix, but I want to try and avoid this.   
  Anyone?   ;  Hmmm, inless I'm going crazy what you've got should work... you might want to normalise the result however so its a vector.There isn't any point in passing the camera position in to the shader as the camera stays at (0,0,0) and the rest of the world moves around it, thus transforming the vertex's position by the MV matrix gives you a position in camera space, which is a direction vector from (0,0,0), normalising should sort out any maths issues.   