Change of representation: eye in object space

I know it’s very dumb but I cant get around this.
I need to calculate the position of the camera (eye) in object space, given a transformation matrix M.

I think in theory is should be:

eye_obj = col * (V.transpose).inverse * M.inverse

col = {0,0,0,1}
V = 4x4 camera transform matrix retrieved via glGetFloatv(GL_MODELVIEW_MATRIX, V)
M = 4x4 transform matrix defining the center of the object

But clearly this is not working…

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