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When doing clipping in homogeneous coordinates, we need to find the coordinates of the intersection of the viewing frustum with the line to be clipped. This can be done easily if we want those coordinates to be in screen space(simply divide by the fourth coordinate). But how can we find those coordinates in 3D space? And do we need to do so in the first place?

Thanks in advance.

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  • $\begingroup$ Dividing by the 4th coordinate would lead to conversion from homogeneous projective coordinates to Carthesian coordinates in Euclidean space. The clipping test then computes intersection with a plane in Euclidean space, with that plane just happening to be axis-aligned. If you need to do the same thing in world-space, the only difference is that the plane is no longer axis-aligned, but ends up being the (not-axis-aligned) planes bounding your viewing frustum. $\endgroup$ – martin_pr Apr 14 at 9:20

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