Trivial Rejection Clipping
One of the keys to all clipping algorithms is the notion of half-space partitioning.
We've seen this before when we discussed how edge equations partition the image plane into
two regions, one negative the other non-negative.
The same notion extends to 3 dimensions, but partitioning elements are planes rather than lines.
The equation of a plane in 3D is given as:
If we orient this plane so that it passes through our viewing position and our look-at direction is
aligned with the normal. Then we can easily partition objects into three classes, those behind our
viewing frustum, those in front, and those that are partially in both half-spaces. Click on the
image above to see examples of these cases.
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