frustum & box - intersection volume

You could calculate the effective radius for the bounding box and then use that to determine if the box is wihtinn or outside the view frustum.

Ok, so you have a box. First you get the vectors X, Y and Z which is "Width, Height and Thickness". Then you need the Normal of the view frustum plane you want to test against, call it N. The formula would look like this:

Reff = (|X.N|+|Y.N|+|Z.N|) / 2

Then you test against your plane P, and the center of the box Q. Calculate the radius for every plane and if for any plane P.Q <= -Reff then the box is outside. (hope i got it right)


I got this from the book Mathematics for 3D game programming & computer games ISBN:1-58450-277-0 which is a book i can really recommend. =)