"Christopher James Huff" <cja### [at] earthlinknet> wrote in message
news:cja### [at] netplexaussieorg...
>
> I'm not sure what you're thinking of or how you're trying to apply that
> idea. I have built a raytracer that does use the depths of the bounds
> intersections: if the bounds intersection of a shape is further than the
> current best intersection, it doesn't bother to do a full intersection
> test. I haven't tested it to see how much of an improvement there is, if
> there is any at all, because it does require additional work to manage
> the extra information.

My assumption (which afaik is/was wrong) was that the bounding box had a
similiar function to the container for an iso-surface (where I may also have
missed the point), i.e. that you only evaluate the shape for points inside the
container, thus saving calculations on points outside the bounding box.

I hadn't realised (and still don't really understand) that the bounding box for
an object has more to do with the camera's interaction with the shape, rather
than just defining the maximum possible extent of the shape.

In other words, you wouldn't bother to evaluate whether the ray had hit, for
example, a sphere for any point outside the sphere's bounding box.

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