Alain <kua### [at] videotronca> wrote:
> The bounding don't work correctly when used in a way similar to an 
> intersection.
> The bounded object itself is not bounded correctly, it's as if the 
> bounding object is oriented relative to the camera.
> Next, there is a huge problem with the shadows: Most of the time, the 
> part of the original object OUTSIDE the bounding object still cast 
> shadows, but not always.
> It's mostly appen when using some infinite primitive, like a quadric, 
> but can also appen if the bounded object is a finite primitive or some CSG.

I haven't tested your scene, but I think you have a slight
misunderstanding about what bounding objects do.

A bounding object is *not* the same thing as an intersection with an
"invisible" object. It cannot be used to "cut away" parts of an object
because that's not how it works (nor is it intended for that purpose.)

What happens is that when a ray is tested against the object, it will
first be tested against its bounding object, and if it hits that, then
it will be tested against the actual object. This test doesn't actually
care where the bounding object is. Regardless of where it is, it just
tests to see if the ray its hit, and proceeds with the actual intersection
test only if that was so.

From this it follows that if the bounding object does not actually fully
enclose the actual object, you'll get incorrect rendering (the visible
parts of the object will depend on the orientation of the bounding object
with respect the direction of the rays' origin.)

If you want to actually clip the object with another, use clipped_by,
which has been designed for that exact purpose.

And in fact, given that wanting to both bound and clip with the same
object, there's a handy shortcut, namely "clipped_by { bounded_by }"

-- 
                                                          - Warp

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