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Warp wrote:
> John VanSickle <evi### [at] hotmail com> wrote:
>> the ray-tracing algorithm requires that all of the scene geometry exist
>> in memory all at once.
>
> I don't think that's true. You can have bounding boxes for objects loaded
> into memory instead of the objects themselves, and test against those boxes.
> Only if the box is hit you load the object itself into memory and test the
> ray against it. This process can be cached so that least used objects can
> be dropped from memory.
They used a combination of this with procedural geometry in Monsters,
Inc, I believe. If I understand their comments correctly, then each of
the children's doors was basically a single flat polygon and a random
seed. If that door needed to be drawn (rays striking it or something),
then the geometry and texturing for that door would be generated from
the seed, used, and then discarded when not needed anymore. It was the
only way they could keep millions of doors in memory at once.
> Other optimizations can be used as well: For example, if an object is
> far enough (looks very small from the point of view of the origin of the
> current ray being traced), a billboard graphic can be used instead of the
> object itself. (Or, in some cases, the object could be ignored completely.)
Progressive LOD - coming soon to a theatre near you! ;)
--
...Ben Chambers
www.pacificwebguy.com
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