Invisible wrote:
> Also, how does it figure out which polygons to draw? It can't possibly 
> draw all 10 million polygons every frame - and yet, figuring out which 
> ones are visible would seem to take more effort than actually drawing 
> them all...

Something similar to bounding volumes (though they're really visibility 
volumes), to limit the areas that are drawn.

For instance, when you're inside a room, the engine knows that it 
doesn't need to draw the rest of the map - it only draws that room. 
Furthermore, it also knows precisely which areas are visible outside the 
window, and which ones aren't.

These volumes are usually computed ahead of time, as a large map can 
take up to several minutes to compute the volumes (depending on the 
game, the level, and the machine being used to build it).

-- 
...Ben Chambers
www.pacificwebguy.com

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