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Archive Notice: This thread is old and no longer active. It is here for reference purposes. This thread was created on an older version of the flipcode forums, before the site closed in 2005. Please keep that in mind as you view this thread, as many of the topics and opinions may be outdated.

July 05, 1999, 04:54 PM

Hello all!

I have i couple of questions and I since I'm just a beginner I am not very familiar with visibility determination.

Does anybody know which visibility determination methods are used in common racing games?
In general, what is the most popular visibility system for outdoor environments? And why?
For indoor environments? And I would really like to know which visibility system space games are using.

Thanks in advance,

P.S. sorry for any mistakes you may find in my posting, I'm not a native speaker of english.

Jaap Suter

July 06, 1999, 06:13 AM

My guess would be:

race games: clip against frustrum only
outdoor: quadtree in combination with frustrum clipping
indoor: you tell me!!! :) (portals, bsp-tree, octrees+something, z-buffer) Everything! :)
space games: octree + clipping against frustrum

(mmm, i guess this is not a very detailed answer. I'm sorry)


Chris Babcock

July 06, 1999, 11:20 PM

>>Does anybody know which visibility determination methods are used in common racing games?

Racing games are a particularly nice class of 3d application; you're usually stuck on a nice track. This means you can break up the track into sections and precompute visibility for each of these track sections and just store it with that section. When you go to render, you find out which section the camera (car) is in and just render the polygons listed. Nice and easy. Racing games also let you do fun stuff like use only the visible shells of buildings, etc since you can't see the back surfaces or in some cases certain sides.

If you're doing a non-track based racing game things get a bit more tricky. Octree or quadtree (since car is always on ground, 2d approx is usually good enough) datastructures start to look more attractive. You can either just use them to help speed up view volume culling of objects, or store visibility information in the nodes like you did with track sections. Which you'll want to use will depend on the size of the playing field and overdraw concerns.

Chris Babcock

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