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yodaman

what method of culling probably???

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Im curious what techniques a game such as the following uses for culling, since theres small misc geometry scattered about the terrain. I figured probably octrees. hmm. Edit: let me refrase my question, would it be feasible to use an octree instead of a bsp? Also, im working on a small rpg with some friends. The world will use a 3d terrain and the characters, 2d. Anyway, the view will be limited so I was thinking I could use scissor testing for clipping. What that be a bad idea? (overhead style sorta zelda). Thanks. edit: I got that image from this site.

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Well, I can't tell what culling system they're using by just looking at the images. For all I know, it might just be brute force. But to be realistic, I think an octree system would work nicely, if implemented properly. It seems that most of the stuff in the scenes is static anyway...

As for octree vs. bsp, well, this has been discussed so many times on this board. So, I'm going to direct you to the very helpful search function. But if you want my opinion, I'd place my bet on octrees.

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Guest Anonymous Poster
Usually, an octree is used for outdoor environments and a BSP tree for indoor ones.

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Guest Anonymous Poster
Like the above poster said there is no way to know.

But I would personally use...

Top and middle: Quad-tree with occluders
Bottom: BSP, or possibly Oct-tree

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Quote:
Original post by Anonymous Poster
Usually, an octree is used for outdoor environments and a BSP tree for indoor ones.

Dammit, this post was mine. I forgot to put the password...

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Since those are from the Torque Game Engine (Hi Test Guy!)... it uses a quad-tree for exterior and BSP for interiors.

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Quote:
Original post by Anonymous Poster
Usually, an octree is used for outdoor environments and a BSP tree for indoor ones.


octree + outdoors? i somehow dislike this solution

since
a) quadtrees perform much better with outdoor environments
b) octrees should be used for leveled outdoor environments or maybe just for culling complex PVSs potential visible sets

i d do it a little bit different

1. use a quadtree
2. add convex hulls for indoor culling, can be done easily with brush based editors
use the faces of these convex hulls that touch those of other convex hulls as some kind of portal and link these portals into a quadtree

and give every quadtree a min max boundary of the geometry it gets assigned

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octree + outdoors? i somehow dislike this solution


Octrees work quite well in highly culled outdoor enviroments. Especially when you factor in a highly used occlusion algorithm. Mainly with scenes which (as you said) are multi layered. The main difference is the extent of the Y direction required for validating the octree reference.

i suggest some other versions:
1) Loose octrees
2) ABT's

I'm a personal fan of ABT's & Occlusion Culling, and have sworn off any PVS/Portal system of any kind. These methods are really becoming a thing of the past.

~Main

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Quote:
Original post by duhroach
Quote:

octree + outdoors? i somehow dislike this solution


Octrees work quite well in highly culled outdoor enviroments. Especially when you factor in a highly used occlusion algorithm. Mainly with scenes which (as you said) are multi layered. The main difference is the extent of the Y direction required for validating the octree reference.

i suggest some other versions:
1) Loose octrees
2) ABT's

I'm a personal fan of ABT's & Occlusion Culling, and have sworn off any PVS/Portal system of any kind. These methods are really becoming a thing of the past.

~Main



well you are wrong with the PVS thing

in my engine you can place convex hulls, whose content is represented as a PVS ingame, this allows me to effectivly cull away everything that can not be seen from the players point of view

lets say you are working on a ww2 game and want to create a map like stalingrad, you could either use a octree quadtree culling method where you have a lot of overdraw or you use a manual PVS implementation where you cull away entire parts of a city

imagine bombed out roads with complex indoor structures, it would be hard to cull these without a PVS implementation



as to octrees,you could use them for some kind of space simulation if you want to

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Quote:
Original post by Basiror
imagine bombed out roads with complex indoor structures, it would be hard to cull these without a PVS implementation


Not really, as you'd using some form of occlusion culling ( a HOM for instance ).

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