View Full Version : Question: Sealed World Rules

07 July 2005, 08:52 PM
Hey guys, I have a question:
How important is it in todays engines that us modellers follow the sealed world rules (will explain what they are in a bit) for example say I were modelling a car, that car would be a 100% sealed volume, the model would have no 'open faces' or 'holes', whatever you wish to call it?
Also (and related), can meshes intersect through each other, or is it preferred that its all joined up properly?

I have always kept my models to the sealed world rules and nothing intersecting, but i don't know how important this is with engines like source and unreal, just wondering.

if need be i will post some pics showing what i mean.

07 July 2005, 09:03 PM
Its always good practice to have clean meshes and no intersecting, however whether it will cause a problem or not is pretty much engine specific. I have worked in both Unreal and Source and havenít had any problems with intersecting brushes.

07 July 2005, 09:16 PM
I think intersecting meshes are basically just fine now, I have even been instructed to use them MORE often. This is thanks to the new ubiquitous z-buffer that almost entirely eliminates z-fighting (see any PS1 game for a great example of that).

However, there are a couple of cases when it is still definitely bad to not have a sealed mesh:

1 - BSP hull for basically any FPS game engine. These need to be sealed or else the algorithms that generate the binary space partition tree and other useful graphs (collision hull, etc) will fail miserably.

2 - Many game engines now need closed meshes in order to properly generate shadows. I know this is the case in DooM3 and the new Microsoft Flight Simulator engine. Not sure about Unreal?

07 July 2005, 09:55 PM
ah ok, thanks :)
There are some frustrating moments when modelling when i am trying to get everything perfect, i guess i can relax a bit now:P

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07 July 2005, 09:55 PM
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