Solids and Semi-Solids

[Deadmeat]

Hey all, quick question.

Can anyone explain to me the difference between solid and semi-solid brushes, what the advantages/disadvantages are and when they should be used etc..? I've mapped on and off for UT for years but never really found a good explaination. Generally speaking I've pretty much never used Semi-Solids but poking around some other maps (particularly the FoT ones) they've been used quite often.

Cheers

[Feralidragon]

In a simple way:

- Semi-solids don't make BSP cuts, they only receive BSP cuts;
- Semi-solids can't get subtracted;
- Best use of semi-solids: decoration and BSP errors solving
- Semi-solids are faster processed and reduce node count

However:
- Semi-solids can cause big bad BSP errors when bad placed
- Semi-solids can give you HOMs and zone merging when used between different zones

A little tip: don't intersect solid brushes with semi-solid ones.

I am thinking that I forgot something...

[NinjaNali]

of i remember rightly, if there is a semi-solid and a solid . subtract on the same line, the texture of the face of the semisolid will always be rendered.
zones always rely on BSP to work properly, semi-solids aren't technically part of the BSP, so they don't work right if they touch one another.
you cant subtract from a semi-solid (again as it isnt BSP) so make it a solid first, intersect it then make it a semi-solid.

[[did]Madis]

In a simple way:

- Semi-solids don't make BSP cuts, they only receive BSP cuts;
- Semi-solids can't get subtracted;
- Best use of semi-solids: decoration and BSP errors solving
- Semi-solids are faster processed and reduce node count

However:
- Semi-solids can cause big bad BSP errors when bad placed
- Semi-solids can give you HOMs and zone merging when used between different zones

A little tip: don't intersect solid brushes with semi-solid ones.

I am thinking that I forgot something...

In some rare cases, using Semi-solids can even up the node count more than using solids. If you use very detailed brushes in places with compex solid architexture, they might recieve more cuts than they would make when they would be solids - f.e. detailed arcs in high-poly corridors. Another workaround seems to be making these details out of multiple smaller brushes rather than one larger 2d-edited brush, they get less faces, therefore, less cuts.

[shakka]

Im pretty sure semi solids are useful as decorations that cannot be reached during gameplay as they reduce map file size.

[Feralidragon]

Im pretty sure semi solids are useful as decorations that cannot be reached during gameplay as they reduce map file size.

That's an urban myth my friend. It's true that ther are usefull as deco, but I will tell you a little secret: build all your map with the max semis possible (obbeying some rules), and your will have a good map with a good performance. So you can and must use semis wherever possible, and you can touch them. The only bug that can occur even when well placed, is occlusion, but that is solved just by turning that semi into a solid one