OldUnreal (Engine)

I know this is a bit off-topic, but just one thing to know: are BSP holes actually possible within a semi-solid brush?

Holes on the semi-solid brush and distorted collisions yes.

What about HOMs? Am I correct that there can't be a HOM on a semi-solid?

You're wrong. Semi-solids can have homs. And they are likely to create some too

Ahh, nothing is completely HOM-safe...

The HOM effect is not due to BSP issues, it's a rendering thing. Simply put, do not overlap two semisolids, ever. This will produce collision errors. I read one of Sweeney's original documentations about the different solidities once, you might want to look it up if you're interested in knowing what to use where (solid vs nonsolid vs semi, different CSGs, ordering..)

Simply put, do not overlap two semisolids, ever.

Darn. That's exactly what did I do. But I didn't get a single error.

Actually, don't overlap anything with a semi-solid.

It is ok if I make a semi-solid, for example, crate and put it ONTO the solid ground?

Actually, don't overlap anything with a semi-solid.

Look at the big boulders in NyLeve, they are going halfway into the ground.

Yeah, it doesn't ALWAYS f*cks everything up, but quite often. And no matter what's the type of brush you're using, not overlapping things is a lot cleaner for your brushwork and for the engine (except brush-sinking, which is a valid technic).

Actually, don't overlap anything with a semi-solid.

I used semisolids to create wires at some my map, no BSP errors. Using solid causes huge room cutoff.

So what makes semisolids, er, semisolid? What DOES semisolid mean anyway?

think Jello.. :p

AFAIK it'd be something like this:

Solid = piece of map's architecture (like, if you add some terrain on flat ground or some metal bars that are never opened/moved) :: Always (de)intersect solids!
Semi-solid = imagine this as a static mesh; something additional, like a crate or a rock)
Nonsolid = simply put, a sheet; if you, however, use a nonsolid cube (like I did in my last DarkMatch map), the result you get is [almost] the same as the result you would get by adding a number of adjacent sheets: acts same as semi-solid, but you can go through it.

Anybody correct me if I'm wrong.