BSP Problem

[Semfry]

There's something I want to do that just doesn't seem to work:



The brush highlighted in yellow is the the start



When I try to subtract a brush in this shape above it I ALWAYS get some infinite surfaces BSP problem. If I use tess cubes there's some strange split in the middle of the leaning surfaces that makes both sides look weird.

I've tried every alternative I can think of, such as making the brushes in the 2D shape editor instead, or remaking the entire room as a five sided cylinder, but nothing works. Should I just give up on that (I'm already doing an alternative anyway), or is there something I'm missing?

[Buff Skeleton]

You are trying to create something that is geometrically impossible: a flat plane that is bent.

If you look closely at the vertices, you only have 4 of them on the left- and right-most faces, but they are arranged in a way that results in the plane getting "bent." You need to have a diagonal connecting two of them so that you have two triangles instead of one bent rectangular plane, which is geometrically impossible to produce (without errors).

Take a sheet of paper, for an example. You can even cut it into the shape you are trying to make, but make sure it has 4 sides. It is flat. Now, try to twist it... without bending the paper. It's impossible: you will always end up forming a crease of some sort down the middle, a diagonal line that splits the rectangular plane into two triangles. In UED, you need to have that diagonal to get this particular shape--i.e., with tess cubes, as you tried. But since it obviously looks strange, you may want to just go with an alternative method.

[Mister_Prophet]

Exactly as Waff said.

I remember the first time I did this and got that error. I thought for a moment that I found a glitch in the matrix. But then I realized my folly.

You can make the subtraction you need for the space you want removed, but you'll have to do it with more than one subtraction. Remove the center block and then make a 3 sided shape with the 2D shaper and use the pyramid tool to get it to stick as far as you need it. Then use that brush to subtract the sides.

[Buff Skeleton]

You can make the subtraction you need for the space you want removed, but you'll have to do it with more than one subtraction. Remove the center block and then make a 3 sided shape with the 2D shaper and use the pyramid tool to get it to stick as far as you need it. Then use that brush to subtract the sides.

Yeah, this is definitely the best way to do it.

[Mister_Prophet]

like so. Or something.

[Taz]

I noticed that BSP problems always seem to appear in underwater areas in my UT maps -- mainly invisible obstacles to movement -- whenever I place ramps or sloping surfaces in those areas. When all the walls in those areas are perfectly vertical and the ceilings and floors perfectly horizontal, then there are no BSP problems. Has anyone experienced the same thing?

[Mister_Prophet]

Your problem sounds like it could either be one of two things:

1. You say that you put architecture into the zone. Does any of it cross the portal (water sheet)? If so, that could be your problem. Sometimes, not all the time, certain brushes have issue when touching sheets. Especially if they are semi-solid or prefabricated. If both, well, I do not want to know what kind of errors you are getting.

2. is the area underwater terrain? I mean, if the sheet is crossing a tessellation or a complex subtraction, that could also be the cause of your problems.

You have a pic?

[Taz]

Afraid I haven't any but I do think you pointed out one thing I tried -- letting a waterzone portal cross a brush at one of its sloping surfaces. I was mainly trying to use negative brushes to create something like a half-submerged passage with a sloping floor, which allows you to walk into and out of the water. Ah, well, guess UnrealEd just doesn't like such things...

[Semfry]

Thanks, my suspicion was something like that, but as I fail at geometry I couldn't be sure.

I'll have to try out that pyramid thing.

[Buff Skeleton]

Afraid I haven't any but I do think you pointed out one thing I tried -- letting a waterzone portal cross a brush at one of its sloping surfaces. I was mainly trying to use negative brushes to create something like a half-submerged passage with a sloping floor, which allows you to walk into and out of the water. Ah, well, guess UnrealEd just doesn't like such things...

I've had water zone portals cross complex terrain geometry without errors before. You just need to make sure that the water sheet is added last, or at least Ordered to Last if you add more geometry that crosses through it. Also, like Proph said, avoid crossing complex brushes or semisolids/nonsolids through the water zone portal, and make SURE water zone sheets stay aligned to the grid.

Do you have any screens of your current setup?

[Taz]

Thanks, Waff. It's not convenient for me to show any screens at present -- maybe next time.

[GTD-Carthage]

Thanks, my suspicion was something like that, but as I fail at geometry I couldn't be sure.

I'll have to try out that pyramid thing.

I have a suggestion too. I don't want to overwrite Proph's method tho:



1 cube brush + vertex editing. The computer I'm posting this on doesn't have UnrealEd so sorry if I can't do a friendlier example.

[TheIronKnuckle]

Wouldn't that shape produce the same errors, it still looks an impossible shape to me.... Unless i'm not seeing it right, those two diamonds on the side should be turned into four triangles. meh

[Hellscrag]

Wouldn't that shape produce the same errors, it still looks an impossible shape to me.... Unless i'm not seeing it right, those two diamonds on the side should be turned into four triangles. meh

If you have two sides on a four-sided surface that are parallel in all three axes then the surface cannot be non-planar ("bent").

[Frieza]

I would go with carthage's shape myself. Unless you just have to extend the wall on the far end upwards.