statis mesh's in maps vs. brush's

[f-c-m]

There are obviously differences between BSP brush geometry and
imported static mesh geometry when used in maps.

I dont have much advanced knowledge of mapping for HL1 or HL2(obviously).

I Have made a basic TFC "hunted" map back within 6 months of TFC's 1st release.. so its pretty dated knowledge and I never imported any static mesh's.. (I dont even think you could back in that old ver. of worldcraft.. but i dunno)..

anyways.. back on point..

Can anyone here list the standard differences between making geometry with brush's rather then static meshes?..

Performance? physics? uses?. mobility? .. anything anyone knows about the differences between the two.. throw some info in this thread.. I think it will help myself and others determine which geometry to use for what purposes..

for example. I seem to remember someone mentioning Bullets pass right through static mesh's.. but are blocked by brush geometry?.. is this the case?

-B

 

[derby]

First off, brushes are nothing to do with BSPs.

Originally posted by derby

BSP stands for binary space partition. That is each polygon is stored in a large binary tree where the left subtree contains all the polygons on one side of a diving plane and the right children contins polygons on the other side. BSP trees are used to gain the correct drawing order of world polygons.

A BSP tree is the major constuant of a HL2 map, even if you were to have everything in the map modelled as meshes there would still have to be a BSP tree. Note that the BSP tree is only part of the .bsp file the rest of it contains entity lists, light data vis data etc.

Originally posted by derby

Half-life1 & 2 maps are made of convex objects called brushes. Each brush is defined by the solid region bounded by four or more infinite planes.

So you can think of a brush as a solid object. All the world brushes get converted into one mesh when the BSP tree is generated.

Originally posted by derby

The reason .map files use the plane based definition is to simplify the process of creating the BSP tree, as there are simple ways to test for the intersection of two planes etc.

Now that we have the terminology & background sorted, I'll answer your question.

Half-life2 is designed so that large simple objects such as buildings roads etc. are made from brushes. The level detail for these objects is fixed, they take the same ammount of time to draw no matter how far you are away. They must be kept simple because if you are far away from them they still need to be drawn, but there may be many other things in the field of view.

Static meshes are used for props, objects etc. these can have several levels of detail, so if you are far away from them low poly versions are substituted for speed.

I'm not sure at this stage wether static meshes block visibility. In HL1, if you had a solid opaque wall between you and the rest of the map, only the wall was drawn, the rest can be skipped as you can't see it. If you stood between a staic mesh of a wall, the rest of the level would stillbe drawn behind it as the game doesn't know you can't see past the wall. I suspect that this will still be the case in HL2 as it uses similar VIS algorithms as HL1.

So use brushes for anything big, like a house, to ensure the engine doesn't draw anything behind the house and use meshes for details and objects that you can scale with distance.

Static meshes and brushes seem to behave in the same way as far as physics is concerned. Wether or not bullets pass through them has nothing to do with wether objects are brush based or mesh based, it depends on the physics engine being used.

 

[f-c-m]

Definately good response

Thats an excellent response,
I already know all about visgroups and the drawing behind the brush wall... wondered about the static mesh & its drawing behind it ..

and definately know all about LOD and look forward to messhin with this with some of my models.

Now here's a question.. how do you import a mesh from 3dsmax into worldcraft?...
Do I need to convert it to a MDL file?
or export as DXF?...

Im confused in the conversion process..
is there a 3dsmax plugin for it?..

 

[IchI]

meshs are normally made from triangles and are made in exsternal programs. Other things like geometry and made of any sided shapes. I think.

Summat like that.

 

[Papau]

Everything becomes triangles in BSP; brushes, meshes, it doesn't matter. Bullets, players, whatever, passing through surfaces are a function of the surface properties of the textures used as defined in the shader. Doesn't matter if it's on a brush or mesh. Models cull. Static meshes cull if you want them to; again dictated by shader properties. Static meshes are supported by most editors (UT2x, Quark, Radiant).