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Constructive Solid Geometry (from now on referred to as CSG) refers to the technique of building up a three dimensional area of space (volume if you want to be more precise) from geometric shapes that either create space or fill space. | Constructive Solid Geometry (from now on referred to as CSG) refers to the technique of building up a three dimensional area of space (volume if you want to be more precise) from geometric shapes that either create space or fill space. | ||
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One of the big differences between making maps for Unreal Tournament and Unreal Tournament 2003 is that far less CSG is used to create its levels. In a UT2003 map, space is hollowed out (and occasionally added) of the solid world using CSG and then populated using [[Legacy:Static Mesh|Static Mesh]]es. See [[Legacy:Building With Static Meshes|Building With Static Meshes]] for more information. | One of the big differences between making maps for Unreal Tournament and Unreal Tournament 2003 is that far less CSG is used to create its levels. In a UT2003 map, space is hollowed out (and occasionally added) of the solid world using CSG and then populated using [[Legacy:Static Mesh|Static Mesh]]es. See [[Legacy:Building With Static Meshes|Building With Static Meshes]] for more information. | ||
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[[Category:Legacy Mapping|{{PAGENAME}}]] | [[Category:Legacy Mapping|{{PAGENAME}}]] |
Revision as of 03:11, 25 May 2003
Contents
Constructive Solid Geometry (CSG)
Constructive Solid Geometry (from now on referred to as CSG) refers to the technique of building up a three dimensional area of space (volume if you want to be more precise) from geometric shapes that either create space or fill space.
A Quick Mind Game
Perhaps the easiest way to think of it is in terms of the addition and subtraction of shapes. Imagine that you have a large solid block of stuff. Imagine that you have a cursor in the shape of a small cube that you can move around in this block of stuff. Using the cursor you can add stuff, or delete (subtract) stuff at the press of a button. If you were to move your cursor into the center of your block and press the subtract button you'd have a hollow cubic space in the middle of your block of stuff.
Still with me?
Now, without moving the cursor, press the add button. Your small cubic space has just vanished. It's been filled with stuff by the addition you just did.
The Reality
CSG works just like the mind game above. Using what is known as a brush (known as the red builder brush in Unreal Editing parlance) shapes are subtracted from and added to (or painted into, keeping with the brush analogy) the solid block of stuff that makes up the Unreal World. It really is just like adding and subtracting numbers with one vitally important difference.
When a shape is subtracted or added to the world it leaves a small wireframe of effect behind to mark its boundaries (this is also confusingly known as a brush). When shapes overlap only the last operation to be performed on the overlapping areas actually has an effect. The order in which operations are performed is important. In Unreal Editing speak this is known as the brush order.
A quick change of pace
When the world is built (called the build process) brushes are processed in the order they were placed within the world, to create a tree of visible surfaces, the BSP Tree. It is this tree of surfaces that you see while playing in an Unreal world.
A Note About UT2003
One of the big differences between making maps for Unreal Tournament and Unreal Tournament 2003 is that far less CSG is used to create its levels. In a UT2003 map, space is hollowed out (and occasionally added) of the solid world using CSG and then populated using Static Meshes. See Building With Static Meshes for more information.