Terrain (for a city), texturing
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I know how they do it for like grass/dirt and do texture splatting, but for roads and stuff, they have directions and lines, sidewalks as well. Even like if you have a bend in the road.
I'm wondering what the approach is here.
"They" generally use actual separate geometry for each type of object. So the street is a separate mesh from the sidewalk from the grass areas, ect...
From vterrain.org,
Generating 3D Roads
- the idea is to go automatically from a 2D road description to a completely 3D polygonal road
- two main approaches: draped vs. merged
- thin geometry draped on top of the terrain
- pro: simpler and faster, easily changed at runtime, allows the terrain to be a regular grid
- con: "Z-buffer fighting" due to overdraw
- there are ways to reduce the Z-buffer problem
- roads merged into the terrain ("stitched", embedded)
- pro: flawless road boundaries, no overdraw issues
- con: requires computationally complicated and slow preprocessing
- all known commercial programs (see below) prefer this approach
- thin geometry draped on top of the terrain
- with either approach, an algorithm is needed to convert road centerlines
(raw vector data) to a full 2D/3D representation- there are no known published algorithms for doing this!
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