World and levels › Terrain
Caves, arches and overhangs: when a heightmap isn’t enough
Know first: Landscape: terrain from a heightmap
This lesson is about the shapes a heightmap can’t make: caves, arches, overhanging cliffs and tunnels. You’ll see why the usual game terrain can’t hold them, and four ways to add them anyway. The four are rock meshes on top of the ground, a hole in the ground with a cave behind it, voxels, and terrain made as one big mesh. For each way, you’ll see how the seam is hidden and what it costs.
Why this matters
A cave mouth, a stone arch or a cliff that leans over a path is the kind of place players remember and use to find their way: a landmark (the lesson on wayfinding). Yet the ground of most open worlds is a heightmap, and a heightmap can’t make any of these shapes. The lesson on landscape shows the limit itself. This lesson is about the ways around it, because each way has its own price in work, memory and drawing time.