Phased Generation

Phased generation is a process wherein world generation is separated into specialized phases, each only doing 'one thing', caching the result, and feeding into the next phase, on and on until some final 'completed' phase is reached.

This can happen both globally, when a world is initially created, and locally as sections of the world need to be realized into actual voxel volumes for simulation/play.

For example, phased generation can roughly look like this:

1. Generate base terrain: only the 'ground', 'fluid' and 'air'.
2. Generate structures that may change the terrain on a large scale, such as rivers, paths, craters, megaflora, cities, etc.
3. Derive terrain slopes/gradients and sky visibility/occlusion.
4. Generate the surface layers (i.e.: grass/soil) of the terrain.
5. Generate structures that don't change the terrain (but affect large foliage), such as ruins and city buildings.
6. Generate large scale decoration (trees and boulders).
7. Generate small scale decoration (bushes, flowers, rocks).
8. Build acceleration structures and initial lighting.

Each of these phases requires less and less scale, and thus active volume, to take into account.

References

• https://minecraft.wiki/w/World_generation