Allow biomes to set how rough and high the mapgen gets.

[DragonWrangler1]

Problem

I'm always frustrated when I find mountain biomes that, though they are tall. Aren't rough like they should be. Or plains biomes that are anything but plains. This issue has been reported in Voxelibre as well:

https://git.minetest.land/VoxeLibre/VoxeLibre/issues/2398

Solutions

Add a new biome api feature or a new mapgen to allow for biomes to set the height, and how rough the land is.

The idea would be a 'build it yourself' kind of mapgen, that generates a completely flat world that allows for the biomes to determine the terrain.

Alternatives

Making a lua mapgen to achieve the requested effect.

Additional context

Though the alternative is possible, it wouldn't be extremely stable, or very performant.

[SmallJoker]

1. Start the world
2. Read map_meta.txt as Settings object in Lua
3. Modify mapgen parameters as needed (make sure this only happens while there's no mapblocks generated yet)
4. Save the file
5. Kick the player and demand a rejoin.
6. The world generates as desired.

If you are looking for something else, please be more precise with the request.

[DragonWrangler1]

My request is that biome registries have noise params that allow for each biome to have its own terrain. rather than using height, heat, and humidity to fake it.

Biomes depending on the y level can sometimes lead to unexpected results. A biome that's supposed to be extreme generating as a flat plane.

[kno10]

As biomes are assigned after initial terrain generation, the better approach probably is the opposite: assign a biome to match the terrain. If it is "extreme", then a suitable biome should be assigned.