[Suggestion] Mapgen working based on B&W images to gen several worlds

[Mikerhinos]

Hi all,
I was looking for ways to have multiple worlds in 1.
Feature exists in MC, you use portals to go from one world to the other.
I found a topic here a few minutes ago where someone suggested to use size advantage of MT worlds and create worlds at different heights, but it seems pretty long and difficult to regenerate parts of world etc...

So I got an idea, don't know if it's possible, but we could generate "slices" of world with the help of black and white images.
Worlds are a 64k x 64x x 64k blocks cube, so we can make a 64k x 64k pixels white image and paint with black brushes on it.
Then in conf file, say like
"mapgen_slice = 0,image1.png,flat,1,1000"
would tell mapgen to use image1.png as source to generate slice y=0 in world, of 1000 blocks high under that, bottom part being flat, and 1=unbreakable.
We would get a world with a surface to our liking (with flat parts and moutains on others, even seas if you create under y=0, etc...), 1000 blocks under chosen slice, and an unbreakable bottom to avoid players falling in infinite or in other world if we chose to generate another one on a deeper slice.
Between these 1000 blocks, mapgen can do whatever it wants to (adding caves etc...just the normal way it does today).
Basicly it would generate a 1000 blocks (or a different amount) slice and apply a displacement map on top line, and could do that as long as 64k height is not reached.

Maybe it's a stupid idea, maybe my english is so bad that nobody understands lol, anyway I thought of that :)
Problem would be sun and clouds, we'd have to be able to have one per slice if we want to (optional in case of an "underworld" nether style.)

[Krock]

In short like nether (at -20.000m), default map and moon (at 20.000m)?

[Mikerhinos]

For example yes.
With displacement maps it could be very easy to have a precise world surface, for example to do the moon craters map would take seconds to do, or a nether made of canyons etc...
All in same world.