How to modify a vanilla biome characteristics?

[gabrieldi]

Hi! I want to to change some Desert biome properties, like it's size, to have some structure generated in it and some mobs too, is that possible? If so, how do I do that? Would be thankful with tutorials too. 

[JaredBGreat]

OK, there is more than one way to do most of these things.

 

To add structure you could:

• You could create a generation handler that implements IWorldGenerator and is registered with forge.  This is most often used to place things like ores or flowers, but can be used to place anything (I use it for Doomlike Dungeons).  You would just have to have your code test for the desert biome when deciding to place the structure.  You don't need to change the biome at all to do this.
   
• You could create it as a biome feature, which the biome decorator can sometimes add (this if often used for trees, cacti, pools, etc.).  Here is an example: https://github.com/BlackJar72/ClimaticBiomePlacement/blob/master/main/java/jaredbgreat/climaticbiome/generation/feature/GenPine.java  -- vanilla example can be found in the world generation packages (under world).  I'm pretty sure you would need to create a modded biome (even if just extending a vanilla one) to do it that way.
   
• The feature could be created in many ways -- procedurally, from an array, or from the files now stored as structure under assets (I don't know how to use those, since I mostly interested in procedural generation).

To add mobs just use EntityRegistry.addSpawn() like diesieben07 said.  Again, you don't need a new or modded biome to do this.  So up to this point, you don't really need to mod the biome itself.

 

To change things like size you'd have to get deep into the biome provider and/or gen layers -- I've created a biome provider, but it bypasses the noise layers / gen layers, so I don't know much about those.  This is some of the most technical code in the game, and a lot of it is very mathy, so not to be done lightly, and might not be worth it just to make some changes to one biome.

 

You could probably change where they're found be registering them in other biome groups, though, and it is possible to extend a biome to make a new one with new features and register it.  I have no idea if you can remove biomes from the biome groups to keep the vanilla from appearing.  You'd have to figure that out yourself.

Edited January 12, 2018 by JaredBGreat