resource: codegen biome list

resource/README.md

@@ -11,13 +11,15 @@ work.
 - `extract.py`: Takes the block type information from `blocks.json` and texture data
   from an unpacked Minecraft JAR, storing the result in `colors.json`
 - `generate.py`: Generates `block_types.rs` from `colors.json`
+- `biomes.py`: Generates `biomes.rs` from biome JSON files of an unpacked
+  Minecraft JAR
 - `sign_textures.py`: Generates all needed sign graphics from Minecraft assets
 
 In addition to these scripts, the JSON processor *jq* is a useful tool to work
 with MinedMap's resource metadata.
 
 
-## How to add support for block IDs of a new Minecraft version
+## How to add support for block IDs and biomes of a new Minecraft version
 
 1. Download the Minecraft version you want to support as well as the previous
    version currently supported by MinedMap. You can use the Minecraft launcher
@@ -69,6 +71,17 @@ with MinedMap's resource metadata.
      cargo fmt --all
      ```
 
+8. Update the source code for new biome data:
+
+     ```sh
+     ./biomes.py data/new ../crates/resource/src/biomes.rs
+     cargo fmt --all
+     ```
+
+    After regenerating, check if only new biomes were added. If entries
+    got removed, biomes may have been renamed or merged, requiring updates
+    to the alias list in `crates/resource/src/legacy_biomes.rs`.
+
 After the update, the new version should be tested with old savegames (both
 before and after migration by the new version) as well as newly generated
 worlds. Use creative mode to add the new block types to your test world.