Update worldgen exporter features

README.md

@@ -0,0 +1,101 @@
+MC Worldgen
+===========
+
+Procedural Minecraft Java region exporter. The C exporter is the maintained path:
+it builds without Python dependencies and writes `.mca` region files that can be
+copied into an existing world's `region/` folder.
+
+Requirements
+------------
+
+- GCC or Clang
+- `make`
+- zlib development headers (`zlib1g-dev` on Debian/Ubuntu)
+- pthreads, normally included with libc toolchains
+
+Build
+-----
+
+```sh
+cd worldgen-c
+make
+```
+
+Quick smoke test:
+
+```sh
+./bin/worldgen --radius 0 --out /tmp/mcworldgen-smoke
+```
+
+That should create `/tmp/mcworldgen-smoke/r.0.0.mca`.
+
+Diagnostic feature scan:
+
+```sh
+make scan
+./bin/worldgen-scan --radius 2 --center-x -3200 --center-z 3200
+```
+
+The scanner prints counts for cabin blocks, gravel/path columns, redwood biome
+columns, and titan-height tree trunks.
+
+Generate Regions
+----------------
+
+Small area around chunk 0,0:
+
+```sh
+./bin/worldgen --radius 4 --trails --out output
+```
+
+Specific chunk rectangle:
+
+```sh
+./bin/worldgen --min-x -8 --max-x 8 --min-z -8 --max-z 8 --trails --out output
+```
+
+Useful options:
+
+- `--radius N`: generate chunks from `center - N` through `center + N`.
+- `--center-x X --center-z Z`: center chunk for radius mode.
+- `--min-x --max-x --min-z --max-z`: explicit chunk bounds.
+- `--threads N`: worker thread count.
+- `--seed S`: deterministic world seed.
+- `--sea-level L`: sea level, default `70`.
+- `--snow-line H`: snow threshold, default `sea-level + 38`.
+- `--trails`: enable trail and cabin prepass.
+- `--format mca|bin`: write Minecraft region files or raw debug chunks.
+- `--out DIR`: output directory.
+
+Features
+--------
+
+- Redwoods are enabled automatically. The biome classifier marks high-rainfall,
+  higher-relief areas as redwood forest, then places titan trees, dirt/mulch
+  floor cover, tall grass, and occasional fallen logs.
+- Cabins are enabled automatically. With `--trails`, cabins only try to spawn on
+  chunks crossed by the trail network so their spur paths can connect to roads.
+  Without `--trails`, cabins can still spawn, but they are rarer and unconnected.
+- Trails are optional because they need a prepass over the target area. Use
+  `--trails` when you want roads and better-connected cabins.
+
+Minecraft Version
+-----------------
+
+The exporter writes Java Edition 1.17.1 chunk data (`DataVersion` 2730). That
+version is chosen because the generator includes copper ore. Open the generated
+regions in Minecraft Java 1.17.1 or a newer version that can upgrade old worlds.
+
+The exporter writes region files only. To use them in game, create or choose a
+Java world, close Minecraft, back up the save, and replace or add files under:
+
+```text
+<minecraft save>/region/
+```
+
+Python Exporter
+---------------
+
+`export_mca.py` is the older prototype exporter. It now shares the same 1.17.1
+data version and maps generated coal correctly, but the C exporter is faster and
+has the current terrain features.