Initial commit: Terrafier v0.1.0

- Core world model (World, Dimension, Tile, Terrain, Platform)
- NBT reader/writer with full tag support
- Anvil region (.mca) format reader with chunk parsing
- Block palette compression and export
- Biome database with Minecraft 1.21 biomes
- CLI commands: new, import, export, info, render
- GUI application with egui (viewport, tools, undo/redo)
- Noise-based heightmap generation and editing operations

License: GPL-3.0-or-later

scripts/extract_colormaps.py

@@ -0,0 +1,90 @@
+"""Download and extract Minecraft colour map PNGs as raw RGB arrays.
+
+The grass.png and foliage.png are 256x256 colour lookup tables.
+x-axis = temperature (0-255), y-axis = downfall (0-255).
+"""
+import urllib.request
+import struct
+import os
+import json
+import zlib
+
+
+def download_file(url):
+    req = urllib.request.Request(url, headers={"User-Agent": "Mozilla/5.0"})
+    resp = urllib.request.urlopen(req, timeout=15)
+    return resp.read()
+
+
+def parse_png_rgb(data):
+    """Parse a PNG file and extract RGB pixel data as a flat array."""
+    # PNG signature check
+    assert data[:8] == b'\x89PNG\r\n\x1a\n', "Not a valid PNG"
+
+    # Find IHDR and IDAT chunks
+    pos = 8
+    chunks = []
+    idat_data = b''
+
+    while pos < len(data):
+        length = struct.unpack('>I', data[pos:pos+4])[0]
+        chunk_type = data[pos+4:pos+8]
+        chunk_data = data[pos+8:pos+8+length]
+
+        if chunk_type == b'IHDR':
+            width = struct.unpack('>I', chunk_data[0:4])[0]
+            height = struct.unpack('>I', chunk_data[4:8])[0]
+            bit_depth = chunk_data[8]
+            color_type = chunk_data[9]
+        elif chunk_type == b'IDAT':
+            idat_data += chunk_data
+        elif chunk_type == b'IEND':
+            break
+
+        pos += 12 + length
+
+    # Decompress
+    raw_data = zlib.decompress(idat_data)
+
+    # Extract RGB pixels (filter byte per row)
+    pixels = []
+    row_size = 1 + width * 3  # filter byte + RGB per pixel
+    for y in range(height):
+        row_start = y * row_size + 1  # skip filter byte
+        for x in range(width):
+            offset = row_start + x * 3
+            r = raw_data[offset]
+            g = raw_data[offset + 1]
+            b = raw_data[offset + 2]
+            pixels.append([r, g, b])
+
+    return width, height, pixels
+
+
+def main():
+    base_url = "https://raw.githubusercontent.com/InventivetalentDev/minecraft-assets/1.21.11/assets/minecraft/textures/colormap"
+    output_dir = os.path.join(os.path.dirname(__file__), "..", "crates", "biome-db", "data")
+
+    for name in ["grass", "foliage"]:
+        url = f"{base_url}/{name}.png"
+        print(f"Downloading {name}.png...")
+        png_data = download_file(url)
+        width, height, pixels = parse_png_rgb(png_data)
+        print(f"  Size: {width}x{height}, pixels: {len(pixels)}")
+
+        # Save as JSON array: [[r,g,b], ...] flattened
+        flat = [v for pixel in pixels for v in pixel]
+        output = {
+            "width": width,
+            "height": height,
+            "data": flat,
+        }
+
+        out_path = os.path.join(output_dir, f"{name}_colormap.json")
+        with open(out_path, "w") as f:
+            json.dump(output, f)
+        print(f"  Written to {out_path}")
+
+
+if __name__ == "__main__":
+    main()