1 files changed, 39 insertions, 0 deletions
diff --git a/mapgen/viewer_export.py b/mapgen/viewer_export.py
new file mode 100644
index 0000000..e6f51b4
--- /dev/null
+++ b/mapgen/viewer_export.py
@@ -0,0 +1,39 @@
+"""Viewer textures: colourised equirectangular JPEG layers + layers.json."""
+from __future__ import annotations
+
+import json
+from pathlib import Path
+
+import numpy as np
+from PIL import Image
+
+
+def hex_color(c) -> str:
+    return "#%02x%02x%02x" % tuple(int(v) for v in list(c)[:3])
+
+
+def categorical_legend(names, palette) -> dict:
+    return {"type": "categorical",
+            "items": [{"name": n, "color": hex_color(palette[i % len(palette)])} for i, n in enumerate(names)]}
+
+
+def continuous_legend(unit, lo, hi, stops) -> dict:
+    vals = np.linspace(lo, hi, len(stops))
+    return {"type": "continuous", "unit": unit,
+            "stops": [[round(float(v), 4), hex_color(s)] for v, s in zip(vals, stops)]}
+
+
+def write_layer(vdir: Path, L: dict) -> dict:
+    """Write one layer's JPEG; returns its layers.json entry."""
+    vdir.mkdir(parents=True, exist_ok=True)
+    Image.fromarray(np.ascontiguousarray(L["rgb"], dtype=np.uint8)).save(vdir / f"{L['id']}.jpg", quality=90)
+    return {"id": L["id"], "name": L["name"], "file": f"{L['id']}.jpg", "legend": L["legend"]}
+
+
+def write_index(vdir: Path, entries: list[dict]) -> None:
+    vdir.mkdir(parents=True, exist_ok=True)
+    (vdir / "layers.json").write_text(json.dumps(entries, indent=1))
+
+
+def write_all(vdir: Path, layers: list[dict]) -> None:
+    write_index(vdir, [write_layer(vdir, L) for L in layers])