diff --git a/assets/_sources/_gen.js b/assets/_sources/_gen.js
new file mode 100644
index 0000000..6768a36
--- /dev/null
+++ b/assets/_sources/_gen.js
@@ -0,0 +1,21 @@
+const { PNG } = require('pngjs');
+const fs = require('node:fs');
+const path = require('node:path');
+
+function writeSolidRGBA(p, w, h, rgba) {
+    const png = new PNG({ width: w, height: h });
+    for (let i = 0; i < png.data.length; i += 4) {
+        png.data[i + 0] = rgba[0];
+        png.data[i + 1] = rgba[1];
+        png.data[i + 2] = rgba[2];
+        png.data[i + 3] = rgba[3];
+    }
+    fs.writeFileSync(p, PNG.sync.write(png));
+}
+
+const SOURCES = path.resolve(__dirname);
+writeSolidRGBA(path.join(SOURCES, 'demo_tilemap',  'grass_diffuse.png'), 32, 32, [110, 170,  80, 255]);
+writeSolidRGBA(path.join(SOURCES, 'demo_tilemap',  'stone_diffuse.png'), 32, 32, [120, 120, 120, 255]);
+writeSolidRGBA(path.join(SOURCES, 'walls_tilemap', 'wall_brick_diffuse.png'), 32, 32, [180, 100,  80, 255]);
+writeSolidRGBA(path.join(SOURCES, 'walls_tilemap', 'wall_wood_diffuse.png'),  32, 32, [140,  90,  50, 255]);
+console.log('test-stub sources generated');
diff --git a/assets/_sources/demo_tilemap/grass_diffuse.png b/assets/_sources/demo_tilemap/grass_diffuse.png
new file mode 100644
index 0000000..da75774
Binary files /dev/null and b/assets/_sources/demo_tilemap/grass_diffuse.png differ
diff --git a/assets/_sources/demo_tilemap/stone_diffuse.png b/assets/_sources/demo_tilemap/stone_diffuse.png
new file mode 100644
index 0000000..7991b4c
Binary files /dev/null and b/assets/_sources/demo_tilemap/stone_diffuse.png differ
diff --git a/assets/_sources/walls_tilemap/wall_brick_diffuse.png b/assets/_sources/walls_tilemap/wall_brick_diffuse.png
new file mode 100644
index 0000000..7811e7c
Binary files /dev/null and b/assets/_sources/walls_tilemap/wall_brick_diffuse.png differ
diff --git a/assets/_sources/walls_tilemap/wall_wood_diffuse.png b/assets/_sources/walls_tilemap/wall_wood_diffuse.png
new file mode 100644
index 0000000..69085d1
Binary files /dev/null and b/assets/_sources/walls_tilemap/wall_wood_diffuse.png differ
diff --git a/assets/atlases/demo_tilemap/tiles.atlas.json b/assets/atlases/demo_tilemap/tiles.atlas.json
new file mode 100644
index 0000000..35688da
--- /dev/null
+++ b/assets/atlases/demo_tilemap/tiles.atlas.json
@@ -0,0 +1,31 @@
+{
+  "atlas_id": "demo_tilemap",
+  "atlas_version": 1,
+  "atlas_size_px": [
+    64,
+    64
+  ],
+  "tile_size_px": 32,
+  "tiles": [
+    {
+      "id": 1,
+      "name": "grass",
+      "uv": [
+        0,
+        0,
+        32,
+        32
+      ]
+    },
+    {
+      "id": 2,
+      "name": "stone",
+      "uv": [
+        32,
+        0,
+        32,
+        32
+      ]
+    }
+  ]
+}
diff --git a/assets/atlases/demo_tilemap/tiles.atlas.lock.json b/assets/atlases/demo_tilemap/tiles.atlas.lock.json
new file mode 100644
index 0000000..b06ca88
--- /dev/null
+++ b/assets/atlases/demo_tilemap/tiles.atlas.lock.json
@@ -0,0 +1,9 @@
+{
+  "atlas_id": "demo_tilemap",
+  "bindings": {
+    "grass": 1,
+    "stone": 2
+  },
+  "deleted": [],
+  "next_id": 3
+}
diff --git a/assets/atlases/demo_tilemap/tiles.diffuse.atlas.png b/assets/atlases/demo_tilemap/tiles.diffuse.atlas.png
new file mode 100644
index 0000000..82f2d3d
Binary files /dev/null and b/assets/atlases/demo_tilemap/tiles.diffuse.atlas.png differ
diff --git a/assets/atlases/demo_tilemap/tiles.height.atlas.png b/assets/atlases/demo_tilemap/tiles.height.atlas.png
new file mode 100644
index 0000000..a5d5cf1
Binary files /dev/null and b/assets/atlases/demo_tilemap/tiles.height.atlas.png differ
diff --git a/assets/atlases/walls_tilemap/tiles.atlas.json b/assets/atlases/walls_tilemap/tiles.atlas.json
new file mode 100644
index 0000000..f7fe07a
--- /dev/null
+++ b/assets/atlases/walls_tilemap/tiles.atlas.json
@@ -0,0 +1,33 @@
+{
+  "atlas_id": "walls_tilemap",
+  "atlas_version": 1,
+  "atlas_size_px": [
+    64,
+    64
+  ],
+  "tile_size_px": 32,
+  "tiles": [
+    {
+      "id": 1,
+      "name": "wall_brick",
+      "uv": [
+        0,
+        0,
+        32,
+        32
+      ],
+      "blocks_sight": true
+    },
+    {
+      "id": 2,
+      "name": "wall_wood",
+      "uv": [
+        32,
+        0,
+        32,
+        32
+      ],
+      "blocks_sight": true
+    }
+  ]
+}
diff --git a/assets/atlases/walls_tilemap/tiles.atlas.lock.json b/assets/atlases/walls_tilemap/tiles.atlas.lock.json
new file mode 100644
index 0000000..8082971
--- /dev/null
+++ b/assets/atlases/walls_tilemap/tiles.atlas.lock.json
@@ -0,0 +1,9 @@
+{
+  "atlas_id": "walls_tilemap",
+  "bindings": {
+    "wall_brick": 1,
+    "wall_wood": 2
+  },
+  "deleted": [],
+  "next_id": 3
+}
diff --git a/assets/atlases/walls_tilemap/tiles.diffuse.atlas.png b/assets/atlases/walls_tilemap/tiles.diffuse.atlas.png
new file mode 100644
index 0000000..dbf9572
Binary files /dev/null and b/assets/atlases/walls_tilemap/tiles.diffuse.atlas.png differ
diff --git a/assets/atlases/walls_tilemap/tiles.height.atlas.png b/assets/atlases/walls_tilemap/tiles.height.atlas.png
new file mode 100644
index 0000000..a5d5cf1
Binary files /dev/null and b/assets/atlases/walls_tilemap/tiles.height.atlas.png differ
diff --git a/assets/tiles/demo_tilemap.tilemap.json b/assets/tiles/demo_tilemap.tilemap.json
deleted file mode 100644
index a5381d2..0000000
--- a/assets/tiles/demo_tilemap.tilemap.json
+++ /dev/null
@@ -1,8 +0,0 @@
-{
-  "id": "demo_tilemap",
-  "tile_size": 32,
-  "tiles": [
-    {"id": "grass", "walkable": true,  "color": [110, 170, 80]},
-    {"id": "stone", "walkable": false, "color": [120, 120, 120]}
-  ]
-}
diff --git a/assets/tiles/walls_tilemap.tilemap.json b/assets/tiles/walls_tilemap.tilemap.json
deleted file mode 100644
index 3db2075..0000000
--- a/assets/tiles/walls_tilemap.tilemap.json
+++ /dev/null
@@ -1,8 +0,0 @@
-{
-  "id": "walls_tilemap",
-  "tile_size": 32,
-  "tiles": [
-    {"id": "wall_brick", "walkable": false, "color": [180, 100, 80]},
-    {"id": "wall_wood",  "walkable": false, "color": [140, 90, 50]}
-  ]
-}
diff --git a/scripts/bake.sh b/scripts/bake.sh
new file mode 100644
index 0000000..23a79da
--- /dev/null
+++ b/scripts/bake.sh
@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+# Re-bake the stub atlases used by maps-test fixtures.
+set -euo pipefail
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+LIB_DIR="$(cd "$SCRIPT_DIR/.." && pwd)"
+BAKER=~/Projects/Sporel/sporel-tool-atlas-baker/bin/atlas-baker.js
+
+node "$BAKER" \
+    --in  "$LIB_DIR/assets/_sources/demo_tilemap" \
+    --out "$LIB_DIR/assets/atlases/demo_tilemap" \
+    --atlas-id demo_tilemap \
+    --tile-size 32
+
+node "$BAKER" \
+    --in  "$LIB_DIR/assets/_sources/walls_tilemap" \
+    --out "$LIB_DIR/assets/atlases/walls_tilemap" \
+    --atlas-id walls_tilemap \
+    --tile-size 32 \
+    --blocks-sight-pattern '^wall_'