Advance M8-M11 parity workflows

tools/web/generate-weight-paint-golden.py

@@ -0,0 +1,110 @@
+import json
+import pathlib
+import sys
+
+import bpy
+
+
+def group_weight(vertex, group_index):
+    return next((item.weight for item in vertex.groups if item.group == group_index), 0.0)
+
+
+def set_weight(obj, vertex_index, group_index, value):
+    group = obj.vertex_groups[group_index]
+    if value == 0.0:
+        try:
+            group.remove([vertex_index])
+        except RuntimeError:
+            pass
+    else:
+        group.add([vertex_index], value, "REPLACE")
+
+
+def normalize_vertex(obj, vertex_index):
+    vertex = obj.data.vertices[vertex_index]
+    total = sum(item.weight for item in vertex.groups)
+    if total > 0.0:
+        for item in list(vertex.groups):
+            set_weight(obj, vertex_index, item.group, item.weight / total)
+
+
+def limit_vertex(obj, vertex_index, limit):
+    vertex = obj.data.vertices[vertex_index]
+    while len(vertex.groups) > limit:
+        remove = min(vertex.groups, key=lambda item: (item.weight, -item.group))
+        obj.vertex_groups[remove.group].remove([vertex_index])
+
+
+def mirror_map(obj, axis, tolerance):
+    result = {}
+    for source in obj.data.vertices:
+        reflected = source.co.copy()
+        reflected[axis] = -reflected[axis]
+        candidate = min(obj.data.vertices, key=lambda item: ((item.co - reflected).length, item.index))
+        if (candidate.co - reflected).length > tolerance:
+            raise RuntimeError("mesh is not mirror symmetric")
+        result[source.index] = candidate.index
+    if any(result[result[index]] != index for index in result):
+        raise RuntimeError("mesh mirror map is not reciprocal")
+    return result
+
+
+def snapshot(obj):
+    groups = [group.name for group in obj.vertex_groups]
+    return {
+        "groups": groups,
+        "vertices": [
+            {"index": vertex.index, "weights": {
+                groups[item.group]: round(item.weight, 9) for item in vertex.groups
+            }}
+            for vertex in obj.data.vertices
+        ],
+    }
+
+
+def main(blend_path, output_path):
+    bpy.ops.wm.open_mainfile(filepath=str(pathlib.Path(blend_path).resolve()), load_ui=False)
+    obj = bpy.data.objects.get("RiggedShapeObject")
+    if obj is None or obj.type != "MESH":
+        raise RuntimeError("weight paint fixture object is missing")
+    group = obj.vertex_groups.get("WebPaintGroup") or obj.vertex_groups.new(name="WebPaintGroup")
+
+    set_weight(obj, 0, group.index, 0.75)
+    set_weight(obj, 1, group.index, 0.25)
+    steps = [{"name": "initial", **snapshot(obj)}]
+
+    set_weight(obj, 2, group.index, 0.5)
+    normalize_vertex(obj, 2)
+    steps.append({"name": "normalize", **snapshot(obj)})
+
+    set_weight(obj, 3, group.index, 0.4)
+    limit_vertex(obj, 3, 2)
+    normalize_vertex(obj, 3)
+    steps.append({"name": "limit-normalize", **snapshot(obj)})
+
+    mapping = mirror_map(obj, 0, 1e-4)
+    for source in (0, mapping[0]):
+        set_weight(obj, source, group.index, 0.9)
+    steps.append({"name": "mirror", **snapshot(obj)})
+
+    result = {
+        "schemaVersion": 1,
+        "fixture": pathlib.Path(blend_path).name,
+        "blenderVersion": bpy.app.version_string,
+        "object": obj.name,
+        "mesh": obj.data.name,
+        "operations": [
+            {"name": "normalize", "vertex": 2},
+            {"name": "limit-normalize", "vertex": 3, "limit": 2},
+            {"name": "mirror", "vertices": [0, 1], "axis": 0, "tolerance": 1e-4},
+        ],
+        "steps": steps,
+        "tolerance": 1e-6,
+    }
+    pathlib.Path(output_path).write_text(json.dumps(result, indent=2, sort_keys=True) + "\n", encoding="utf-8")
+
+
+if __name__ == "__main__":
+    if "--" not in sys.argv or len(sys.argv) <= sys.argv.index("--") + 2:
+        raise SystemExit("usage: blender -b --python generate-weight-paint-golden.py -- input.blend output.json")
+    main(*sys.argv[sys.argv.index("--") + 1:sys.argv.index("--") + 3])