refactor(M03): extract M2 runtime rebuild classifier

src/render/m2/m2_runtime_mesh_rebuild_classifier.gd

@@ -0,0 +1,93 @@
+class_name M2RuntimeMeshRebuildClassifier
+extends RefCounted
+
+## Memoizes whether raw M2 billboard or UV-rotation metadata requires replacing
+## a stale cached runtime mesh. Owns no parser, Mesh, material, Node or RID.
+
+const UV_ROTATION_SPEED_EPSILON := 0.000001
+const MAXIMUM_TEXTURE_STAGES := 4
+
+var _rebuild_required_by_normalized_path: Dictionary = {}
+
+
+## Returns the first memoized rebuild decision for [param normalized_relative_path].
+## [param raw_m2_data] is borrowed and not mutated. The decision remains cached
+## until [method clear], matching the loader map/shutdown reset lifetime.
+func needs_runtime_mesh_rebuild(
+		normalized_relative_path: String,
+		raw_m2_data: Dictionary) -> bool:
+	if _rebuild_required_by_normalized_path.has(normalized_relative_path):
+		return bool(_rebuild_required_by_normalized_path[normalized_relative_path])
+	var rebuild_required := (
+		_raw_data_has_billboards(raw_m2_data)
+		or _raw_data_has_uv_rotation(raw_m2_data)
+	)
+	_rebuild_required_by_normalized_path[normalized_relative_path] = rebuild_required
+	return rebuild_required
+
+
+## Clears every memoized path decision. No Mesh or resource is retained or freed.
+func clear() -> void:
+	_rebuild_required_by_normalized_path.clear()
+
+
+## Returns the number of memoized normalized paths.
+func cached_path_count() -> int:
+	return _rebuild_required_by_normalized_path.size()
+
+
+## Returns a detached normalized-path to boolean decision snapshot.
+func diagnostic_snapshot() -> Dictionary:
+	return _rebuild_required_by_normalized_path.duplicate()
+
+
+func _raw_data_has_billboards(raw_m2_data: Dictionary) -> bool:
+	for batch_variant in raw_m2_data.get("batches", []):
+		if not (batch_variant is Dictionary):
+			continue
+		var batch: Dictionary = batch_variant
+		if (
+				bool(batch.get("has_billboard", false))
+				or int(batch.get("billboard_vertex_count", 0)) > 0
+		):
+			return true
+	return false
+
+
+func _raw_data_has_uv_rotation(raw_m2_data: Dictionary) -> bool:
+	var texture_transforms: Array = raw_m2_data.get("texture_transforms", [])
+	if texture_transforms.is_empty():
+		return false
+	var texture_transform_combos: PackedInt32Array = raw_m2_data.get(
+		"texture_transform_combos",
+		PackedInt32Array()
+	)
+	if texture_transform_combos.is_empty():
+		return false
+	for batch_variant in raw_m2_data.get("batches", []):
+		if not (batch_variant is Dictionary):
+			continue
+		var batch: Dictionary = batch_variant
+		var texture_count := maxi(1, int(batch.get("texture_count", 1)))
+		var base_combo_index := int(batch.get("texture_transform_combo_index", -1))
+		for texture_stage in mini(texture_count, MAXIMUM_TEXTURE_STAGES):
+			var combo_index := base_combo_index + texture_stage
+			if combo_index < 0 or combo_index >= texture_transform_combos.size():
+				continue
+			var transform_index := int(texture_transform_combos[combo_index])
+			if transform_index < 0 or transform_index >= texture_transforms.size():
+				continue
+			var texture_transform: Dictionary = (
+				texture_transforms[transform_index]
+				if texture_transforms[transform_index] is Dictionary
+				else {}
+			)
+			var rotation: Vector4 = texture_transform.get(
+				"rotation",
+				Vector4(1.0, 0.0, 0.0, 1.0)
+			)
+			if not rotation.is_equal_approx(Vector4(1.0, 0.0, 0.0, 1.0)):
+				return true
+			if absf(float(texture_transform.get("rotation_speed", 0.0))) > UV_ROTATION_SPEED_EPSILON:
+				return true
+	return false

src/render/m2/m2_runtime_mesh_rebuild_classifier.gd.uid

@@ -0,0 +1 @@
+uid://breu8vpmm88en