feat: Add VRM Blender addon with complete import/export functionality

- Add core VRM addon infrastructure with manifest and registration
- Add common utilities module with file system, logging, and conversion helpers
- Add human bone mapper with support for multiple rigging standards (Mixamo, MMD, Unreal, Rigify, etc.)
- Add VRM 0.x and 1.x format support with property groups and handlers
- Add editor UI panels for VRM metadata, spring bones, and MToon materials
- Add exporter with glTF2 extension support for VRM format serialization
- Add importer with scene reconstruction and armature generation
- Add MToon shader support with auto-setup and material migration
- Add spring bone physics simulation with constraint handling
- Add node constraint editor for advanced rigging control
- Add comprehensive validation and error handling with user dialogs
- Add scene watcher for real-time property synchronization
- Add workspace management and preference system
- Include Python cache files and Blender manifest configuration
- This is the initial commit establishing the complete VRM addon ecosystem for Blender

common/rotation.py

@@ -0,0 +1,87 @@
+# SPDX-License-Identifier: MIT OR GPL-3.0-or-later
+from typing import Final, Union
+
+from bpy.types import (
+    Object,
+    PoseBone,
+)
+from mathutils import Quaternion
+
+from .logger import get_logger
+
+logger = get_logger(__name__)
+
+
+ROTATION_MODE_QUATERNION: Final = "QUATERNION"
+ROTATION_MODE_AXIS_ANGLE: Final = "AXIS_ANGLE"
+ROTATION_MODE_EULER: Final = ("XYZ", "XZY", "YXZ", "YZX", "ZXY", "ZYX")
+
+
+def get_rotation_as_quaternion(
+    object_or_pose_bone: Union[Object, PoseBone],
+) -> Quaternion:
+    if object_or_pose_bone.rotation_mode == ROTATION_MODE_QUATERNION:
+        return object_or_pose_bone.rotation_quaternion.copy()
+
+    if object_or_pose_bone.rotation_mode == ROTATION_MODE_AXIS_ANGLE:
+        axis_x, axis_y, axis_z, angle = object_or_pose_bone.rotation_axis_angle
+        return Quaternion((axis_x, axis_y, axis_z), angle)
+
+    if object_or_pose_bone.rotation_mode in ROTATION_MODE_EULER:
+        return object_or_pose_bone.rotation_euler.to_quaternion()
+
+    logger.error(
+        "Unexpected rotation mode for %s %s: %s",
+        type(object_or_pose_bone),
+        object_or_pose_bone.name,
+        object_or_pose_bone.rotation_mode,
+    )
+
+    return Quaternion()
+
+
+def set_rotation_without_mode_change(
+    object_or_pose_bone: Union[Object, PoseBone], quaternion: Quaternion
+) -> None:
+    if object_or_pose_bone.rotation_mode == ROTATION_MODE_QUATERNION:
+        object_or_pose_bone.rotation_quaternion = quaternion.copy()
+        return
+
+    if object_or_pose_bone.rotation_mode == ROTATION_MODE_AXIS_ANGLE:
+        axis, angle = quaternion.to_axis_angle()
+        object_or_pose_bone.rotation_axis_angle = [axis.x, axis.y, axis.z, angle]
+        return
+
+    if object_or_pose_bone.rotation_mode in ROTATION_MODE_EULER:
+        object_or_pose_bone.rotation_euler = quaternion.to_euler(
+            object_or_pose_bone.rotation_mode
+        )
+        return
+
+    logger.error(
+        "Unexpected rotation mode for %s %s: %s",
+        type(object_or_pose_bone),
+        object_or_pose_bone.name,
+        object_or_pose_bone.rotation_mode,
+    )
+
+
+def insert_rotation_keyframe(
+    object_or_pose_bone: Union[Object, PoseBone], *, frame: int
+) -> None:
+    if object_or_pose_bone.rotation_mode == ROTATION_MODE_QUATERNION:
+        data_path = "rotation_quaternion"
+    elif object_or_pose_bone.rotation_mode == ROTATION_MODE_AXIS_ANGLE:
+        data_path = "rotation_axis_angle"
+    elif object_or_pose_bone.rotation_mode in ROTATION_MODE_EULER:
+        data_path = "rotation_euler"
+    else:
+        logger.error(
+            "Unexpected rotation mode for %s %s: %s",
+            type(object_or_pose_bone),
+            object_or_pose_bone.name,
+            object_or_pose_bone.rotation_mode,
+        )
+        return
+
+    object_or_pose_bone.keyframe_insert(data_path, frame=frame)