io_scene_fbx/export_fbx_bin.py

@@ -2260,17 +2260,20 @@ def fbx_animations_do(scene_data, ref_id, f_start, f_end, start_zero, objects=No
     currframes = np.arange(f_start, np.nextafter(f_end, np.inf), step=bake_step)
     real_currframes = currframes - f_start if start_zero else currframes
 
-    # Get all animated values
+    # Generator that yields the animated values of each frame in order.
     def frame_values_gen():
-        # Iterate through each frame and yield the values for that frame.
+        # Precalculate integer frames and subframes.
         int_currframes = currframes.astype(int)
         subframes = currframes - int_currframes
+
         # Create simpler iterables that return only the values we care about.
         animdata_shapes_only = [shape for _anim_shape, _me, shape in animdata_shapes.values()]
         animdata_cameras_only = [camera for _anim_camera_lens, _anim_camera_focus_distance, camera
                                  in animdata_cameras.values()]
         # Previous frame's rotation for each object in animdata_ob, this will be updated each frame.
         animdata_ob_p_rots = p_rots.values()
+
+        # Iterate through each frame and yield the values for that frame.
         # Iterating .data, the memoryview of an array, is faster than iterating the array directly.
         for real_currframe, int_currframe, subframe in zip(real_currframes.data, int_currframes.data, subframes.data):
             scene.frame_set(int_currframe, subframe=subframe)
@@ -2298,59 +2301,55 @@ def fbx_animations_do(scene_data, ref_id, f_start, f_end, start_zero, objects=No
                 yield camera.lens
                 yield camera.dof.focus_distance
 
-    # Calculating the total expected number of values reduces memory allocations while iterating and ensures the array
+    # Providing `count` to np.fromiter pre-allocates the array, avoiding extra memory allocations while iterating.
-    # ends up the size we're expecting.
+    num_ob_values = len(animdata_ob) * 9  # Location, rotation and scale, each of which have x, y, and z components
-    num_ob_loc_values = num_ob_rot_values = num_ob_scale_values = 3
+    num_shape_values = len(animdata_shapes)  # Only 1 value per shape key
-    num_values_per_ob = num_ob_loc_values + num_ob_rot_values + num_ob_scale_values
+    num_camera_values = len(animdata_cameras) * 2  # Focal length (`.lens`) and focus distance
-    num_ob_values = len(animdata_ob) * num_values_per_ob
-    num_shape_values = len(animdata_shapes)
-    num_values_per_camera = 2
-    num_camera_values = len(animdata_cameras) * num_values_per_camera
     num_values_per_frame = num_ob_values + num_shape_values + num_camera_values
     num_frames = len(real_currframes)
-    total_num_values = num_frames * num_values_per_frame
+    all_values_flat = np.fromiter(frame_values_gen(), dtype=float, count=num_frames * num_values_per_frame)
-    all_values = np.fromiter(frame_values_gen(), dtype=np.float64, count=total_num_values)
+
+    # Restore the scene's current frame.
     scene.frame_set(back_currframe, subframe=0.0)
 
-    # View as each column being the values for a single frame and each row being all values for a single property in a
+    # View such that each column is all values for a single frame and each row is all values for a single curve.
-    # curve.
+    all_values = all_values_flat.reshape(num_frames, num_values_per_frame).T
-    all_values = all_values.reshape(num_frames, -1).T
     # Split into views of the arrays for each curve type.
     split_at = [num_ob_values, num_shape_values, num_camera_values]
+    # For unequal sized splits, np.split takes indices to split at, which can be acquired through a cumulative sum
+    # across the list.
     # The last value isn't needed, because the last split is assumed to go to the end of the array.
-    split_at = split_at[:-1]
+    split_at = np.cumsum(split_at[:-1])
-    # For uneven splits, np.split takes indices to split at, which can be acquired through a cumulative sum across the
-    # list.
-    split_at = np.cumsum(split_at)
     all_ob_values, all_shape_key_values, all_camera_values = np.split(all_values, split_at)
 
-    # Set location/rotation/scale curves
+    # Set location/rotation/scale curves.
-    # Further split into views of the arrays for each object.
+    # Split into equal sized views of the arrays for each object.
-    num_animdata_ob = len(animdata_ob)
+    split_into = len(animdata_ob)
-    all_ob_values = np.split(all_ob_values, num_animdata_ob) if num_animdata_ob else ()
+    per_ob_values = np.split(all_ob_values, split_into) if split_into > 0 else ()
-    for (anim_loc, anim_rot, anim_scale), ob_values in zip(animdata_ob.values(), all_ob_values):
+    for (anim_loc, anim_rot, anim_scale), ob_values in zip(animdata_ob.values(), per_ob_values):
-        # Further split into views of the location, rotation and scaling arrays.
+        # Split again into equal sized views of the location, rotation and scaling arrays.
         loc_xyz, rot_xyz, sca_xyz = np.split(ob_values, 3)
-        # In-place convert to degrees.
+        # In-place convert from Blender rotation to FBX rotation.
         np.rad2deg(rot_xyz, out=rot_xyz)
 
         anim_loc.set_keyframes(real_currframes, loc_xyz)
         anim_rot.set_keyframes(real_currframes, rot_xyz)
         anim_scale.set_keyframes(real_currframes, sca_xyz)
 
-    # Set shape key curves
+    # Set shape key curves.
+    # There's only one array per shape key, so there's no need to split `all_shape_key_values`.
     for (anim_shape, _me, _shape), shape_key_values in zip(animdata_shapes.values(), all_shape_key_values):
         # In-place convert from Blender Shape Key Value to FBX Deform Percent.
         shape_key_values *= 100.0
         anim_shape.set_keyframes(real_currframes, shape_key_values)
 
-    # Set camera curves
+    # Set camera curves.
-    # Further split into views of the arrays for each camera.
+    # Split into equal sized views of the arrays for each camera.
-    num_animdata_cameras = len(animdata_cameras)
+    split_into = len(animdata_cameras)
-    all_camera_values = np.split(all_camera_values, num_animdata_cameras) if num_animdata_cameras else ()
+    per_camera_values = np.split(all_camera_values, split_into) if split_into > 0 else ()
-    for (anim_camera_lens, anim_camera_focus_distance, camera), camera_values in zip(animdata_cameras.values(), all_camera_values):
+    zipped = zip(animdata_cameras.values(), per_camera_values)
-        lens_values, focus_distance_values = camera_values
+    for (anim_camera_lens, anim_camera_focus_distance, _camera), (lens_values, focus_distance_values) in zipped:
-        # In-place convert from Blender to FBX
+        # In-place convert from Blender focus distance to FBX.
         focus_distance_values *= (1000 * gscale)
         anim_camera_lens.set_keyframes(real_currframes, lens_values)
         anim_camera_focus_distance.set_keyframes(real_currframes, focus_distance_values)