Fix T76566: Fix slow FBX import of long animations.

Note that this patches changes how we insert keyframes, since we cannot
use the `'NEEDED'` option of the slower previous code, we may generate
more keys than needed.

This change gives about 60 times speedup when importing heavy animations
though, so think that trade-of is totally acceptable.

Patch by @Hotox, with some fixes and cleanup by @mont29.

Differential: https://developer.blender.org/D7762

2 files changed, 29 insertions, 6 deletions

diff --git a/io_scene_fbx/__init__.py b/io_scene_fbx/__init__.py
index b935768d..08e95cf9 100644
--- a/io_scene_fbx/__init__.py
+++ b/io_scene_fbx/__init__.py
@@ -21,7 +21,7 @@
 bl_info = {
     "name": "FBX format",
     "author": "Campbell Barton, Bastien Montagne, Jens Restemeier",
-    "version": (4, 20, 3),
+    "version": (4, 21, 0),
     "blender": (2, 81, 6),
     "location": "File > Import-Export",
     "description": "FBX IO meshes, UV's, vertex colors, materials, textures, cameras, lamps and actions",
diff --git a/io_scene_fbx/import_fbx.py b/io_scene_fbx/import_fbx.py
index 1c3447ef..e580a147 100644
--- a/io_scene_fbx/import_fbx.py
+++ b/io_scene_fbx/import_fbx.py
@@ -576,6 +576,14 @@ def blen_read_animations_action_item(action, item, cnodes, fps, anim_offset):
 
     blen_curves = []
     props = []
+    keyframes = {}
+
+    # Add each keyframe to the keyframe dict
+    def store_keyframe(fc, frame, value):
+        fc_key = (fc.data_path, fc.array_index)
+        if not keyframes.get(fc_key):
+            keyframes[fc_key] = []
+        keyframes[fc_key].append((frame, value))
 
     if isinstance(item, Material):
         grpname = item.name
@@ -618,7 +626,7 @@ def blen_read_animations_action_item(action, item, cnodes, fps, anim_offset):
                 value[channel] = v
 
             for fc, v in zip(blen_curves, value):
-                fc.keyframe_points.insert(frame, v, options={'NEEDED', 'FAST'}).interpolation = 'LINEAR'
+                store_keyframe(fc, frame, v)
 
     elif isinstance(item, ShapeKey):
         for frame, values in blen_read_animations_curves_iter(fbx_curves, anim_offset, 0, fps):
@@ -629,7 +637,7 @@ def blen_read_animations_action_item(action, item, cnodes, fps, anim_offset):
                 value = v / 100.0
 
             for fc, v in zip(blen_curves, (value,)):
-                fc.keyframe_points.insert(frame, v, options={'NEEDED', 'FAST'}).interpolation = 'LINEAR'
+                store_keyframe(fc, frame, v)
 
     elif isinstance(item, Camera):
         for frame, values in blen_read_animations_curves_iter(fbx_curves, anim_offset, 0, fps):
@@ -640,7 +648,7 @@ def blen_read_animations_action_item(action, item, cnodes, fps, anim_offset):
                 value = v
 
             for fc, v in zip(blen_curves, (value,)):
-                fc.keyframe_points.insert(frame, v, options={'NEEDED', 'FAST'}).interpolation = 'LINEAR'
+                store_keyframe(fc, frame, v)
 
     else:  # Object or PoseBone:
         if item.is_bone:
@@ -652,7 +660,6 @@ def blen_read_animations_action_item(action, item, cnodes, fps, anim_offset):
         rot_eul_prev = bl_obj.rotation_euler.copy()
         rot_quat_prev = bl_obj.rotation_quaternion.copy()
 
-
         # Pre-compute inverted local rest matrix of the bone, if relevant.
         restmat_inv = item.get_bind_matrix().inverted_safe() if item.is_bone else None
 
@@ -694,8 +701,24 @@ def blen_read_animations_action_item(action, item, cnodes, fps, anim_offset):
             else:  # Euler
                 rot = rot.to_euler(rot_mode, rot_eul_prev)
                 rot_eul_prev = rot
+
+            # Add each keyframe and its value to the keyframe dict
             for fc, value in zip(blen_curves, chain(loc, rot, sca)):
-                fc.keyframe_points.insert(frame, value, options={'NEEDED', 'FAST'}).interpolation = 'LINEAR'
+                store_keyframe(fc, frame, value)
+
+    # Add all keyframe points to the fcurves at once and modify them after
+    for fc_key, key_values in keyframes.items():
+        data_path, index = fc_key
+
+        # Add all keyframe points at once
+        fcurve = action.fcurves.find(data_path=data_path, index=index)
+        num_keys = len(key_values)
+        fcurve.keyframe_points.add(num_keys)
+
+        # Apply values to each keyframe point
+        for kf_point, v in zip(fcurve.keyframe_points, key_values):
+            kf_point.co = v
+            kf_point.interpolation = 'LINEAR'
 
     # Since we inserted our keyframes in 'FAST' mode, we have to update the fcurves now.
     for fc in blen_curves: