diff --git a/io_scene_gltf2/__init__.py b/io_scene_gltf2/__init__.py
index 5c8872f3d2052d8f3435b1c9f67524b8315cc98f..be8aa8edf5b37118db1f632d641071870f2edd3e 100755
--- a/io_scene_gltf2/__init__.py
+++ b/io_scene_gltf2/__init__.py
@@ -4,7 +4,7 @@
bl_info = {
'name': 'glTF 2.0 format',
'author': 'Julien Duroure, Scurest, Norbert Nopper, Urs Hanselmann, Moritz Becher, Benjamin SchmithĂĽsen, Jim Eckerlein, and many external contributors',
- "version": (3, 3, 15),
+ "version": (3, 3, 16),
'blender': (3, 3, 0),
'location': 'File > Import-Export',
'description': 'Import-Export as glTF 2.0',
diff --git a/io_scene_gltf2/blender/exp/gltf2_blender_gather_animation_sampler_keyframes.py b/io_scene_gltf2/blender/exp/gltf2_blender_gather_animation_sampler_keyframes.py
index e1ed19ea18a81a57be7f4d59330693b5ded173cf..ba331b74ddbb4da13c7660183e98083b7a63e72a 100755
--- a/io_scene_gltf2/blender/exp/gltf2_blender_gather_animation_sampler_keyframes.py
+++ b/io_scene_gltf2/blender/exp/gltf2_blender_gather_animation_sampler_keyframes.py
@@ -398,11 +398,17 @@ def gather_keyframes(blender_obj_uuid: str,
key.set_first_tangent()
else:
# otherwise construct an in tangent coordinate from the keyframes control points. We intermediately
- # use a point at t-1 to define the tangent. This allows the tangent control point to be transformed
- # normally
+ # use a point at t+1 to define the tangent. This allows the tangent control point to be transformed
+ # normally, but only works for locally linear transformation. The more non-linear a transform, the
+ # more imprecise this method is.
+ # We could use any other (v1, t1) for which (v1 - v0) / (t1 - t0) equals the tangent. By using t+1
+ # for both in and out tangents, we guarantee that (even if there are errors or numerical imprecisions)
+ # symmetrical control points translate to symmetrical tangents.
+ # Note: I am not sure that linearity is never broken with quaternions and their normalization.
+ # Especially at sign swap it might occure that the value gets negated but the control point not.
+ # I have however not once encountered an issue with this.
key.in_tangent = [
- c.keyframe_points[i].co[1] + ((c.keyframe_points[i].co[1] - c.keyframe_points[i].handle_left[1]
- ) / (frame - frames[i - 1]))
+ c.keyframe_points[i].co[1] + (c.keyframe_points[i].handle_left[1] - c.keyframe_points[i].co[1]) / (c.keyframe_points[i].handle_left[0] - c.keyframe_points[i].co[0])
for c in channels if c is not None
]
# Construct the out tangent
@@ -410,12 +416,10 @@ def gather_keyframes(blender_obj_uuid: str,
# end out-tangent should become all zero
key.set_last_tangent()
else:
- # otherwise construct an in tangent coordinate from the keyframes control points. We intermediately
- # use a point at t+1 to define the tangent. This allows the tangent control point to be transformed
- # normally
+ # otherwise construct an in tangent coordinate from the keyframes control points.
+ # This happens the same way how in tangents are handled above.
key.out_tangent = [
- c.keyframe_points[i].co[1] + ((c.keyframe_points[i].handle_right[1] - c.keyframe_points[i].co[1]
- ) / (frames[i + 1] - frame))
+ c.keyframe_points[i].co[1] + (c.keyframe_points[i].handle_right[1] - c.keyframe_points[i].co[1]) / (c.keyframe_points[i].handle_right[0] - c.keyframe_points[i].co[0])
for c in channels if c is not None
]
diff --git a/io_scene_gltf2/blender/exp/gltf2_blender_gather_animation_samplers.py b/io_scene_gltf2/blender/exp/gltf2_blender_gather_animation_samplers.py
index 1ee98a29f91348568da0c681b21d7854e3149095..5c8011ed516174313efa036f01b7f2d8dfc59617 100755
--- a/io_scene_gltf2/blender/exp/gltf2_blender_gather_animation_samplers.py
+++ b/io_scene_gltf2/blender/exp/gltf2_blender_gather_animation_samplers.py
@@ -414,6 +414,7 @@ def __gather_output(channels: typing.Tuple[bpy.types.FCurve],
transform = parent_inverse
values = []
+ fps = bpy.context.scene.render.fps
for keyframe in keyframes:
# Transform the data and build gltf control points
value = gltf2_blender_math.transform(keyframe.value, target_datapath, transform, need_rotation_correction)
@@ -426,11 +427,11 @@ def __gather_output(channels: typing.Tuple[bpy.types.FCurve],
in_tangent = gltf2_blender_math.transform(keyframe.in_tangent, target_datapath, transform, need_rotation_correction)
if is_yup and blender_object_if_armature is None:
in_tangent = gltf2_blender_math.swizzle_yup(in_tangent, target_datapath)
- # the tangent in glTF is relative to the keyframe value
+ # the tangent in glTF is relative to the keyframe value and uses seconds
if not isinstance(value, list):
- in_tangent = value - in_tangent
+ in_tangent = fps * (in_tangent - value)
else:
- in_tangent = [value[i] - in_tangent[i] for i in range(len(value))]
+ in_tangent = [fps * (in_tangent[i] - value[i]) for i in range(len(value))]
keyframe_value = gltf2_blender_math.mathutils_to_gltf(in_tangent) + keyframe_value # append
if keyframe.out_tangent is not None:
@@ -438,11 +439,11 @@ def __gather_output(channels: typing.Tuple[bpy.types.FCurve],
out_tangent = gltf2_blender_math.transform(keyframe.out_tangent, target_datapath, transform, need_rotation_correction)
if is_yup and blender_object_if_armature is None:
out_tangent = gltf2_blender_math.swizzle_yup(out_tangent, target_datapath)
- # the tangent in glTF is relative to the keyframe value
+ # the tangent in glTF is relative to the keyframe value and uses seconds
if not isinstance(value, list):
- out_tangent = value - out_tangent
+ out_tangent = fps * (out_tangent - value)
else:
- out_tangent = [value[i] - out_tangent[i] for i in range(len(value))]
+ out_tangent = [fps * (out_tangent[i] - value[i]) for i in range(len(value))]
keyframe_value = keyframe_value + gltf2_blender_math.mathutils_to_gltf(out_tangent) # append
values += keyframe_value