FBX exporter doesn't export Constant Interpolation keyframes #76928

New Issue

Justin Jensen · 2020-05-21T00:53:22+02:00

Justin Jensen commented

2020-05-21 00:53:22 +02:00

System Information
Operating system: Windows 10 Pro
Graphics card: NVidia Quadro M1200

Blender Version
Broken: 2.82a

Short description of error
The FBX exporter does not export Constant Interpolation keyframes. Instead, they're converted to Linear Interpolation

Exact steps for others to reproduce the error
Open the default scene.
Add a few location keyframes to the cube
Change each keyframe's interpolation type to Constant
Export as FBX
Import into Unity or back into Blender. The keyframes now have Linear Interpolation

**System Information** Operating system: Windows 10 Pro Graphics card: NVidia Quadro M1200 **Blender Version** Broken: 2.82a **Short description of error** The FBX exporter does not export Constant Interpolation keyframes. Instead, they're converted to Linear Interpolation **Exact steps for others to reproduce the error** Open the default scene. Add a few location keyframes to the cube Change each keyframe's interpolation type to Constant Export as FBX Import into Unity or back into Blender. The keyframes now have Linear Interpolation

Justin Jensen commented

2020-05-21 00:53:22 +02:00

Added subscriber: @JustinJensen

blender-admin commented

2020-05-21 00:53:22 +02:00

#94855 was marked as duplicate of this issue

Germano Cavalcante commented

2020-05-21 22:53:09 +02:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2020-05-21 22:53:09 +02:00

Could you provide a simple file showing the problem?

Justin Jensen commented

2020-05-22 05:54:51 +02:00

simple_constant_interpolation_example.blend

simple_constant_interpolation_example.fbx

I've attached two files:
The first is a .blend file with an extremely simple animation. I want the cube to jump to the right on frame 20, then back to the origin on frame 40. No interpolation.
The second file is this cube exported to FBX. Upon first inspection, it kind of looks like the keyframes use Constant interpolation, but it's actually just two keyframes on adjacent frames with linear interpolation between them. This is a problem when I bring this 24fps animation into a 60fps application like Unity.

[simple_constant_interpolation_example.blend](https://archive.blender.org/developer/F8546944/simple_constant_interpolation_example.blend) [simple_constant_interpolation_example.fbx](https://archive.blender.org/developer/F8546943/simple_constant_interpolation_example.fbx) I've attached two files: The first is a .blend file with an extremely simple animation. I want the cube to jump to the right on frame 20, then back to the origin on frame 40. No interpolation. The second file is this cube exported to FBX. Upon first inspection, it kind of looks like the keyframes use Constant interpolation, but it's actually just two keyframes on adjacent frames with linear interpolation between them. This is a problem when I bring this 24fps animation into a 60fps application like Unity.

Richard Antalik commented

2020-05-25 01:05:33 +02:00

Added subscribers: @dfelinto, @iss

Richard Antalik commented

2020-05-25 01:05:33 +02:00

This looks like a limitation of exporting script. By doing some search for this I have found 96a5167969 implementing this feature but it has been reverted. I am not familiar with fbx format, so I can't see immediately what the issue was.

It's not clear to me if you wanted to have a go at implementing this. If you do, you can discuss possible solutions on https:*devtalk.blender.org or ask @dfelinto on https:*blender.chat/channel/blender-coders

Otherwise we could consider this a known issue or close as accidental feature request.

This looks like a limitation of exporting script. By doing some search for this I have found 96a5167969 implementing this feature but it has been reverted. I am not familiar with fbx format, so I can't see immediately what the issue was. It's not clear to me if you wanted to have a go at implementing this. If you do, you can discuss possible solutions on https:*devtalk.blender.org or ask @dfelinto on https:*blender.chat/channel/blender-coders Otherwise we could consider this a known issue or close as accidental feature request.

Philipp Oeser commented

2020-06-23 12:09:58 +02:00

Added subscriber: @lichtwerk