Hello there,
I came up with some suggestions about Spine plugin for UE4.

SpineBoneDrive component and SpineBoneFollower component

• Properties UsePosition/UseRotation/UseScale are not used in the cpp code.
• Target property should be "EditInstanceOnly" because you cannot set an instance through the blueprint editor.
• I made a test with the anim "aim" and set the "Target" property with the bone "crosshair"
  the result is not good as you can see. https://ibb.co/qNbSFVr

Editor

• The render in editor seems broken, but work perfectly in PIE.
  https://ibb.co/QFGMXYP

Improvements and features

• Spine Gameplay Debugger category with animation state, number of tracks and their indexes.
  https://docs.unrealengine.com/en-US/Gameplay/Tools/GameplayDebugger/index.html
• Integration of spine in the sequencer (manipulate bones, animations, etc...) https://docs.unrealengine.com/en-US/Engine/Sequencer/Overview/index.html
• Better blending when removing track (I made a gif comparison between UE and Unity, Unity is way better)
  (Unreal https://ibb.co/1K2w4Jj vs Unity https://ibb.co/P5dV7mw)

I tested the Unity version and is definitely more polish than UE.

• We cannot set the rotation of a bone (in blueprint).
• Most of the example maps doesn't works.
• "Mix data" and "default mix" properties in "Spine Skeleton Data Asset" are not working.

The 2D solution looks fantastic, but need a little bit of more stability and functionality.
Because of a non maintained built-in Paper2D plugin by Epic, Unreal community really looking for a functional 2D solution.
Anyway thank you for your work.

Thanks for the answers.

So, about the BoneDriver and BoneFollower component I found the problem.
The scale of my skeleton actor was (X : 0.5 ; Y : 0.333 ; Z : 0.5) and because of the value 0.333 the location of the crosshair wasn't good.
I don't know if it's a bug or normal behavior when the scale values are uniform.

most examples don't work
When I said they're not working, I mean the behavior of the examples maps not working,
especially the behavior of the maps 03-multiple-tracks-and-events and 05-driving-bones.

Here is my project https://filebin.net/q0kqwc4fbsiunox3/spine-ue4.rar?t=xlhei710 with a map called "MAP_Test".

I fixed the "03-multiple-tracks-and-events" and "05-driving-bones" maps if you want to compare with your github repository project.
Also the blueprints have some comments about the reason why they are not working.

Blending: that's a matter of setting the mix duration between animation switches and not a bug. Is that a scene you created yourself?
Is it related to the default mix array in the skeleton data asset ? If so I tried with this array entry

From => "idle"
To => "aim"
Mix => 0.5

If it's not that, how can I change the setting of the mix duration ?

Editor
The bad render gone when I cleaned the project, so for now it's working and I'll tell you if the error occurs again.

Additional Infos
Unreal version: 4.22
Spine2D plugin version: 3.8

Hello,

So I tried with the right animations for the skeleton asset mixing data but still not working.
I tried with the TrackEntry and it didn't worked too.

But I noticed when I release the left mouse button the AddEmptyAnimation node with a custom mixduration worked.

My blueprint : https://ibb.co/6vJNh5d
My skeleton asset : https://ibb.co/W0FTybx
The render : https://ibb.co/PF3mYs9

Other bugs I noticed :

• When the engine is launch the render component looks blurry and I need to zoom in the component to remove the blurry artifact.
  https://ibb.co/VCqgbmy

• If the "Target" pin is empty on the "AddEmptyAnimation" node and I compile the blueprint then the editor crash.
  That probably happen on others "Add/Set Animation" nodes.
  https://gifyu.com/image/kEi4