Hi
making an Anim BP to recieve streaming Optitrack data from Motive you add an Optitrack Skeleton node
Dragging off from the Source Skeleton Asset Name or the Streaming Client Origin to quckly create a variable of the correct type (which is common practice in Unreal development) creates a variable but then the animation BP won't work.
instead you need to search for and add the correct variable type from the list.}
this is a bug which has been around for ever here's an image from Unreal 4.27 the 5.3 version looks very similar.
Yes, this is a known issue in Unreal Engine when working with streaming Optitrack data via the Animation Blueprint (Anim BP). Dragging off the Source Skeleton Asset Name or Streaming Client Origin pin to create a variable will indeed generate a variable, but it often defaults to the incorrect type. This results in the Animation Blueprint failing to work properly because Unreal doesn’t always infer the right variable type in these cases.
Correct Approach:
To ensure compatibility, you should manually create the variable with the specific, correct type:
1. Create the Variable Manually: Instead of dragging off to create a variable, open the Variables tab in the Animation Blueprint and manually add a new variable.
2. Select the Correct Type: For Source Skeleton Asset Name, you typically need to select the type Optitrack Skeleton (or a similar type depending on the setup). For Streaming Client Origin, the type should correspond to the streaming origin reference from Optitrack.
Manually setting the type this way ensures that the Blueprint recognizes the variable properly, allowing the Anim BP to function as expected with Optitrack data. This issue has persisted across versions, from Unreal Engine 4.27 through 5.3, and it’s a common workaround among developers using Optitrack with Unreal.
I have previously had similar problems. Open the Animation Blueprint's Variables tab and manually add a new variable as an alternative to dragging off to create one. Optitrack with Unreal is a popular solution for developers using Unreal Engine 4.27 to 5.3.
I just ran into the same thing with 5.3 and was scratching my head for a while. Dragging off the pin and creating a variable seemed like it should work, but yeah, turns out it's assigning the wrong type under the hood.
Manually creating the variable with the correct type from the Variables panel fixed it for me, too. It's a bit of a gotcha if you're used to Unreal's usual workflow. Surprised this hasn't been addressed yet, considering it's been around since 4.27.
