Frequently Asked Questions

I’ve added the plugin to the plugins folder of my project and it says ‘[ProjectName] cannot be compiled’. What do I do?

This is a quirk of Unreal projects that don’t have any C++ code in them (blueprint only projects). To rebuild the Ultraleap Tracking plugin, the project must be converted to a C++ project. To convert the project:

  • Rename the Plugins folder to Plugin to prevent it being used on loading the project

  • Open your project (.uproject) file

  • Go to File->Add C++ class and add an empty C++ class to the project. It doesn’t matter what it’s named
  • Now, exit your project, rename the Plugin folder to Plugins

  • Right click on your project .uproject file and choose Generate Visual Studio Project Files

  • Open the generated solution (.sln) and build it

  • You’ll now be able to open your .uproject file and edit it as normal.

How do I set up the hand meshes so that the fingers collide with other objects in the scene?

Create a Physics Asset on the hand mesh. Unreal have a guide on how to do this: Skeletal Mesh Actors | Unreal Engine Documentation. See the Collision section for details.

How do I modify a single joint/bone that has been mapped slightly wrongly?

In the anim graph of your anim blueprint, drag a connection out of the Ultraleap Modify Mapped Bones node and add a Transform (Modify) bone node. Now edit the Transform node settings to change whichever bone you want to modify in the skeleton.

How do I clear a bone mapping back to none in the details view?

Go to the Edit Defaults tab and click the yellow reset arrow next to the bone you want to reset.

Why don’t the different hand meshes line up perfectly?

This is due to differences in each imported rigged model and whether or not metacarpal joints are included/mapped.

How do I make my ring finger and little/pinky finger collide with objects in the scene?

By default, the Interaction Engine pawn has collisions turned off for these fingers to prevent accidentally hitting buttons/objects. To enable collisions the Physics asset for the left and right hands must be modified.

  • Open the IELowPloy_Rigged_Hand_Left_Physics asset from InteractionEngine/Pawn/IELowPoly_Rigged_Hand_Left_Physics.uasset
  • Ctrl/Multi-Select all the joints for the Ring and Pinky fingers
  • Set the Collision Response to Enabled

  • Repeat for the IELowPloy_Rigged_Hand_Right_Physics asset

In addition, if you want to enable the smaller fingers so that they can push buttons, edit the IEButtonGrabComponent Disabled Bones list and remove Pinky and Ring.