VR Teleport

A C++ plugin for VR teleportation in Unreal Engine

github project

About:

VRTeleportComponent is a C++ plugin for Unreal Engine that allows adding teleportation capabilities to any pawn in the context of VR. The plugin implements an engine component (VRTeleportComponent) which automatically takes care of a number of things involved in teleportation:

  • ray-casting and hit-testing (in line or projectile/parabola mode).
  • avoiding blocking the ray cast with its owning actor.
  • checking for the hit point being orthogonal to the ground.
  • showing and hiding a marker of the teleport location.
  • accounting for camera offset from the VR bounds when teleporting to a new target location.
  • providing a default animation for teleportation (fade out and translate).

The component also handles replication / authority for multiplayer scenarios and has a number of events which can be implemented in either C++ or Blueprints to further customize its behavior.

Video 1. VR teleport component demonstration.

Architecture:

The component can be thought of as a state machine with three states:

Idle
The component is in standby.
Probing
The component periodically ray-casts and hit-tests against objects in the world, probing for a suitable location (i.e. orthogonal to the ground) to potentially teleport to.
Teleporting
The component translates the owning pawn to an arbitrary location.

Figure 1 shows the main methods which trigger transitioning between states (above bar) and the delegate events (below bar) dispatched on each transition.

Figure 1. Teleport component state machine. Transitions are triggered by methods (text above bars) or automatically (epsilon). Transition delegates (text below bars) allow customizing the component's behavior.

Methods that trigger transitions can only execute on the server, to prevent clients in a multiplayer environment from cheating. Delegates however are dispatched to all replicated versions of a pawn. This is to avoid costly syncing between server and clients (such as when ray-tracing during probing). Instead, clients use their own resources while probing and teleporting and the server ultimately replicates the final position of the pawn to all clients.

Setup and Customization:

A basic setup (as the one in Video 1) can be achieved in 4 steps:

  1. Start with a pawn with a camera and motion controller, with a cube for the hand mesh (Figure 2).
  2. Add the teleport component as a child of the motion controller, so it follows the controller (Figure 3).
  3. Add a decal as a child of the teleport component; the component uses its first child as a marker, if one is present (Figure 3).
  4. Connect a controller input (i.e.: the pad in the HTC Vive wand) to the appropriate methods of the teleport component (Figure 4).
Figure 2. Pawn without teleport component.
Figure 3. Pawn with teleport component and decal as a marker.
Figure 4. Connecting a controller input (i.e.: HTC Vive wand pad) to the teleport component.

For delegate events with a response, you can set the response parameter ShouldPerformDefaultImplementation to false if you want to bypass the default behavior of the component. An example would be to perform a teleport effect different than the default one:

Figure 5. Bypassing default teleport behavior and implementing custom behavior.