Lacey Gold's FIEA Art Blog: Medusa VR - Setting up gaze interaction

For our VR project, I want to create an interaction with Medusa based on the player's gaze. Working with a Meta Quest 2, I was a bit limited in being unable to track eye movement, but fortunately, I'm able to cast a ray from the position of the VR headset that triggers an interaction if the ray hits a specific object.

The first step is to get the Pawn Blueprint for the VR player. We'll create a function that casts the ray from the player's camera called 'Line Trace Forward'. Into the 'Line Trace By Channel' function, we bring in the camera's world location for the starting position, and calculate the end point by adding together the world location and the forward movement from the world rotation. To check if the rays are casting correctly, select the 'Draw Debug Type' dropdown menu in the 'Line Trace By Channel' function and select, 'For Duration.'

Line Trace Forward Function in VR_Pawn

Next, we're gonna create another function for the VR player that tracks the gaze and where the ray hits. We'll feed the 'Line Trace Forward' function through 'Break Hit Result' to say if we hit something, we'll send the object it hits to another blueprint I'll discuss later, and if the object the ray cast hit is an object that we can interact with, we'll send that data to our next blueprint, 'Interact.'

Basic Gaze Function in VR_Pawn

This function double checks for us if the object is valid and if so, to bring it to the 'Activate' function in our next blueprint class.

Interact Function in VR_Pawn

Next we need a parent blueprint class that will allow us to create multiple children of different interactable objects. I've titled it, BP_GazeInteractable. Inside this parent class, all we need to do is create an 'Activate' function. From there, we create a child off of that blueprint. In our child blueprint, we'll bring the static mesh of the object we want to be interactable, under the 'Components' tab. Additionally under that tab, we'll add a 'Rotating Movement' component as the action we'll take when activated.

In our 'Activate' blueprint, we'll create a boolean to hold the true/false values of if the cube can rotate, with true activating the rotation, and false halting it. In the 'Select' node, leave 'False' as it is, and change the Z value under 'True' to 180.