How to render a stereoscopic side-by-side image in a scene for VR viewing?

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1

What would be the best way to render a stereoscopic side-by-side image in a scene rendered on a plane or (quad) surface for VR viewing? I’m using the Unity version.

Ideally, I’d also like the gameObject to have a billboard property of always facing toward the camera (on the y-axis) since an angle view of a stereoscopic image would distort the stereo camera eye offset.

Best Regards,
Darius

2

To render a stereoscopic side-by-side image in a scene for VR viewing in Unity, you can follow these steps:

  1. Create a Quad: Use a Quad or a plane mesh to display the image. Ensure it has the appropriate size for your stereoscopic images.

  2. Stereoscopic Setup: Load your left and right eye images into textures. You may want to use a shader that can combine them into a single view for the stereoscopic effect.

  3. Billboarding: Implement a script that ensures the Quad always faces the camera along the Y-axis to prevent distortion.

Here’s a sample script to achieve this:

using UnityEngine;

public class StereoscopicBillboard : MonoBehaviour
{
    public Texture leftEyeTexture;
    public Texture rightEyeTexture;
    private Material quadMaterial;

    void Start()
    {
        // Create Quad and its material
        GameObject quad = GameObject.CreatePrimitive(PrimitiveType.Quad);
        quadMaterial = new Material(Shader.Find("Unlit/Texture"));
        quad.GetComponent<Renderer>().material = quadMaterial;

        // Set textures
        quadMaterial.SetTexture("_MainTex", leftEyeTexture);
        // Use custom shader or set a combination for the right eye if needed
    }

    void Update()
    {
        // Make the Quad always face the camera on the Y axis
        Vector3 cameraPosition = Camera.main.transform.position;
        cameraPosition.y = transform.position.y;
        transform.LookAt(cameraPosition);
    }
}

Notes:

  • Adjust the Quad scale based on your desired image size and make sure to assign the proper stereoscopic shader if your implementation requires it.
  • Ensure your textures are properly set in Unity.
  • The leftEyeTexture and rightEyeTexture should be assigned in the Inspector.

Materials and Shaders:

You can create a custom shader that will blend the left and right images or set different materials for left and right eye rendering, depending on how you want to display the stereoscopic effect.

Make sure your cameras are set as stereo cameras in your project settings to properly handle VR rendering.

Feel free to ask if you need more details on specific implementations or concepts!

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3

I don’t want to create a shader. I just want one eye to see the mesh on one layer, and the other eye to see the mesh on another layer. How do I reference the three.js WebXR camera and it’s individual eye cameras for setting layers?

4

To reference the three.js WebXR camera and set individual layers for each eye camera, you can use the following approach. In three.js, the WebXR API allows you to manage different layers (cameras) separately.

Steps:

  1. Create the WebXR Session: Make sure you have initialized the WebXR session properly.
  2. Access the XR Camera: For a WebXR session, use the renderer.xr object to access the individual eye cameras.
  3. Set the Layers for Each Eye: You can use layers to differentiate what each eye sees.

Here’s a simple outline in code:

import { WebXRManager } from 'three/examples/jsm/webxr/WebXRManager';

// Create WebXR session
const xrSession = renderer.xr.getSession();
const leftLayer = new THREE.Layer();
const rightLayer = new THREE.Layer();

// Add content to layers
leftLayer.set(0); // Set left eye layer index
rightLayer.set(1); // Set right eye layer index

// In your render loop
function render() {
    // Set the layers
    renderer.xr.getCamera().layers.enable(leftLayer);
    renderer.xr.getCamera().layers.enable(rightLayer);

    // Your rendering code here
    renderer.render(scene, camera);
}

Explanation:

  1. Layers: Use the THREE.Layer class to create separate layers for each eye.
  2. Set Layers: Use layers.enable() to control which layers each eye camera can see.
  3. Render Loop: Ensure you call the render method during each frame to apply these layers accordingly.

Make sure you enable the XR mode on your renderer and that your environment supports WebXR.

If you have further specific implementations or additional questions, let me know!

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How to get the xr renderer and xr camera from current session?

6
  • this.context.renderer.xr is the three.js WebXRManager
  • this.context.xrCamera is a shorthand for this.renderer?.xr?.getCamera() to get the xr camera
  • this.context.xrSession gives you the current XRSession
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