Stereoscopic Cubemap Support

Help & Support
1

Hey,
I wanted to know if there is a way to use stereoscopic cubemaps in playcanvas for use in VR/XR?
I was thinking about a per Eye layer to use a different mapped sphere on each layer and display the corresponding cubemap. But I don’t know if this can be achieved.

Best
Paul

2

Hmmm, I’ve not come across this myself. There’s no layer on a per eye level on the public API level. You may have to start digging into the engine internals at that point

3

I agree, there’s no direct support for this.

In the engine, when rendering each draw call, we swap some uniforms (mostly camera related) for each view (eye). See the code here:

Perhaps you could do a custom shader / chunk and use the viewPos to detect left vs right, and output color from different cubemap or similar.

2 Likes
4

Thanks, although almost a year later I came back here and implemented a shader chunk as @mvaligursky suggested. I figured this might be helpful for someone trying to do the same:

// Define the texture to use for the left eye
uniform sampler2D _leftTexture;

// Define the texture to use for the right eye
uniform sampler2D _rightTexture;

uniform bool _singleImage;

uniform vec3 _viewDir;
uniform vec3 _viewPos;

void getEmission() {
    vec2 uv = $UV;
    vec4 textureColor;

    if(_singleImage){
        uv.y = uv.y * 0.5;
    }

    // use reference position and calc vector to viewpos
    vec3 vectorAB = view_position - _viewPos;

    // Calculate the cross product between the direction vector and the vector formed by the two positions
    vec3 cross = cross(_viewDir, vectorAB);

    if (cross.y > 0.0) {
        // position is to the left of the direction
        textureColor = texture2D(_leftTexture, uv);
    } else {
        // position is to the right of the direction
        if(_singleImage){
            uv.y += 0.5;
            textureColor = texture2D(_leftTexture, uv);
        } else {
            textureColor = texture2D(_rightTexture, uv);
        }
    }

    dEmission = textureColor.rgb;
}
3 Likes
5

Thanks for sharing the shader code!