Stereoscopic Cubemap Support

Adolar13 · May 13, 2022, 8:07am

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

yaustar · May 13, 2022, 8:59am

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

mvaligursky · May 13, 2022, 9:43am

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:

github.com

playcanvas/engine/blob/27e983374ef4f0af8700e3fa81e1ea4aa488300e/src/scene/renderer/forward-renderer.js#L1359-L1379

      
        
            for (let v = 0; v < views.length; v++) {
                const view = views[v];
            
            
    device.setViewport(view.viewport.x, view.viewport.y, view.viewport.z, view.viewport.w);
            
            
    this.projId.setValue(view.projMat.data);
                this.projSkyboxId.setValue(view.projMat.data);
                this.viewId.setValue(view.viewOffMat.data);
                this.viewInvId.setValue(view.viewInvOffMat.data);
                this.viewId3.setValue(view.viewMat3.data);
                this.viewProjId.setValue(view.projViewOffMat.data);
                this.viewPosId.setValue(view.position);
            
            
    if (v === 0) {
                    this.drawInstance(device, drawCall, mesh, style, true);
                } else {
                    this.drawInstance2(device, drawCall, mesh, style);
                }
            
            
    this._forwardDrawCalls++;
            }

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.