Enable post-processing in VR

src/renderers/WebGLRenderer.js

@@ -72,7 +72,7 @@
 			powerPreference = 'default',
 			failIfMajorPerformanceCaveat = false,
 			reverseDepthBuffer = false,
 			multiviewStereo = false,
 		} = parameters;
 
 		this.isWebGLRenderer = true;
@@ -2266,7 +2266,7 @@
 
 					if ( ! warned ) {
 
 						console.warn( "THREE.WebGLRenderer.setTexture2D: don't use render targets as textures. Use their .texture property instead." );
 						warned = true;
 
 					}
@@ -2335,6 +2335,13 @@
 		const _scratchFrameBuffer = _gl.createFramebuffer();
 		this.setRenderTarget = function ( renderTarget, activeCubeFace = 0, activeMipmapLevel = 0 ) {
 
+			// Render to base layer instead of canvas in WebXR
+			if ( renderTarget === null && this.xr.isPresenting ) {
+
+				renderTarget = this.xr.getRenderTarget();
+
+			}
+
 			_currentRenderTarget = renderTarget;
 			_currentActiveCubeFace = activeCubeFace;
 			_currentActiveMipmapLevel = activeMipmapLevel;

src/renderers/webxr/WebXRManager.js

@@ -248,6 +248,12 @@
 
 		};
 
+		this.getRenderTarget = function () {
+
+			return newRenderTarget;
+
+		};
+
 		this.getFrame = function () {
 
 			return xrFrame;
@@ -406,10 +412,10 @@
 
 				return session.environmentBlendMode;
 
 			}
 		}
 
 		this.addLayer = function(layer) {
 			if (!window.XRWebGLBinding || !this.layersEnabled || !session) { return; }
 
 			layers.push( layer );