make XR renderingg more efficient

src/renderers/common/RenderContext.js

@@ -97,6 +97,14 @@ class RenderContext {
 		 */
 		this.clearStencilValue = 1;
 
+		/**
+		 * Whether the depth and stencil should be skipped during copy operations.
+		 *
+		 * @type {Boolean}
+		 * @default true
+		 */
+		this.skipDepthStencilCopy = false;
+
 		/**
 		 * By default the viewport encloses the entire framebuffer If a smaller
 		 * viewport is manually defined, this property is to `true` by the renderer.

src/renderers/common/Renderer.js

@@ -26,7 +26,7 @@ import { Matrix4 } from '../../math/Matrix4.js';
 import { Vector2 } from '../../math/Vector2.js';
 import { Vector4 } from '../../math/Vector4.js';
 import { RenderTarget } from '../../core/RenderTarget.js';
-import { DoubleSide, BackSide, FrontSide, SRGBColorSpace, NoToneMapping, LinearFilter, LinearSRGBColorSpace, HalfFloatType, RGBAFormat, PCFShadowMap } from '../../constants.js';
+import { DoubleSide, BackSide, FrontSide, SRGBColorSpace, NoToneMapping, LinearFilter, LinearSRGBColorSpace, HalfFloatType, RGBAFormat, PCFShadowMap, UnsignedByteType } from '../../constants.js';
 
 /** @module Renderer **/
 
@@ -1128,7 +1128,7 @@ class Renderer {
 			frameBufferTarget = new RenderTarget( width, height, {
 				depthBuffer: depth,
 				stencilBuffer: stencil,
-				type: HalfFloatType, // FloatType
+				type: UnsignedByteType,
 				format: RGBAFormat,
 				colorSpace: LinearSRGBColorSpace,
 				generateMipmaps: false,
@@ -1255,6 +1255,8 @@ class Renderer {
 
 		}
 
+		if ( outputRenderTarget ) renderContext.skipDepthStencilCopy = outputRenderTarget.needsDepthTexture === false;
+
 		//
 
 		let viewport = this._viewport;
@@ -1321,6 +1323,14 @@ class Renderer {
 
 			const renderTargetData = this._textures.get( renderTarget );
 
+			// Do not attach a depth buffer if XR doesn't need one and we're using MSAA
+			if ( renderContext.skipDepthStencilCopy && ( renderContext.sampleCount > 1 ) ) {
+
+				renderTarget.depthBuffer = null;
+				renderTarget.stencilBuffer = null;
+
+			}
+
 			renderContext.textures = renderTargetData.textures;
 			renderContext.depthTexture = renderTargetData.depthTexture;
 			renderContext.width = renderTargetData.width;

src/renderers/common/XRManager.js

@@ -636,6 +636,7 @@ class XRManager extends EventDispatcher {
 					} );
 
 				this._xrRenderTarget.hasExternalTextures = true;
+				this._xrRenderTarget.needsDepthTexture = glBinding.usesDepthValues;
 
 			} else {
 

src/renderers/common/XRRenderTarget.js

@@ -39,6 +39,14 @@ class XRRenderTarget extends RenderTarget {
 		 */
 		this.hasExternalTextures = false;
 
+		/**
+		 * Whether the system compositor needs depth textures.
+		 *
+		 * @type {Boolean}
+		 * @default true
+		 */
+		this.needsDepthTexture = true;
+
 		/**
 		 * Whether a depth buffer should automatically be allocated
 		 * for this XR render target or not.

src/renderers/webgl-fallback/WebGLBackend.js

@@ -1956,7 +1956,7 @@ class WebGLBackend extends Backend {
 
 				}
 
-				if ( descriptor.depthTexture !== null ) {
+				if (( descriptor.depthTexture !== null ) && (!descriptor.skipDepthStencilCopy || ( samples === 0 ))) {
 
 					const textureData = this.get( descriptor.depthTexture );
 					const depthStyle = stencilBuffer ? gl.DEPTH_STENCIL_ATTACHMENT : gl.DEPTH_ATTACHMENT;
@@ -2044,7 +2044,12 @@ class WebGLBackend extends Backend {
 						renderTargetContextData.depthRenderbuffer = depthRenderbuffer;
 
 						const depthStyle = stencilBuffer ? gl.DEPTH_STENCIL_ATTACHMENT : gl.DEPTH_ATTACHMENT;
-						invalidationArray.push( depthStyle );
+
+						if  ( invalidationArray.indexOf( depthStyle ) === -1 ) {
+
+							invalidationArray.push( depthStyle );
+
+						}
 
 					}
 

src/renderers/webgl-fallback/utils/WebGLTextureUtils.js

@@ -261,7 +261,7 @@ class WebGLTextureUtils {
 
 		if ( glFormat === gl.DEPTH_COMPONENT ) {
 
-			if ( glType === gl.UNSIGNED_INT ) internalFormat = gl.DEPTH24_STENCIL8;
+			if ( glType === gl.UNSIGNED_INT ) internalFormat = gl.DEPTH_COMPONENT24;
 			if ( glType === gl.FLOAT ) internalFormat = gl.DEPTH_COMPONENT32F;
 
 		}