WebGLRenderer: Support render target textures in `copyTextureToTexture()`. (#29662)

* WebGLRenderer: Support render target textures in copyTextureToTexture().

* WebGLRenderer: Update `copyTextureToTexture3D()` and docs.

* WebGLRenderer: Attempt to fix `copyTextureToTexture3D()`.

docs/api/en/renderers/WebGLRenderer.html

@@ -383,20 +383,18 @@ document.body.appendChild( renderer.domElement );
 			[method:undefined copyTextureToTexture]( [param:Texture srcTexture], [param:Texture dstTexture], [param:Box2 srcRegion], [param:Vector2 dstPosition], [param:Number level] )
 		</h3>
 		<p>
-			Copies the pixels of a texture in the bounds '[page:Box2 srcRegion]' in
-			the destination texture starting from the given position. Enables access
-			to
-			[link:https://developer.mozilla.org/en-US/docs/Web/API/WebGLRenderingContext/texSubImage2D WebGLRenderingContext.texSubImage2D].
+			Copies the pixels of a texture in the bounds '[page:Box2 srcRegion]' in the destination texture starting from the given position.
+			The `depthTexture` and `texture` property of render targets are supported as well.<br />
+			When using render target textures as `srcTexture` and `dstTexture`, you must make sure both render targets are intitialized e.g. via [page:.initRenderTarget]().
 		</p>
 
 		<h3>
 			[method:undefined copyTextureToTexture3D]( [param:Texture srcTexture], [param:Texture dstTexture], [param:Box3 srcRegion], [param:Vector3 dstPosition], [param:Number level] )
 		</h3>
 		<p>
-			Copies the pixels of a texture in the bounds '[page:Box3 srcRegion]' in
-			the destination texture starting from the given position. Enables access
-			to
-			[link:https://developer.mozilla.org/en-US/docs/Web/API/WebGL2RenderingContext/texSubImage3D WebGL2RenderingContext.texSubImage3D].
+			Copies the pixels of a texture in the bounds '[page:Box3 srcRegion]' in the destination texture starting from the given position.
+			The `depthTexture` and `texture` property of 3D render targets are supported as well.<br />
+			When using render target textures as `srcTexture` and `dstTexture`, you must make sure both render targets are intitialized e.g. via [page:.initRenderTarget]().
 		</p>
 
 		<h3>[method:undefined dispose]( )</h3>

src/renderers/WebGLRenderer.js

@@ -2627,19 +2627,42 @@ class WebGLRenderer {
 			_gl.pixelStorei( _gl.UNPACK_SKIP_PIXELS, minX );
 			_gl.pixelStorei( _gl.UNPACK_SKIP_ROWS, minY );
 
-			if ( srcTexture.isDataTexture ) {
+			if ( srcTexture.isRenderTargetTexture || srcTexture.isDepthTexture ) {
 
-				_gl.texSubImage2D( _gl.TEXTURE_2D, level, dstX, dstY, width, height, glFormat, glType, image.data );
+				const srcTextureProperties = properties.get( srcTexture );
+				const dstTextureProperties = properties.get( dstTexture );
+				const srcRenderTargetProperties = properties.get( srcTextureProperties.__renderTarget );
+				const dstRenderTargetProperties = properties.get( dstTextureProperties.__renderTarget );
+
+				state.bindFramebuffer( _gl.READ_FRAMEBUFFER, srcRenderTargetProperties.__webglFramebuffer );
+				state.bindFramebuffer( _gl.DRAW_FRAMEBUFFER, dstRenderTargetProperties.__webglFramebuffer );
+
+				let mask = _gl.COLOR_BUFFER_BIT;
+
+				if ( srcTexture.isDepthTexture ) mask = _gl.DEPTH_BUFFER_BIT;
+
+				_gl.blitFramebuffer( minX, minY, width, height, dstX, dstY, width, height, mask, _gl.NEAREST );
+
+				state.bindFramebuffer( _gl.READ_FRAMEBUFFER, null );
+				state.bindFramebuffer( _gl.DRAW_FRAMEBUFFER, null );
 
 			} else {
 
-				if ( srcTexture.isCompressedTexture ) {
+				if ( srcTexture.isDataTexture ) {
 
-					_gl.compressedTexSubImage2D( _gl.TEXTURE_2D, level, dstX, dstY, image.width, image.height, glFormat, image.data );
+					_gl.texSubImage2D( _gl.TEXTURE_2D, level, dstX, dstY, width, height, glFormat, glType, image.data );
 
 				} else {
 
-					_gl.texSubImage2D( _gl.TEXTURE_2D, level, dstX, dstY, width, height, glFormat, glType, image );
+					if ( srcTexture.isCompressedTexture ) {
+
+						_gl.compressedTexSubImage2D( _gl.TEXTURE_2D, level, dstX, dstY, image.width, image.height, glFormat, image.data );
+
+					} else {
+
+						_gl.texSubImage2D( _gl.TEXTURE_2D, level, dstX, dstY, width, height, glFormat, glType, image );
+
+					}
 
 				}
 
@@ -2748,19 +2771,47 @@ class WebGLRenderer {
 			_gl.pixelStorei( _gl.UNPACK_SKIP_ROWS, minY );
 			_gl.pixelStorei( _gl.UNPACK_SKIP_IMAGES, minZ );
 
-			if ( srcTexture.isDataTexture || srcTexture.isData3DTexture ) {
+			if ( srcTexture.isRenderTargetTexture || srcTexture.isDepthTexture ) {
+
+				const srcTextureProperties = properties.get( srcTexture );
+				const dstTextureProperties = properties.get( dstTexture );
+				const srcRenderTargetProperties = properties.get( srcTextureProperties.__renderTarget );
+				const dstRenderTargetProperties = properties.get( dstTextureProperties.__renderTarget );
+
+				state.bindFramebuffer( _gl.READ_FRAMEBUFFER, srcRenderTargetProperties.__webglFramebuffer );
 
-				_gl.texSubImage3D( glTarget, level, dstX, dstY, dstZ, width, height, depth, glFormat, glType, image.data );
+				_gl.framebufferTextureLayer( _gl.READ_FRAMEBUFFER, _gl.COLOR_ATTACHMENT0, properties.get( srcTexture ).__webglTexture, level, 0 );
+
+				state.bindFramebuffer( _gl.DRAW_FRAMEBUFFER, dstRenderTargetProperties.__webglFramebuffer );
+
+				_gl.framebufferTextureLayer( _gl.DRAW_FRAMEBUFFER, _gl.COLOR_ATTACHMENT0, properties.get( dstTexture ).__webglTexture, level, 0 );
+
+				let mask = _gl.COLOR_BUFFER_BIT;
+
+				if ( srcTexture.isDepthTexture ) mask = _gl.DEPTH_BUFFER_BIT;
+
+				_gl.blitFramebuffer( minX, minY, width, height, dstX, dstY, width, height, mask, _gl.NEAREST );
+
+				state.bindFramebuffer( _gl.READ_FRAMEBUFFER, null );
+				state.bindFramebuffer( _gl.DRAW_FRAMEBUFFER, null );
 
 			} else {
 
-				if ( dstTexture.isCompressedArrayTexture ) {
+				if ( srcTexture.isDataTexture || srcTexture.isData3DTexture ) {
 
-					_gl.compressedTexSubImage3D( glTarget, level, dstX, dstY, dstZ, width, height, depth, glFormat, image.data );
+					_gl.texSubImage3D( glTarget, level, dstX, dstY, dstZ, width, height, depth, glFormat, glType, image.data );
 
 				} else {
 
-					_gl.texSubImage3D( glTarget, level, dstX, dstY, dstZ, width, height, depth, glFormat, glType, image );
+					if ( dstTexture.isCompressedArrayTexture ) {
+
+						_gl.compressedTexSubImage3D( glTarget, level, dstX, dstY, dstZ, width, height, depth, glFormat, image.data );
+
+					} else {
+
+						_gl.texSubImage3D( glTarget, level, dstX, dstY, dstZ, width, height, depth, glFormat, glType, image );
+
+					}
 
 				}
 

src/renderers/webgl/WebGLTextures.js

@@ -1417,6 +1417,9 @@ function WebGLTextures( _gl, extensions, state, properties, capabilities, utils,
 		const glType = utils.convert( texture.type );
 		const glInternalFormat = getInternalFormat( texture.internalFormat, glFormat, glType, texture.colorSpace );
 		const renderTargetProperties = properties.get( renderTarget );
+		const textureProperties = properties.get( texture );
+
+		textureProperties.__renderTarget = renderTarget;
 
 		if ( ! renderTargetProperties.__hasExternalTextures ) {
 
@@ -1439,11 +1442,11 @@ function WebGLTextures( _gl, extensions, state, properties, capabilities, utils,
 
 		if ( useMultisampledRTT( renderTarget ) ) {
 
-			multisampledRTTExt.framebufferTexture2DMultisampleEXT( _gl.FRAMEBUFFER, attachment, textureTarget, properties.get( texture ).__webglTexture, 0, getRenderTargetSamples( renderTarget ) );
+			multisampledRTTExt.framebufferTexture2DMultisampleEXT( _gl.FRAMEBUFFER, attachment, textureTarget, textureProperties.__webglTexture, 0, getRenderTargetSamples( renderTarget ) );
 
 		} else if ( textureTarget === _gl.TEXTURE_2D || ( textureTarget >= _gl.TEXTURE_CUBE_MAP_POSITIVE_X && textureTarget <= _gl.TEXTURE_CUBE_MAP_NEGATIVE_Z ) ) { // see #24753
 
-			_gl.framebufferTexture2D( _gl.FRAMEBUFFER, attachment, textureTarget, properties.get( texture ).__webglTexture, level );
+			_gl.framebufferTexture2D( _gl.FRAMEBUFFER, attachment, textureTarget, textureProperties.__webglTexture, level );
 
 		}
 
@@ -1532,8 +1535,11 @@ function WebGLTextures( _gl, extensions, state, properties, capabilities, utils,
 
 		}
 
+		const textureProperties = properties.get( renderTarget.depthTexture );
+		textureProperties.__renderTarget = renderTarget;
+
 		// upload an empty depth texture with framebuffer size
-		if ( ! properties.get( renderTarget.depthTexture ).__webglTexture ||
+		if ( ! textureProperties.__webglTexture ||
 				renderTarget.depthTexture.image.width !== renderTarget.width ||
 				renderTarget.depthTexture.image.height !== renderTarget.height ) {
 
@@ -1545,7 +1551,7 @@ function WebGLTextures( _gl, extensions, state, properties, capabilities, utils,
 
 		setTexture2D( renderTarget.depthTexture, 0 );
 
-		const webglDepthTexture = properties.get( renderTarget.depthTexture ).__webglTexture;
+		const webglDepthTexture = textureProperties.__webglTexture;
 		const samples = getRenderTargetSamples( renderTarget );
 
 		if ( renderTarget.depthTexture.format === DepthFormat ) {