Merge pull request #5907 from kurzemnieks/readPixels

added new function readRenderTargetPixels to WebGLRenderer

examples/webgl_interactive_cubes_gpu.html

@@ -203,12 +203,11 @@
 
 				renderer.render( pickingScene, camera, pickingTexture );
 
-				var gl = self.renderer.getContext();
+				//create buffer for reading single pixel
+				var pixelBuffer = new Uint8Array( 4 );
 
 				//read the pixel under the mouse from the texture
-
-				var pixelBuffer = new Uint8Array( 4 );
-				gl.readPixels( mouse.x, pickingTexture.height - mouse.y, 1, 1, gl.RGBA, gl.UNSIGNED_BYTE, pixelBuffer );
+				renderer.readRenderTargetPixels(pickingTexture, mouse.x, pickingTexture.height - mouse.y, 1, 1, pixelBuffer);
 
 				//interpret the pixel as an ID
 

src/renderers/WebGLRenderer.js

@@ -6185,6 +6185,54 @@ THREE.WebGLRenderer = function ( parameters ) {
 
 	};
 
+	this.readRenderTargetPixels = function( renderTarget, x, y, width, height, buffer ) {
+
+	    if ( ! ( renderTarget instanceof THREE.WebGLRenderTarget ) ) {
+
+	        console.error( 'THREE.WebGLRenderer.readRenderTargetPixels: renderTarget is not THREE.WebGLRenderTarget.' );
+	        return;
+
+	    }
+
+	    if ( renderTarget.__webglFramebuffer ) {
+
+	        if ( renderTarget.format !== THREE.RGBAFormat ) {
+
+	            console.error( 'THREE.WebGLRenderer.readRenderTargetPixels: renderTarget is not in RGBA format. readPixels can read only RGBA format.' );
+	            return;
+
+	        }
+
+	        var restore = false;
+
+	        if ( renderTarget.__webglFramebuffer !== _currentFramebuffer ) {
+
+	            _gl.bindFramebuffer( _gl.FRAMEBUFFER, renderTarget.__webglFramebuffer );
+
+	            restore = true;
+
+	        }
+
+	        if ( _gl.checkFramebufferStatus( _gl.FRAMEBUFFER ) === _gl.FRAMEBUFFER_COMPLETE ) {
+
+	            _gl.readPixels( x, y, width, height, _gl.RGBA, _gl.UNSIGNED_BYTE, buffer );
+
+	        } else {
+
+	            console.error( 'THREE.WebGLRenderer.readRenderTargetPixels: readPixels from renderTarget failed. Framebuffer not complete.' );
+
+	        }
+
+	        if ( restore ) {
+
+	            _gl.bindFramebuffer( _gl.FRAMEBUFFER, _currentFramebuffer );
+
+	        }
+
+	    }
+
+	};
+
 	function updateRenderTargetMipmap ( renderTarget ) {
 
 		if ( renderTarget instanceof THREE.WebGLRenderTargetCube ) {