add proper support transparent backgrounds for EffectComposer and BloomPass.

examples/js/postprocessing/BloomPass.js

@@ -11,7 +11,7 @@ THREE.BloomPass = function ( strength, kernelSize, sigma, resolution ) {
 
 	// render targets
 
-	var pars = { minFilter: THREE.LinearFilter, magFilter: THREE.LinearFilter, format: THREE.RGBFormat };
+	var pars = { minFilter: THREE.LinearFilter, magFilter: THREE.LinearFilter, format: THREE.RGBAFormat };
 
 	this.renderTargetX = new THREE.WebGLRenderTarget( resolution, resolution, pars );
 	this.renderTargetY = new THREE.WebGLRenderTarget( resolution, resolution, pars );

examples/js/postprocessing/EffectComposer.js

@@ -12,7 +12,7 @@ THREE.EffectComposer = function ( renderer, renderTarget ) {
 
 		var width  = Math.floor( renderer.context.canvas.width  / pixelRatio ) || 1;
 		var height = Math.floor( renderer.context.canvas.height / pixelRatio ) || 1;
-		var parameters = { minFilter: THREE.LinearFilter, magFilter: THREE.LinearFilter, format: THREE.RGBFormat, stencilBuffer: false };
+		var parameters = { minFilter: THREE.LinearFilter, magFilter: THREE.LinearFilter, format: THREE.RGBAFormat, stencilBuffer: false };
 
 		renderTarget = new THREE.WebGLRenderTarget( width, height, parameters );