Update setupFrameBufferTexture()

src/renderers/webgl/WebGLTextures.js

@@ -637,7 +637,9 @@ function WebGLTextures( _gl, extensions, state, properties, capabilities, utils,
 
 		var glFormat = utils.convert( renderTarget.texture.format );
 		var glType = utils.convert( renderTarget.texture.type );
-		state.texImage2D( textureTarget, 0, glFormat, renderTarget.width, renderTarget.height, 0, glFormat, glType, null );
+		var glInternalFormat = getInternalFormat( glFormat, glType );
+		var array = ( _isWebGL2 ) ? new Uint8Array( renderTarget.width * renderTarget.height * 4 ) : null;
+		state.texImage2D( textureTarget, 0, glInternalFormat, renderTarget.width, renderTarget.height, 0, glFormat, glType, array );
 		_gl.bindFramebuffer( _gl.FRAMEBUFFER, framebuffer );
 		_gl.framebufferTexture2D( _gl.FRAMEBUFFER, attachment, textureTarget, properties.get( renderTarget.texture ).__webglTexture, 0 );
 		_gl.bindFramebuffer( _gl.FRAMEBUFFER, null );