WebGLBakground.setClearColor: Do not set alpha to 1 by default

I had a problem with making a transparent render target correctly. Called setClearAlpha(0) and setClearColor(0x000000) on the active rendertarget, but alpha was then returned to 1 because of the method below (in WebGLBackground). Could it be a better idea to use the value that setClearAlpha saved instead of 1? It might break code where users used a wrong setClearAlpha and the overwrote it with setClearColor by mistake (but with the wanted visual result), making some render targets transparent again when updating three.js.

setClearColor: function ( color, alpha ) {

	clearColor.set( color );
	clearAlpha = alpha !== undefined ? alpha : 1;
	setClear( clearColor, clearAlpha );

}

https://github.com/mrdoob/three.js/blob/dev/src/renderers/webgl/WebGLBackground.js#L210

Three.js version

• [x ] Dev
• r120
• …

Browser

• All of them
• Chrome
• Firefox
• Internet Explorer

OS

• All of them
• Windows
• macOS
• Linux
• Android
• iOS

[inear]

Sure! Can put some thoughts into a PR, at least as a discussion starter.

[mrdoob]

You mean doing this, right?

setClearColor: function ( color, alpha ) {

	clearColor.set( color );
	if ( alpha !== undefined ) clearAlpha = alpha;
	setClear( clearColor, clearAlpha );

}