setColorMask( colorMask ) {

		if ( this.currentColorMask !== colorMask ) {

			this.gl.colorMask( colorMask, colorMask, colorMask, colorMask );
			this.currentColorMask = colorMask;

		}

	}
Specifies whether colors can be written when rendering
into a framebuffer or not.

This method caches the state so `gl.colorMask()` is only
called when necessary.

@param {boolean} colorMask - The color mask.