setRenderTarget( renderTarget, activeCubeFace = 0, activeMipmapLevel = 0 ) {

		this._renderTarget = renderTarget;
		this._activeCubeFace = activeCubeFace;
		this._activeMipmapLevel = activeMipmapLevel;

	}
Sets the given render target. Calling this method means the renderer does not
target the default framebuffer (meaning the canvas) anymore but a custom framebuffer.
Use `null` as the first argument to reset the state.

@param {?RenderTarget} renderTarget - The render target to set.
@param {number} [activeCubeFace=0] - The active cube face.
@param {number} [activeMipmapLevel=0] - The active mipmap level.