function getTargetPixelRatio() {

		return _currentRenderTarget === null ? _pixelRatio : 1;

	}
@author supereggbert / http://www.paulbrunt.co.uk/
@author mrdoob / http://mrdoob.com/
@author alteredq / http://alteredqualia.com/
@author szimek / https://github.com/szimek/
@author tschw