Why do we need to copy the webgl camera?

[trusktr]

threex.htmlmixer/threex.htmlmixer.js

Lines 36 to 48 in 43fdd57

	//////////////////////////////////////////////////////////////////////////////////
	// Handle Camera
	//////////////////////////////////////////////////////////////////////////////////
	var cssCamera = new THREE.PerspectiveCamera(camera.fov, camera.aspect, camera.near*cssFactor, camera.far*cssFactor);
	updateFcts.push(function(){
	cssCamera.quaternion.copy(camera.quaternion)
	cssCamera.position
	.copy(camera.position)
	.multiplyScalar(cssFactor)
	})

?