USDZExporter: Add camera support.

[Vochsel]

Description

Adding support for perspective and orthographic cameras added to the scene to be exported.

Discussion

This requires the camera to be explicitly added to the scene to be picked up, useful when there are multiple cameras, but potentially confusing for basic examples, as adding a camera to the scene is not common Three.js practice. Happy to discuss if there is a better way to allow this.

[Mugen87]

The change seems to work. I can see the exported camera in XCode:

[Mugen87]

This requires the camera to be explicitly added to the scene to be picked up, useful when there are multiple cameras, but potentially confusing for basic examples, as adding a camera to the scene is not common Three.js practice.

GLTFExporter works similar, see:

three.js/examples/misc_exporter_gltf.html

Lines 155 to 159 in a10999a

	camera = new THREE.PerspectiveCamera( 45, window.innerWidth / window.innerHeight, 1, 2000 );
	camera.position.set( 600, 400, 0 );
	camera.name = 'PerspectiveCamera';
	scene1.add( camera );

[Vochsel]

Ah cool, thanks for the context and help on my first ThreeJS PR! @Mugen87