Fix spherical light probes always starting at 0,0,0

[grizeldi]

When setting the type of a light probe to spherical, previously the center of the area wasn't set to the probe's position.

The code is untested, as I can't currently build the engine locally, so someone testing it would be welcome. The changes are minimal though, so chances of something breaking are small.

[riccardobl]

If someone wants to test this quickly, without rebuilding the engine locally, it is always possible to download the maven artifacts for every commit from the actions artifacts, in this case from: https://github.com/jMonkeyEngine/jmonkeyengine/actions/runs/396272941

[grizeldi]

Tested it using the following code and it seems to be working. The printed position stays the same.

public class Main extends SimpleApplication {
	private LightProbe probe;

	@Override
	public void simpleInitApp() {
		EnvironmentCamera envCam = new EnvironmentCamera(); //Make an env camera
		stateManager.attach(envCam);
		envCam.initialize(stateManager, this); //Manually initilaize so we can add a probe before the next update happens
		probe = LightProbeFactory.makeProbe(envCam, rootNode);
		probe.getArea().setRadius(10); //Set the probe's radius in world units
		probe.setPosition(new Vector3f(1, 0, -2)); //Position it in 3d space
		rootNode.addLight(probe);
	}

	@Override
	public void simpleUpdate(float tpf) {
		System.out.println("Probe position: " + probe.getPosition());
		switch (probe.getAreaType()){
			case Spherical:
				probe.setAreaType(LightProbe.AreaType.OrientedBox);
				break;
			case OrientedBox:
				probe.setAreaType(LightProbe.AreaType.Spherical);
				break;
		}
	}

	public static void main(String [] args){
		new Main().start();
	}
}