About the orbitView.setZoom()

[lembas]

Thank you Pat. I drew and understood it. The earth is not flat so the vertical under the eye and the vertical at the center point are not parallel. And as I see on my drawing it is a little bit hard to find the equation just using the polar coordinates. we have to use the Vec4 class. It may be a future work for me.

For the second case, as you say I cannot use view.computePositionFromScreenPoint. What should I use to take the terrain into account?

[patmurris]

There are different ways to get a point on the terrain surface. You will find a computeSurfacePoint() method in a couple places in the SDK. The strategy is to try first the terrain geometry and then fall back onto elevation data.

0.6 does include a terrain/line intersection code that should help here. There is also the ray casting support which uses elevation data. Have a look inside the BasicDragger util class used in several examples.

Edit: thinking again about the zoom 'adjustment' formula i proposed in my previous post, i'm wondering whether it is correct... You should figure it out from the drawing though

[lembas]

After many questions here is a little contribution for the community

	private Position getTerrainPositionFromScreenPoint(WorldWindowGLCanvas wwCanvas, int screenX, int screenY) {
		View view = wwCanvas.getView();
		Line ray = view.computeRayFromScreenPoint(screenX, screenY);
		Intersection[] intersections = wwCanvas.getSceneController().getTerrain().intersect(ray);
		Globe globe = wwCanvas.getModel().getGlobe();
		if (intersections != null && intersections.length > 0)
			return globe.computePositionFromPoint(intersections[0].getIntersectionPoint());
		else
			return RayCastingSupport.intersectRayWithTerrain(globe, ray.getOrigin(), ray.getDirection(), 200, 20);
	}

And about your formula, it does not work
If I click on a lower elevation point on earth, my altitude is decreasing.

Looking at the sketch I drew, I can see that it is not easy to fix the altitude by setting zoom on an ellipsoidal earth.

I could not solve how we can change the eye lat/lon and zoom, keeping the eye altitude and the pitch fixed.