I'm working with a mapping application (worldwind) and trying to determine the minimum and maximum latitudes and longitudes that are currently displayed. I have access to the frustum, but I'm not sure how to account for the fact that the globe can have its heading and/or pitch changed. Any help on this problem would be appreciated.
thanks,
Jeff
Actually the Frustum isn't the most useful thing in this context. What you need to do is reverse the ModelView-Project transform.
If you can retrieve your projection (frustum) and model-view matrices, then you can invert them. If you project a ray from your camera position along projection space, then you can use those inversions to find that ray in world space. From there, you can intersect that ray with your world to find the exact point where that ray hits the globe.
Do this for the four corners of the screen and then calculate your 2D bounding box based upon those intersection coordinates.