title: How can I translate the mouse coordinates to 3D coordinates, with a overhead camera, in XNA 4.0?
body: <p>So I am making a game in XNA 4.0 and I am having an issue with translating the coordinates from the mouse to the 3D world. I have used the Viewport.Unproject() method, and it almost works. The issue is that my projection is a "field of view" so the distance away from the center axises is exponential. If I change the projection to be a standard perspective than my 3D objects are deformed. Is there a mathematical fix for using the field of view with the translated data from the mouse coordinates? </p>
  
  <p>I am currently doing some trig. to calculate the width and height of the far plane, based on the camera position, the width &amp; height of the viewport, and the fieldOfView angle. Is there a better method? This is almost dead on.</p>