How do I check if object's position projects to ScreenSpace "behind" the camera?

Unity Engine
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1

I there a cheaper way to do it every frame outside of [GeometryUtility.CalculateFrustumPlanes](http://unity3d.com/support/documentation/ScriptReference/GeometryUtility.CalculateFrustumPlanes.html) and [GeometryUtility.TestPlanesAABB](http://unity3d.com/support/documentation/ScriptReference/GeometryUtility.TestPlanesAABB.html)?

2

Dot product of Camera forward vector (+Z) and vector from camera position to object:

  • positive: in front of camera viewplane (may be well outside of frustum though!)

  • negative: behind camera viewplane

result = Vector3.Dot( camera.transform.forward, target.position - camera.transform.position);
3

Ah, that makes sense. I suppose as long as it is not behind the camera, the projection to screen simply return coordinates outside of viewport space when projected object is outside of frustum.