Get the minimum radius of a sphere around an Unity3D Camera that guarantees that outside of that radius nothing will intersect the camera's frustum

CameraRadiusUnity.cs

// Get the minimum radius sphere of a camera in which the camera crosses something. For a spherecast, for example.
public static float GetRadiusOfCamera(Camera camera) {
	/*
	Calculate the radius of the smallest sphere that contains perfectly the camera
	The vertices of the sides of the near plane must touch the sphere and the
	and also from the near plane center going backwards by camera.nearClipPlane 

		 SIDE
	   _________
	  /  /|     \
	 / a/ |      \sphere
	/  /  |c      \
	| /   |       |
	|/____|       |
	   b

		 FRONT
	   ________
	  /        \
	 /___fw_____\sphere
	/ |\       | \
	| | \c  ffh| |
	| |  \     | |
		  /|\
		   |
		Center of the near plane frustum

	b => camera.nearClipPlane
	c => sqrt(frustumHeightHalf^2 + frustumWidthHalf^2)
	a => radius = sqrt(b^2 + c^2)
	fw => frustum width
	fhh => frustumHeightHalf = frustum height / 2
	*/

	// http://docs.unity3d.com/Manual/FrustumSizeAtDistance.html
	float b = camera.nearClipPlane;
	float frustumHeightHalf = b * Mathf.Tan(camera.fieldOfView * 0.5f * Mathf.Deg2Rad);
	float frustumWidthHalf = frustumHeightHalf * camera.aspect;
	float c = Mathf.Sqrt(frustumHeightHalf * frustumHeightHalf + frustumWidthHalf * frustumWidthHalf);
	return Mathf.Sqrt(b * b + c * c);
}