thirdPersonCameraHelper.cs

using UnityEngine;

public static class thirdPersonCameraHelper
{
    public struct ClipPlanePoints
    {
        public Vector3 upperLeft;
        public Vector3 upperRight;
        public Vector3 lowerLeft;
        public Vector3 lowerRight;
    }

    // Clamp angle to between -360, 360.
    public static float clampingAngle(float angle, float min, float max)
    {
        do
        {
            if (angle < -360)
                angle += 360;
            if (angle > 360)
                angle -= 360;
        } while (angle < -360 || angle > 360);



        return Mathf.Clamp (angle, min, max);
    }

    public static ClipPlanePoints ClipPlaneAtNear (Vector3 pos)
    {
        ClipPlanePoints clipPlanePoints = new ClipPlanePoints ();

        // Ensure there is a main camera for us to check.
        if (!Camera.main)
            return clipPlanePoints;

        // Properties to determine the main camera's near clip plane.
        Transform mainCameraTransform = Camera.main.transform;
        float halfFieldOfView = (Camera.main.fieldOfView / 2) * Mathf.Deg2Rad;
        float aspect = Camera.main.aspect;
        float distance = Camera.main.nearClipPlane;
        float height = distance * Mathf.Tan (halfFieldOfView);
        float width = height * aspect;

        clipPlanePoints.lowerRight = pos + mainCameraTransform.right * width;
        clipPlanePoints.lowerRight -= mainCameraTransform.up * height;
        clipPlanePoints.lowerRight += mainCameraTransform.forward * distance;

        clipPlanePoints.lowerLeft = pos - mainCameraTransform.right * width;
        clipPlanePoints.lowerLeft -= mainCameraTransform.up * height;
        clipPlanePoints.lowerLeft += mainCameraTransform.forward * distance;

        clipPlanePoints.upperRight = pos + mainCameraTransform.right * width;
        clipPlanePoints.upperRight += mainCameraTransform.up * height;
        clipPlanePoints.upperRight += mainCameraTransform.forward * distance;

        clipPlanePoints.upperLeft = pos - mainCameraTransform.right * width;
        clipPlanePoints.upperLeft += mainCameraTransform.up * height;
        clipPlanePoints.upperLeft += mainCameraTransform.forward * distance;

        return clipPlanePoints;
    }
}