Unity3D 中的FOV

一直以為Unity中的相機FOV指的是frustum兩個對角邊的方向夾角，所以在看一篇教程的時候怎么算都算不對。后來靈機一動，查了一下，才發現Unity中的Fov指的是垂直方向的FOV：

參見這里：https://docs.unity3d.com/ScriptReference/Camera-fieldOfView.html

This is the vertical field of view; horizontal FOV varies depending on the viewport's aspect ratio. 

　　圖示如下：

圖片來源：http://rungame.me/blog/2014/05/12/u3d-projection/

附上我看的教程的部分代碼，用於計算frustum的四個邊：

private Matrix4x4 GetFrustumCorners(Camera cam)
    {
        float camFov = cam.fieldOfView;
        float camAspect = cam.aspect;

        Matrix4x4 frustumCorners = Matrix4x4.identity;

        float fovWHalf = camFov * 0.5f;

        float tan_fov = Mathf.Tan(fovWHalf * Mathf.Deg2Rad);

        Vector3 toTop = Vector3.up * tan_fov;
        Vector3 toRight = Vector3.right * tan_fov * camAspect;


        Vector3 topLeft = (-Vector3.forward - toRight + toTop);
        Vector3 topRight = (-Vector3.forward + toRight + toTop);
        Vector3 bottomRight = (-Vector3.forward + toRight - toTop);
        Vector3 bottomLeft = (-Vector3.forward - toRight - toTop);

        frustumCorners.SetRow(0, topLeft);
        frustumCorners.SetRow(1, topRight);
        frustumCorners.SetRow(2, bottomRight);
        frustumCorners.SetRow(3, bottomLeft);

        return frustumCorners;
    }