Plane equation with polygon game object normal only

Unity Engine
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1

I am trying to check when the player camera is in front or behind a portal polygon using the normal only and not the direction the game object is pointed toward.

I want to only use the normal of the polygon game object to know when the player crosses a portal polygon.

I can’t use the direction x, y, and z.

How do I only use the plane equation with polygon game object normal to check if the player is in front or behind it or at zero to the game object?

2

If you have a Plane you can check which side of the plane a point is on using this function:

You can create the Plane using the normal and any point on the plane: