How to get a normal of region or region_3d?

I’m really sorry. because a lot of my questions.

Perhaps, Is there method that get a normal of region or region_3d?

Please answer to me.
Thank you.

what kind of vector would that be?

The forward direction of the virtual camera?

I want to a normal vector of region as 3D View Port Direction. == Orbit Direction.

Look at below image.

Please answer to me.

Its not clear what you want, and your attachement doesnt work for me.

What do you mean by normal of a 3D view? The camera world space forward direction? What do you mean by orbit direction? That only makes sense as the camera’s displacement vector over time. It doesn’t make sense as a static value.

To explain further :

I want to get a Screen direction.