Getting the vector directions that correspond to the direction of the frustum planes

TL;DR: Hi all! I have been struggling with the following task: how can I find out the vector directions that correspond to each of the perspective camera view frustum planes?

A bit more detail:
So, if Camera.main.transform.forward is the forward direction of the camera, let's call the 4 planes going out from the camera as the top, down, left and right planes (in relation to the current orientation of the camera). I need to shoot rays along the planes and for that, I plan to use:

Camera.main.transform;position + plane_direction * given_length

But I don't know how to find the "plane_direction" that corresponds, for instance, to the direction that the top plane forms from the camera position.

Can anyone help me on that?

 

You can get them with Camera.ViewportPointToRay.
Geting the rays at the middle of the screen edges gives you a ray (point + direction) along the frustum planes.

 

Thanks for your reply! So, I see what you what you are suggesting. I didn't know that ViewportToRay cast rays automatically in those directions. I thought it did it to the forward direction of the camera.

I will give it a try this afternoon.

 

The intended goal of ViewportPointToRay is to point at 3D objects existing at the scene based on a 2D position on the screen (a typical usage is point & click objects in the scene). The side effect is that the edges of the screen represent the exact frustum planes