Question Cube map as post process

Hey folks, I’m playing around with a screen noise post process. It’s pretty simple, just an unlit shader graph with noise texture set to multiply with the screen (stole a blit render feature from a tutorial).

Because it’s a simple texture overlay, the noise looks fine when the camera is still, but when you rotate the camera, the illusion breaks. It’s really apparent that the scene rotates in relation to the viewer, but the noise does not.

I thought sampling noise from a cube map might work, since it’s a 3d texture, and as the view rotates, the noise might remain in place. BUT, I cannot figure out how to sample a cube map that isn’t on a 3d object. Is this possible? Am I barking up the wrong tree?

Any wisdom here would be appreciated. Thanks!

 

Looking to add noise/age like this: