How can I change screen shape?

I want to change the final screen, a bit like post-process, but I want to change the shape of the final screen.

Like procedural mesh, if i have 9 points data(3x3), I could build a procedural mesh.

And I move some points, the material will become irregular shape based on points data.

So if you have these points data(or vertex), how to make the final screen can have the same irregular shape ,like procedural mesh.