t-karcher

shader_type canvas_item;

uniform sampler2D screen_texture : hint_screen_texture, filter_nearest;
uniform float radius = 3.0;

void fragment() {
	vec2 uv = SCREEN_UV;
	uv.y = 1.0 - uv.y; // seems like the origin changed in Godot 4.
	vec2 surface = vec2(0.5, 0.2);
	vec2 center = surface - vec2(0, radius);

Brickcaster

--[[
    Implemented as described here:
    http://flafla2.github.io/2014/08/09/perlinnoise.html
]]--

perlin = {}
perlin.p = {}

-- Hash lookup table as defined by Ken Perlin
-- This is a randomly arranged array of all numbers from 0-255 inclusive