Shader Vignette Godot 4 (ColorRect)

Shader Vignette  Godot 4 (ColorRect)

shader_type canvas_item;

uniform float alpha = 1.0;
uniform float inner_radius = 0.0;
uniform float outer_radius = 1.0;

void fragment() {
    float x = abs(UV.r-.5)*2.0;
    float y = abs(UV.g-.5)*2.0;
    float q = 1.0-(1.0-sqrt(x*x+y*y)/outer_radius)/(1.0-inner_radius);
    COLOR = vec4(0, 0, 0, q*alpha);
}