```
/////////////////////////////////
// 2D Radial Distortion Shader //
/////////////////////////////////
// Screen space shader for Godot, based on: https://gist.github.com/aggregate1166877/a889083801d67917c26c12a98e7f57a7
shader_type canvas_item;
uniform float aspect = 1.0;
uniform float distortion = 1.0;
uniform float radius = 1.0;
uniform float alpha = 1.0;
uniform float crop = 1.0;
uniform vec4 crop_color : hint_color = vec4(0,0,0,1);
vec2 distort(vec2 p)
{
float d = length(p);
float z = sqrt(distortion + d * d * -distortion);
float r = atan(d, z) / 3.1415926535;
float phi = atan(p.y, p.x);
return vec2(r * cos(phi) * (1.0 / aspect) + 0.5, r * sin(phi) + 0.5);
}
void fragment()
{
vec2 xy = (SCREEN_UV * 2.0 - 1.0); // move origin of UV coordinates to center of screen
xy = vec2(xy.x * aspect, xy.y); // adjust aspect ratio
float d = length(xy); // distance from center
vec4 tex;
if (d < radius)
{
xy = distort(xy);
tex = texture(SCREEN_TEXTURE, xy);
COLOR = tex;
COLOR.a = alpha;
}
// radial crop
if (d > crop)
{
COLOR = crop_color;
}
}
```