godot-demo-projects/2d/sprite_shaders/shaders/fatty.gdshader

shader_type canvas_item;

render_mode blend_mix;
uniform float fattyness = 2.0;

void fragment() {
	vec2 ruv = UV - vec2(0.5, 0.5);
	vec2 dir = normalize(ruv);
	float len = length(ruv);

	len = pow(len * 2.0, fattyness) * 0.5;
	ruv = len * dir;

	vec4 col = texture(TEXTURE, ruv + vec2(0.5, 0.5));

	COLOR = col;
}