shader_type canvas_item;

uniform float speed = 5.0;
uniform float scale = 20.0;
uniform float intensity = 1;
uniform sampler2D noise;

float rand(vec2 coord) {
	return fract(sin(dot(coord, vec2(12.9898, 78.233))) * 43758.5453);
}

float cellular(vec2 coord) {
	vec2 i = floor(coord);
	vec2 f = fract(coord);

	float min_dist = 1.0;

	for (int y = -1; y <= 1; y++) {
		for (int x = -1; x <= 1; x++) {
			vec2 neighbor = vec2(float(x), float(y));
			vec2 point = vec2(rand(i + neighbor), rand(i + neighbor + vec2(1000.0)));
			point = 0.5 * sin(TIME * speed + 6.2831 * point);
			vec2 diff = neighbor + point - f;
			float dist = length(diff);
			min_dist = min(min_dist, dist);
		}
	}

	return min_dist;
}

void fragment() {
	if (COLOR.a != 0.0) {
		vec2 coord = UV * scale;

		float pattern = cellular(coord);

		COLOR = vec4(COLOR.rgb, (pattern > intensity) ? 0.0 : 1.0);
	}
}