shader_type canvas_item;

uniform vec3 color = vec3(1,1,1);
uniform int OCTAVES = 8;
float rand(vec2 coord){
    return fract(sin(dot(coord, vec2(56,78))*1000.0)* 1000.0);
}
float noise(vec2 coord){
    vec2 i = floor(coord);
    vec2 f = fract(coord);

    float a = rand(i);
    float b = rand(i + vec2(1.0, 0.0));
    float c = rand(i + vec2(0.0, 1.0));
    float d = rand(i + vec2(1.0, 1.0));

    vec2 cubic = f * f * (3.0 - 2.0 * f);

    return mix(a, b, cubic.x) + (c - a) * cubic.y * (1.0 - cubic.x) + (d - b) * cubic.x * cubic.y;
}

float fbm(vec2 coord){  //fractal brownian motion
    float value = 0.0;
    float scale = 0.5;

    for(int i = 0; i < OCTAVES; i++){
        value += noise(coord) * scale;
        coord *= 2.0;
        scale *= 0.5;
    }
    return value;
}

void fragment(){
    vec2 coord = UV * 30.0;

    vec2 motion = vec2(fbm(coord + vec2(TIME * .5 ,TIME * -0.6)));

    float final = fbm(coord + motion);

    COLOR = vec4(color, final * .3);

}