shader_type spatial;

uniform float scale : hint_range(0.1, 2.0, 0.1) = 1.0;
uniform float speed : hint_range(0.1, 2.0, 0.1) = 0.2;
uniform float strenght : hint_range(10., 500., 10.) = 100.;
uniform sampler2D color_ramp;
varying vec3 world_position;

vec2 random(vec2 uv) {
	return vec2(fract(sin(dot(uv.xy,
		vec2(12.9898,78.233))) * 43758.5453123));
}

float worley(vec2 uv, float columns, float rows) {
	
	vec2 index_uv = floor(vec2(uv.x * columns, uv.y * rows));
	vec2 fract_uv = fract(vec2(uv.x * columns, uv.y * rows));
	
	float minimum_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 = random(index_uv + neighbor);
			
			vec2 diff = neighbor + point - fract_uv;
			float dist = length(diff);
			minimum_dist = min(minimum_dist, dist);
		}
	}
	
	return minimum_dist;
}

void vertex(){
    world_position = (MODEL_MATRIX * vec4(VERTEX, 1.0)).xyz;
}

void fragment(){
    float worley_value = worley(world_position.xz * scale + TIME * speed, 3.0, 3.0);
    float worley_value_2 = worley(world_position.xz * scale * 2. - TIME * speed, 3.0, 3.0);
    
    float color = texture(color_ramp, vec2(worley_value*worley_value_2)).r;
    color = min(0.99, color);
    color = log(0.999)/log(color);
    color *= strenght;
    ALPHA = color;
    EMISSION = vec3(color);
}