fog.shader

shader_type canvas_item;

uniform vec3 color = vec3(0.35, 0.48, 0.95);
uniform int OCTAVES = 4;

float randi(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 = randi(i); 
	float b = randi(i + vec2(1.0, 0.0)); 
	float c = randi(i + vec2(0.0, 1.0)); 
	float d = randi(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){ 
	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 * 20.0; 
	vec2 motion = vec2(fbm(coord + vec2(TIME * -0.5, TIME * 0.5))); 
	float final = fbm(coord + motion);
	
	COLOR = vec4(color, final * 0.5); 
}