shader_type canvas_item;

// source: https://godotshaders.com/shader/smooth-2d-cloud/
// inspired by: https://www.youtube.com/watch?v=8OrvIQUFptA&t=2s
uniform sampler2D perlin_noise: repeat_enable;
uniform sampler2D cell_noise: repeat_enable;

//#define pow2(x) (x * x)
////#define iResolution 1.0/SCREEN_PIXEL_SIZE

//const int samples = 16;
//const int half_samples = 8;
//const float sigma = float(samples) * 0.25;

//float gaussian(vec2 i) {
	//return 1.0 / (2.0 * PI * pow2(sigma)) * exp(-((pow2(i.x) + pow2(i.y)) / (2.0 * pow2(sigma))));
//}
//
//float blur(sampler2D sp, vec2 uv, vec2 scale) {
	//float col = 0.0;
	//float accum = 0.0;
	//float weight = 1.0;
	//vec2 offset;
	//for (int x = - half_samples ; x < half_samples; ++x) {
		//for (int y = - half_samples; y < half_samples; ++y) {
			//offset = vec2(float(x), float(y));
			////weight = gaussian(offset);
			//col += texture(sp, uv + scale * offset).r * weight;
			//accum += weight;
		//}
	//}
	//return col / accum;
//}

void fragment() {
	vec2 uv1 = vec2(UV.x + TIME * .02, UV.y + TIME * .005);
	vec2 uv2 = vec2(UV.x + TIME * .03, UV.y + TIME * .005);

	//float noise1 = blur(perlin_noise, uv1, SCREEN_PIXEL_SIZE);
	//float noise2 = blur(cell_noise, uv2, SCREEN_PIXEL_SIZE);
	float noise1 = texture(perlin_noise, uv1).r;
	float noise2 = texture(cell_noise, uv2).r;
	//noise1 = 1.0;
	//noise2 = 1.0;
	float noise = smoothstep(noise1 * noise2, .0, .15);

	COLOR.a *= noise;
}