// Based on https://godotshaders.com/shader/screen-smoke-fog/
shader_type canvas_item;
render_mode blend_mul;

// Stuff related to camera position and offsets
uniform vec2 camera_position;
uniform vec2 camera_zoom = vec2(1.0);
uniform vec2 viewport_size = vec2(1920.0, 1080.0);

// Uniforms for customization
uniform sampler2D noise_texture : repeat_enable;
uniform float cloud_speed : hint_range(0.0, 10.0) 	= 1.0;
uniform float cloud_delay : hint_range(0.0, 100.0) 	= 1.0;
uniform vec2 cloud_dir = vec2(1.0,+1.0);
uniform vec3 cloud_color : source_color = vec3(0.8);
uniform float cloud_alpha : hint_range(0.0, 1.0) = 1.0;
uniform float cloud_size : hint_range(1.0, 100.0) = 10.0;
uniform float cloud_distorsion_speed : hint_range(0.0, 1.) = 0.05;
uniform float density : hint_range(0.0, 1.0) 	= 1.0;
uniform float blur_amount : hint_range(0.0, 1.0) 	= 1.0;

void fragment() {
	vec2 world_pos = (UV - 0.5) * (viewport_size) / camera_zoom + camera_position;

    //COLOR=texture(noise_texture, world_pos * (1./(cloud_size*100.)));
    
    float time = TIME+cloud_delay;

	vec2 time_offset = time * cloud_dir * cloud_speed * 0.01;
	vec2 distorsion_time_offset = time * cloud_dir * (cloud_speed + vec2(cloud_distorsion_speed,cloud_distorsion_speed)) * 0.01;
    
	vec2 cloud_uv = world_pos * (1./(cloud_size*100.)) + time_offset;
    vec2 distorsion_cloud_uv = world_pos * (1./(cloud_size*100.)) + distorsion_time_offset;
    
	float final_noise = (
        texture(noise_texture, cloud_uv) * 0.5 +
        texture(noise_texture, distorsion_cloud_uv) * 0.5
    ).r;
    
    float edge = smoothstep(density - blur_amount * 0.5, density + blur_amount * 0.5, final_noise);
    
    COLOR = vec4(mix(cloud_color, vec3(1.0), edge), 1.0);
    
    //if (final_noise < density) {
        //COLOR = vec4(cloud_color.r,cloud_color.g,cloud_color.b,1.);
    //} else
        //COLOR = vec4(1.,1.,1.,1.);
}