education-apps/kellett_screen_starter/fog.gdshader

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shader_type canvas_item;
uniform vec3 color = vec3(0.65, 0.86, 0.95);
uniform int OCTAVES = 8;
float rand(vec2 coord){
return fract(sin(dot(coord, vec2(56, 78)) * 4000.0) * 1000.0);
}
float noise(vec2 coord){
vec2 i = floor(coord);
vec2 f = fract(coord);
// 4 corners of a rectangle surrounding our point
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){
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 * 2.0;
vec2 motion = vec2( fbm(coord + vec2(TIME * -0.3, TIME * 0.2)) );
float final = fbm(coord + motion);
COLOR = vec4(color, final * 0.8);
}