Let it snow!!!
From shadertoy to Godot shader. It works for GLES2 and Android devices!
Shader code
shader_type canvas_item;
uniform float width : hint_range(0.0, 1.0) = 0.5;
uniform float speed : hint_range(0.0, 10.0) = 0.5;
uniform int num_of_layers = 5;
void fragment() {
mat3 p = mat3(vec3(13.323122,23.5112,21.71123), vec3(21.1212,28.7312,11.9312), vec3(21.8112,14.7212,61.3934));
vec2 uv = SCREEN_UV;
vec3 acc = vec3(0.1);
float dof = 5.0 * sin(TIME * 0.1);
for (int i = 0; i < num_of_layers; i++) {
float fi = float(i);
vec2 q = uv * (1.0 + fi * 0.5);
q += vec2(q.y * (width * mod(fi * 7.238917, 1.0) - width * 0.5), speed * TIME / (1.0 + fi * 0.5 * 0.03));
vec3 n = vec3(floor(q), 31.189 + fi);
vec3 m = floor(n) * 0.00001 + fract(n);
vec3 mp = (31415.9 + m) / fract(p * m);
vec3 r = fract(mp);
vec2 s = abs(mod(q, 1.0) - 0.5 + 0.9 * r.xy - 0.45);
s += 0.01 * abs(2.0 * fract(10.0 * q.yx) - 1.0);
float d = 0.6 * max(s.x - s.y, s.x + s.y) + max(s.x, s.y) - 0.01;
float edge = 0.005 + 0.05 * min(0.5 * abs(fi - 5.0 - dof), 1.0);
acc += vec3(smoothstep(edge, -edge, d) * (r.x / (1.0 + 0.02 * fi * 0.5)));
}
COLOR = vec4(vec3(acc), 1.0);
}
