# Simple Fog effect possible on mobile?

Attention Topic was automatically imported from the old Question2Answer platform.

Hi, I want to add a subtle snow storm effect for my 2d mobile game.
I looks fine for me when using fog shaders and adjusting them a little bit, e.g. this one:

``````shader_type canvas_item;

float rand(vec2 n) {

return fract(cos(dot(n, vec2(1.9898, 2.1414))) * 458.5453);

}

float noise(vec2 n) {

vec2 d = vec2(0.0, 1.0);

vec2 b = floor(n);

vec2 f = smoothstep(vec2(0.0), vec2(1.0), fract(n));

return mix(mix(rand(b), rand(b + d.yx), f.x), mix(rand(b + d.xy), rand(b + d.yy), f.x), f.y);

}

float fbm(vec2 n) {

return noise(n) * 0.5 + noise(n * 0.5) * 0.25 + noise(n * 8.0) * 0.125 + noise(n * 8.0) * 0.065;

}

void fragment(){

vec2 p = vec2(UV.x * 2.5, -UV.y * 1.0);

float r = fbm(p - vec2(0.0, fbm(p) + TIME *0.5));
if (r < 0.3)
{
r = 0.0;
}
else
{
r = 1.42857142857* r - 0.42857142857
}
COLOR = vec4(1.0,1.0,1.0,r);

}
``````

Or the one shown in this tutorial:

Problem is that I need them applied over the whole screen all the time, which causes the performance on my mobile would drop from over 60 to below 30.
I’m not yet into shaders, but I would be willing to learn them for this, but I’m not sure if it’s worthwhile.

Is it possible to achieve something like this on mobile without a huge performance drop?
Maybe by using an integrated noise texture instead of generating the noise inside the shader? Or maybe not using shaders at all, but pre-rendered animations?