uniform vec2 u_resolution;
uniform vec2 u_mouse;
uniform float u_time;
varying float vDistance;
float random(in float x) {
    return fract(sin(x) * 1e4);
}

        // Based on Morgan McGuire @morgan3d
        // https://www.shadertoy.com/view/4dS3Wd
float noise(in vec3 p) {
    const vec3 step = vec3(110.0, 241.0, 171.0);

    vec3 i = floor(p);
    vec3 f = fract(p);

            // For performance, compute the base input to a
            // 1D random from the integer part of the
            // argument and the incremental change to the
            // 1D based on the 3D -> 1D wrapping
    float n = dot(i, step);

    vec3 u = f * f * (3.0 - 2.0 * f);
    return mix(mix(mix(random(n + dot(step, vec3(0, 0, 0))), random(n + dot(step, vec3(1, 0, 0))), u.x), mix(random(n + dot(step, vec3(0, 1, 0))), random(n + dot(step, vec3(1, 1, 0))), u.x), u.y), mix(mix(random(n + dot(step, vec3(0, 0, 1))), random(n + dot(step, vec3(1, 0, 1))), u.x), mix(random(n + dot(step, vec3(0, 1, 1))), random(n + dot(step, vec3(1, 1, 1))), u.x), u.y), u.z);
}