uniform sampler2D u_tex;
uniform float u_time;

varying vec2 v_uv;

float rand(vec2 co){
    return fract(sin(dot(co.xy ,vec2(12.9898,78.233))) * 43758.5453);
}

void main() {",
    float r = 0.0, g = 0.0, b = 0.0;
    vec2 uv = v_uv;
    float position = 0.5 + sin(u_time) * 0.2;

    float n = 0.0;
    vec2 offset = vec2(0.0);

    float dy = (0.5 - abs(uv.y - position)) * 2.0;
    offset.x = 0.2 * dy * dy * dy * sin(uv.y * 10.0 + u_time/3.0);
    uv += offset;
    n = dy * rand(u_time * uv * 6400.0);
    if (n > 0.9) n = 1.0;
    else n = 0.0;

    vec3 c = texture2D(u_tex, uv).rgb;

    r = texture2D(u_tex, uv - offset/10.0).r;
    g = c.g;
    b = texture2D(u_tex, uv + offset/10.0).b;

    gl_FragColor = vec4(r, g, b, 1.0) + vec4(n, n, n, 1.0);
}