uniform highp float pixel = 1.0;
uniform highp vec2 red_offset = vec2(0.0, 0.0);
uniform highp vec2 green_offset = vec2(0.0, 0.0);
uniform highp vec2 blue_offset = vec2(0.0, 0.0);
uniform highp float alpha = 1.0;
uniform highp float rand_strength = 1.0;

uniform highp vec4 affected = vec4(0.0, 0.0, 1.0, 1.0);

highp float Hash21(highp vec2 p) {
    p = fract(p*vec2(123.34, 456.21));
    p += dot(p, p+45.32);

    return fract(p.x*p.y);
}

highp vec2 pixelize(highp vec2 uv) {
    highp float mult = 5000.0 / (pixel * pixel);
    uv.x = floor(uv.x * mult) / mult;
    uv.y = floor(uv.y * mult) / mult;
    return uv;
}

highp vec4 chroma(highp vec2 uv, sampler2D tex) {
    highp vec4 col = texture(tex, uv);
    if (abs(red_offset.x) + abs(red_offset.y) > 0.001) {
        col.r = texture(tex, vec2(uv.x + red_offset.x, uv.y + red_offset.y)).r;
    }
    if (abs(green_offset.x) + abs(green_offset.y) > 0.001) {
        col.g = texture(tex, vec2(uv.x + green_offset.x, uv.y + green_offset.y)).g;
    }
    if (abs(blue_offset.x) + abs(blue_offset.y) > 0.001) {
        col.b = texture(tex, vec2(uv.x + blue_offset.x, uv.y + blue_offset.y)).b;
    }

    return col;
}

void fragment() {
    highp vec2 normal_uv = UV;
    highp vec4 normal_col = texture(TEXTURE, UV);
    if (normal_uv.x < affected.x || normal_uv.y < affected.y || normal_uv.x > affected.x + affected.z || normal_uv.y > affected.y + affected.a) {
        COLOR = normal_col;
    }
    else {
        highp vec2 uv = pixelize(UV);
        highp vec4 col = chroma(uv, TEXTURE);
        col.a = col.a * alpha;
        highp vec2 id = floor(uv * 10.0);
        highp float alpha_rand = Hash21(id + floor(TIME*10.0));
        col = col * ( alpha_rand + (rand_strength * (1.0-alpha_rand)) );
        COLOR = col;
    }
}