1 | dot's-path

int step = 30;
float x, y;

void setup() {
    size(1280, 747);
    background(0);
    fill(255);     //fill(0, 80);
    noStroke();
    y = x = width/2;
}

void draw() {
    circle(x, y, 5);
    x += random(-step, step);
    y += random(-step, step);
    //println (x, '\t', y);
    if (x < 0)
        x = 0;
    if (y < 0)
        y = 0;
    if (x > width)
        x = width;
    if (y > height)
        y = height;
}