Lines follow you everywhere!

LinienVerfolgungFarbe.pde

    void setup() {
      size(500, 500);
    }
    
    int lineLength = 20;
    int interval = 25;
    
    int resolution = 10;
    int blue = 0;
    int border = 300;
    
    void draw() {
      fill(100);
      rect(0, 0, width, height);
      //Colors
      noStroke();  
      for (int i = 0; i < border; i = i + resolution)
      {
        for (int j = 0; j < border; j = j + resolution)
        {
          fill(i, j, blue);
          rect(i, j, i+resolution, j+resolution);
        }
      }
    
      //Lines
      stroke(0);
      for (int i = 0; i <= width; i = i + interval) {
        for (int j = 0; j <= height; j = j + interval) {
          float angle = atan2(mouseY-j, mouseX-i);
          line(i, j, i+lineLength*cos(angle), j+lineLength*sin(angle));
        }
      }
    }