This example is for Processing 3+. If you have a previous version, use the examples included with your software. If you see any errors or have suggestions, please let us know.

Embedding Iteration.

Embedding "for" structures allows repetition in two dimensions. *



size(640, 360); 
background(0); 

int gridSize = 40;

for (int x = gridSize; x <= width - gridSize; x += gridSize) {
  for (int y = gridSize; y <= height - gridSize; y += gridSize) {
    noStroke();
    fill(255);
    rect(x-1, y-1, 3, 3);
    stroke(255, 100);
    line(x, y, width/2, height/2);
  }
}