Spork Editor

/*
Clip Grid Example
This example will draw two grids. 
One grid is a grid of black circles.
The other grid is a grid of squares clipped into
a circle.
*/

function setup(){
  /*
  Since this example is just demonstrating a grid,
  we do not need to do any special setup.
  */
}
function draw(){
  
  //variables for grid placement
  var x,y;
  
  //make the background white
  fillcolor('white');
  rect(0,0,width,height);
  fill();
  
  //change fill color back to black for circles
  fillcolor('black');
  
  //x will take on values 20, 60, 100...
  for (x=20;x<width;x=x+40)
    //for each value of x, y takes on 20, 60...
    for (y=20;y<height;y=y+40){
      circle(x,y,10);
      fill();
    }
  
  //draw circle for clipping
  color(0,0,0,0);	//transparent boundary
  fillcolor('white')	//white background
  circle(200,200,150);
  fill();
  //keep the rest of the drawing in the circle
  clip();
  
  //change fill color back to black for squares
  fillcolor('black');
  
  //x will take on values 20, 60, 100...
  for (x=20;x<width;x=x+40)
    //for each value of x, y takes on 20, 60...
    for (y=20;y<height;y=y+40){
      rect(x-10,y-10,20,20);
      fill();
    }  
}