mouse trail

mousetrail.pde

float[] x = new float[50];
float[] y = new float[50];
 
void setup() {
  size(450,450);
  smooth();
  noStroke();
   
  // reset all the numbers in both arrays
  for(int i = 0; i<x.length; i++) {
    x[i] = 0;
    y[i] = 0;
  }
   
}
void draw() {
   
  background(0);
   
  // now iterate 0 to the 2nd last item in the array
  for(int i = 0; i<x.length-1; i++) {
    // and shift all the values down one item
    x[i] = x[i+1];
    y[i] = y[i+1];
     
    // set the fill colour to be darker the
    // lower its index in the array
    fill(i*2);
    // and draw the circle at the position
    ellipse(x[i], y[i], i*4, i*4);
     
  }
   
  // set the last items in the array to match the mouse position
  x[x.length-1] = mouseX;
  y[y.length-1] = mouseY;
   
}