Move the cursor over the image to draw with a software tool which responds to the speed of the mouse.

Original Example: Pattern

// All Examples Written by Casey Reas and Ben Fry
// unless otherwise stated.
void setup()
  size(200, 200);

void draw() 
  // Call the variableEllipse() method and send it the
  // parameters for the current mouse position
  // and the previous mouse position
  variableEllipse(mouseX, mouseY, pmouseX, pmouseY);

// The simple method variableEllipse() was created specifically 
// for this program. It calculates the speed of the mouse
// and draws a small ellipse if the mouse is moving slowly
// and draws a large ellipse if the mouse is moving quickly 

void variableEllipse(int x, int y, int px, int py) 
  float speed = abs(x-px) + abs(y-py);
  ellipse(x, y, speed, speed);