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.

Patterns.

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

 
void setup() {
  size(640, 360);
  background(102);
}

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);
  stroke(speed);
  ellipse(x, y, speed, speed);
}