If noLoop() is run in setup(), the code in draw() is only run once. In this example, click the mouse to run the loop() function to cause the draw() the run continuously.

Highlighted Features

• noLoop()
• loop()

/**
 * Loop. 
 * 
 * If noLoop() is run in setup(), the code in draw() 
 * is only run once. In this example, click the mouse 
 * to run the loop() function to cause the draw() the 
 * run continuously. 
 */

float y = 180;
 
// The statements in the setup() function 
// run once when the program begins
void setup() {
  size(640, 360);  // Size should be the first statement
  stroke(255);     // Set stroke color to white
  noLoop();
}

void draw() { 
  background(0);  // Set the background to black
  line(0, y, width, y);  
  y = y - 1; 
  if (y < 0) { 
    y = height; 
  } 
} 

void mousePressed() {
  loop();
}