update screen only when an event occurs

divya191 · March 2014

Hi all Is it possible to update the screen only when an event occurs (like a key is pressed), instead of at a specified framerate?

_vk · March 2014

You can use noLoop() and then redraw()

PVector pos;

void setup() {
  size(300, 300);
  pos = new PVector(random(width), random(height));
  background(255);

  // no loop ...
  noLoop();
}


void draw() {

  //if looping color would change each frame, but not : )
  fill(color(random(255)));
  rect(width/2, height/2, 40, 40);


  fill(200, 30, 200);
  ellipse( pos.x, pos.y, 30, 30);

  // frame we currently are
  frame.setTitle(nf(frameCount,4));
}

void keyPressed() {
  pos = new PVector(random(width), random(height));
  background(255);

  // draw once again...
  redraw();
}

GoToLoop · March 2014

A big bunch of online examples which uses noLoop() & redraw() couple in order to react only when an event triggers:

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