final int radius = 20;
int button;

void setup(){
  background(0);
  size(500,500);
  noStroke();


}
void draw(){

  ellipse(mouseX,mouseY,radius,radius);
}

void mousePressed(){
  switch(mouseButton){

    case LEFT:
    if(mouseButton ==LEFT){
      ellipse(mouseX,mouseY,radius,radius);
      fill (255);
           println("links ingedrukt = wit");    }

     break;

    case RIGHT:
    fill(0,255,0);
    println("rechts ingedrukt = groen");
    break;

    case CENTER:
    clear();
    println("clear surface");
    break;

    }
}

void keyReleased(){
  if(mouseButton==LEFT){
  }
  if(mouseButton==RIGHT){
  }
    }