float x=10, y;
float xSpeed=0, ySpeed=40;
float accel = -0.98;

boolean launch=false;
PFont font;

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

  font = createFont("Arial",16,true);
  textFont(font);
  fill(255);
  textAlign(LEFT);

  text("atas-bawah -> kec. Y",50,40);
  text("kiri-kanan -> kec. X",50,60);
  text("enter -> launch",50,80);
}

void draw(){
  if (launch){
    fill(0,50);
    rect(0,0,width,height);
    fill(255);

    x += xSpeed;
    y += ySpeed + 0.5*accel;
    ySpeed += accel;
    ellipse(x, height-y, 5, 5);;

    if (y<=0){ ySpeed *=-0.75; y=0;}
  }

  else {
    fill(0,50);
    rect(45,0,150,25);
    fill(255);
    text(ySpeed,50,20);
    text(xSpeed,120,20);
  }

}

void keyPressed() {
  switch (keyCode) {
   case 10: launch = true;
            break;
   case 38: if (ySpeed<100) ySpeed++; else ySpeed=100;  //panah atas
            //println(ySpeed);
            break;
   case 40: if (ySpeed>0) ySpeed--; else ySpeed=0;  //panah bawah
            break;
   case 39: if (xSpeed<20) xSpeed+=0.25; else xSpeed=20;  //panah kanan
            break;
   case 37: if (xSpeed>0) xSpeed-=0.25; else xSpeed=0;  //panah kiri
            break;
   case 32: exit();
            break;
  }
}