Learn Intermediate OOP by Building a Platformer Game - Step 63

[LamVN]

Tell us what’s happening: I don’t under stand how calling the animate() function after the click event got fired when we click on the start button and pressing arrow keys will get the movePlayer() called work. All I understand is that after we clicked to the start button, the animate() function would be called and we would see the rectangle moving down a lil bit compared to the default position, but how it work? I dont understand why we passed the animate function itselft to the requestAnimationfuntion(). And about pressing the arrow keys, we only update the x and y values inside the velocity object without calling the update function, so how could the rectangle got redrawn again? Could anyone please explain to me about that?

Your code so far

const startGame = () => {
  canvas.style.display = "block";
  startScreen.style.display = "none";
  animate();
}

const animate = () => {
  requestAnimationFrame(animate);
  ctx.clearRect(0, 0, canvas.width, canvas.height);
  player.update();

  if (keys.rightKey.pressed && player.position.x < proportionalSize(400)) {
    player.velocity.x = 5;
  } else if (keys.leftKey.pressed && player.position.x > proportionalSize(100)) {
    player.velocity.x = -5;
  } else {
    player.velocity.x = 0;
  }
}
window.addEventListener("keydown", ({ key }) => {
  movePlayer(key, 8, true);
});

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Challenge Information:

Learn Intermediate OOP by Building a Platformer Game - Step 63

freeCodeCamp.org