Phaser P2 Sprite Scale Scale更改不适用于所有组儿童

Question

我希望这段代码能解释我想要做什么。我有一张台球桌，如果球离得足够近，我希望球能够加速进入球袋。在这一点上，我还没有检查距离，只是想弄清楚如何去做。

我相信有更好的方法！

  balls.forEachAlive(
    pockets.forEachAlive( moveBallTowardPocket, this), this);

更新：以下代码正在工作，除了一件事，前五个口袋上的球的比例发生变化。加速适用于所有球到所有口袋。比例变化仅适用于最后一个口袋，而不是前五个。

function update() {
  pockets.forEachAlive(function(pocket) {
    accelerateBallToPocket(flipper, pocket, 60);
    balls.forEachAlive(function(ball) {
      accelerateBallToPocket(ball, pocket, 60);
    });
  });
  //...
}

function accelerateBallToPocket(ball, pocket, speed) {
  if (typeof speed === 'undefined') {
    var speed = 120;
  }
  var pocket_body_x = pocket.body.x;
  var pocket_body_y = pocket.body.y;
  var ball_body_x   = ball.body.x;
  var ball_body_y   = ball.body.y;

  // move ball toward pocket if close enough
  var dx = ball_body_x - pocket_body_x;  //distance ship X to enemy X
  var dy = ball_body_y - pocket_body_y;  //distance ship Y to enemy Y
  var dist = Math.sqrt(dx*dx + dy*dy);   //pythagoras

  if (dist < pocket_radius * pocket_leniency_factor) {

    // accelerate ball to pocket on right angle
    var angle = Math.atan2(pocket.y - ball.y,
                             pocket.x - ball.x);
    ball.body.rotation = angle + game.math.degToRad(90);
    ball.body.force.x = Math.cos(angle) * speed;
    ball.body.force.y = Math.sin(angle) * speed;

    // change scale
    // FIXME only works on the last pocket lower right
    if (ball === flipper) {
      ball.scale.setTo(Math.tan(pocket.x - ball.x),
                         Math.tan(pocket.y - ball.y));
    } else {
      ball.scale.setTo(Math.sin(pocket.x - ball.x),
                         Math.cos(pocket.y - ball.y));
    }
  } else {
    // reset the scale when the ball is out of range of the pocket
    ball.scale.setTo(1.0, 1.0);
  }
}

第二次更新： 以下，基于解决方案，让我再次朝着正确的方向前进，我认为......

  for (var i = 0; i < pockets.children.length; i++) {
    accelerateBallToPocket(cue, pockets.children[i], 60);
    if (cue.pocketing) break;
  }

  for (var i = 0; i < balls.children.length; i++) {
    if (balls.children[i].pocketing) continue;
    for (var j = 0; j < pockets.children.length; j++) {
      accelerateBallToPocket(balls.children[i], pockets.children[j], 60);
      if (balls.children[i].pocketing) return;
    }
  }

Answer 1

好的，问题是如果球没有靠近口袋，您将比例设置为 1。而且，当您检查每个球与每个球袋时，总会有一个球袋（在循环中稍后检查），球也没有关闭，除了球袋列表中的最后一个球袋。因此，即使将球标尺设置为正确的值，在检查下一个pocket 时也会将其重置。

你可以做的是检查一个球是否靠近至少一个口袋，如果是，那么它不能靠近其他口袋，所以你不会再次检查其他口袋。

// Consider that every ball is not inside a pocket
balls.forEachAlive(function(ball) {
   ball.inPocket = false;
});
flipper.inPocket = false; // You should really add the flipper to the balls group to remove duplicate code

pockets.forEachAlive(function(pocket) {
    if(!flipper.inPocket) accelerateBallToPocket(flipper, pocket, 60);
    balls.forEachAlive(function(ball) {
      if(!ball.inPocket) accelerateBallToPocket(ball, pocket, 60);
    });
  });

然后，在你的移动函数中，如果球靠近口袋，你必须将 inPocket 成员设置为 true。

function accelerateBallToPocket(ball, pocket, speed) {

    ...

    if (ball === flipper) {
      ball.scale.setTo(Math.tan(pocket.x - ball.x),
                         Math.tan(pocket.y - ball.y));
      ball.inPocket = true;
    } else {
      ball.scale.setTo(Math.sin(pocket.x - ball.x),
                         Math.cos(pocket.y - ball.y));
      ball.inPocket = true;
    }
  } else {
    // reset the scale when the ball is out of range of the pocket
    ball.scale.setTo(1.0, 1.0);
  }
}

另一种方法是颠倒循环顺序，首先遍历所有球并为每个球检查每个口袋，一旦你发现它在口袋中，继续外循环（跳过检查其他口袋）。为此，您的accelerateBall 函数应返回true 或false，当球离口袋足够近时为true，否则为false。

我会像这样重写你的迭代：

  for (var i = 0; i < pockets.children.length; i++) {
    accelerateBallToPocket(cue, pockets.children[i], 60);
    if (cue.pocketing) break;
  }

  // Stumped...
  for (var i = 0; i < balls.children.length; i++) {
    // No need for the check here, each ball should have pocketing=false, set at the top of the update loop
    // This means, that balls.children[i].pocketing will always be false here
    for (var j = 0; j < pockets.children.length; j++) {
      accelerateBallToPocket(balls.children[i], pockets.children[j], 60);
      if (balls.children[i].pocketing) break; // stop checking the rest of the pockets for this ball
    }
  }