如何在 Libgdx 中跟踪多个触摸事件?

问题描述

我正在使用 Libgdx 制作赛车游戏.我想触摸屏幕右侧的一半来加速，同时在不移除之前的触摸点的情况下再次触摸屏幕左侧的另一个来射击.我无法检测到后来的接触点.

I am making a racing game using Libgdx. I want to touch the half right side of screen to speed up, at the same time without removing previous touch point touch again another on the left side of the screen to fire a shot. I am unable to detect later touch points.

我已经搜索并获得了 Gdx.input.isTouched(int index) 方法，但无法确定如何使用它.我的屏幕触摸代码是:

I have searched and get Gdx.input.isTouched(int index) method, but cannot determin how to use it. My screen touch code is:

if(Gdx.input.isTouched(0) && world.heroCar.state != HeroCar.HERO_STATE_HIT){
    guiCam.unproject(touchPoint.set(Gdx.input.getX(), Gdx.input.getY(), 0));
    if (OverlapTester.pointInRectangle(rightScreenBounds, touchPoint.x, touchPoint.y)) {
       world.heroCar.state = HeroCar.HERO_STATE_FASTRUN;
       world.heroCar.velocity.y = HeroCar.HERO_STATE_FASTRUN_VELOCITY;
    }
} else {
    world.heroCar.velocity.y = HeroCar.HERO_RUN_VELOCITY;
}

if (Gdx.input.isTouched(1)) {
    guiCam.unproject(touchPoint.set(Gdx.input.getX(), Gdx.input.getY(), 0));
    if (OverlapTester.pointInRectangle(leftScreenBounds, touchPoint.x, touchPoint.y)) {
       world.shot();
    }
}

推荐答案

你会想要使用 Gdx.input.getX(int index) 方法.整数 index 参数表示活动指针的 ID.要正确使用它，您需要遍历所有可能的指针(如果两个人在平板电脑上有 20 根手指?).

You'll want to use the Gdx.input.getX(int index) method. The integer index parameter represents the ID of an active pointer. To correctly use this, you will want to iterate through all the possible pointers (in case two people have 20 fingers on the tablet?).

类似这样的:

boolean fire = false;
boolean fast = false;
final int fireAreaMax = 120; // This should be scaled to the size of the screen?
final int fastAreaMin = Gdx.graphics.getWidth() - 120;
for (int i = 0; i < 20; i++) { // 20 is max number of touch points
   if (Gdx.input.isTouched(i)) {
      final int iX = Gdx.input.getX(i);
      fire = fire || (iX < fireAreaMax); // Touch coordinates are in screen space
      fast = fast || (iX > fastAreaMin);
   }
}

if (fast) {
   // speed things up
} else {
   // slow things down
}

if (fire) {
   // Fire!
}

另一种方法是设置 InputProcessor 来获取输入事件(而不是像上面的例子那样轮询"输入).当指针进入其中一个区域时，您必须跟踪该指针的状态(以便在它离开时清除它).

An alternative approach is to setup an InputProcessor to get input events (instead of "polling" the input as the above example). And when a pointer enters one of the areas, you would have to track that pointer's state (so you could clear it if it left).

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