如何在 Phaser 游戏中反向生成平台？

Question

我正在创造一个无尽的跑步者。在按下左箭头键的那一刻，玩家向左移动，相机跟随他，玩家下方的地砖在离开右侧的世界边界时被破坏，并在进入世界边界之前重新创建在左侧。这使他可以永远奔跑而不会耗尽地面。我的代码运行良好，但有一个问题：我希望玩家跑到游戏的右侧，而不是左侧。请注意，我不需要玩家能够双向移动。我可以通过执行以下操作使相机向右而不是向左跟随玩家：我从 -this in 中删除负片

this.world.setBounds(-this.player.yChange, 0, ...);

原来如此

this.world.setBounds(this.player.yChange, 0, ...);

现在，当按下右箭头键时，摄像机会跟随玩家向右奔跑，但地面瓷砖不会再生，他会跑出地面。所以基本上我需要扭转地面再生的方向，但我不知道该怎么做。由于一切都在向左工作，我相信这是一些简单的设置，也许是一些需要积极的负面因素？我一直在这几天，无法弄清楚。有没有人能看到一个明显的解决方案？我会很感激的。

我的代码如下，或查看 codepen 链接： https://codepen.io/clownhead/pen/BqyqOm

    var Jumper = function() {};
Jumper.Play = function() {};

Jumper.Play.prototype = {

  preload: function() {
    this.load.image( 'hero', 'https://s3-us-west-2.amazonaws.com/s.cdpn.io/836/dude.png' );
    this.load.image( 'pixel', 'https://s3-us-west-2.amazonaws.com/s.cdpn.io/836/pixel_1.png' );
  },

  create: function() {
    // background color
    this.stage.backgroundColor = '#6bf';

    // scaling
    this.scale.scaleMode = Phaser.ScaleManager.SHOW_ALL;
    this.scale.maxWidth = this.game.width;
    this.scale.maxHeight = this.game.height;
    this.scale.pageAlignHorizontally = true;
    this.scale.pageAlignVertically = true;
    this.scale.setScreenSize( true );

    // physics
    this.physics.startSystem( Phaser.Physics.ARCADE );

    // camera and platform tracking vars
    this.cameraXMin = 99999;
    this.platformXMin = 99999;

    // create platforms
    this.platformsCreate();

    // create hero
    this.heroCreate();

    // cursor controls
    this.cursor = this.input.keyboard.createCursorKeys();
  },

  update: function() {
    // this is where the main magic happens
    // the x offset and the width of the world are adjusted
    // to match the furthest point the hero has reached
    this.world.setBounds(-this.hero.xChange, 0, this.world.width + this.hero.xChange, this.game.height);

    // the built in camera follow methods won't work for our needs, we create a custom one

    this.cameraXMin = Math.min( this.cameraXMin, this.hero.x - this.game.width + 130 );
    this.camera.x = this.cameraXMin;

    // hero collisions and movement
    this.physics.arcade.collide( this.hero, this.platforms );
    this.heroMove();

     // these are pooled so they are very performant
    this.platforms.forEachAlive( function( elem ) {
      this.platformXMin = Math.min( this.platformXMin, elem.x );
      if( elem.x > this.camera.x + this.game.width ) {
        elem.kill();
        this.platformsCreateOne( this.platformXMin - 70, this.world.height - 50, 50 );
      }
    }, this );
  },

  shutdown: function() {
    // reset everything, or the world will be messed up
    this.world.setBounds( 0, 0, this.game.width, this.game.height );
    this.cursor = null;
    this.hero.destroy();
    this.hero = null;
    this.platforms.destroy();
    this.platforms = null;
  },

  platformsCreate: function() {
    // platform basic setup
    this.platforms = this.add.group();
    this.platforms.enableBody = true;
    this.platforms.createMultiple( 10, 'pixel' );

    // create a batch of platforms that start to move across the level
    for( var i = 0; i < 9; i++ ) {
      this.platformsCreateOne( this.world.width - 70 - 70 * i, this.world.height - 50, 50);
    }
  },

  platformsCreateOne: function( x, y, width ) {
    // this is a helper function since writing all of this out can get verbose elsewhere
    var platform = this.platforms.getFirstDead();
    platform.reset( x, y );
    platform.scale.x = width;
    platform.scale.y = 16;
    platform.body.immovable = true;
    return platform;
  },

  heroCreate: function() {
    // basic hero setup
    this.hero = game.add.sprite( this.world.centerX, this.world.height - 69, 'hero' );
    this.hero.anchor.set( 0.5 );

    // track where the hero started and how much the distance has changed from that point
    this.hero.xOrig = this.hero.x;
    this.hero.xChange = 0;

    // hero collision setup
    // disable all collisions except for down
    this.physics.arcade.enable( this.hero );
    this.hero.body.gravity.y = 500;
    this.hero.body.checkCollision.up = false;
    this.hero.body.checkCollision.left = false;
    this.hero.body.checkCollision.right = false;
  },

  heroMove: function() {
    // handle the left and right movement of the hero
    if( this.cursor.left.isDown ) {
      this.hero.body.velocity.x = -400;
    } else if( this.cursor.right.isDown ) {
      this.hero.body.velocity.x = 400;
    } else {
      this.hero.body.velocity.x = 0;
    }

    // handle hero jumping
    if( this.cursor.up.isDown && this.hero.body.touching.down ) {
      this.hero.body.velocity.y = -350;
    } 

    // wrap world coordinated so that you can warp from top to bottom
    this.world.wrap( this.hero, this.hero.width / 2, false );

    // track the maximum amount that the hero has travelled
    this.hero.xChange = Math.max( this.hero.xChange, Math.abs( this.hero.x - this.hero.xOrig ) );

  }
}

var game = new Phaser.Game( 500, 300, Phaser.CANVAS, '' );
game.state.add( 'Play', Jumper.Play );
game.state.start( 'Play' );

Answer 1

所以你的代码的相关位基本上是这样的：

this.camera.x = this.cameraXMin;

如果我们查看代码的行为方式，它会跟踪英雄所在的位置，然后考虑英雄所在的位置。

this.cameraXMin = Math.min( this.cameraXMin, this.hero.x - this.game.width + 130 );

只要英雄向左移动就可以很好地工作，因为x 会越来越小。但是，一旦您开始向右移动，它们最初开始的位置（例如 0）将始终低于它们去的位置（会越来越高）。

因此，您需要Math.max，而不是跟踪Math.min。您需要对代码进行更多重构，但进行以下调整将使您走上正确的道路。

在create 中，您必须设置更好的默认值：

// Instead of setting this to a high number, I would start it where the camera starts. Or just set it to 0.
this.cameraXMin = this.camera.x;

现在在你的update，有它Math.max：

this.cameraXMin = Math.max( this.cameraXMin, this.hero.x - this.game.width + 130 );

您的平台代码也需要更改，但以上内容应该让您了解需要更改的内容。