问使物体碰撞不影响重力/速度

EN

  var game = new Phaser.Game(800, 600, Phaser.AUTO, '', { preload: preload, create: create, update: update });

  var platforms;
  var player;
  var player1Bullets;

  function preload() {
          game.load.image('ground', 'assets/platform.png');
          game.load.spritesheet('dude', 'assets/doffaSmall.png', 57, 69);
  }

  var gameOver = false;
  var thing;
  var roofGroup;


  function CreatePlayer(name, x) {
        var chara = new APlayer(name, x);
        game.physics.arcade.enable(chara.character);
        chara.character.body.gravity.y = 20;
        chara.character.body.collideWorldBounds = true;
        chara.character.animations.add('left', [11, 12, 13, 14, 15, 16, 17, 18, 19, 20], 11, true);
        chara.character.animations.add('right', [8, 7, 6, 5, 4, 3, 2, 1, 0], 10, true);
        return chara;
  }


  function create() {

        game.physics.startSystem(Phaser.Physics.ARCADE);
    
        roofGroup = game.add.group();
        roofGroup.enableBody = true;
        var roof = roofGroup.create(0,0, 'ground');
        roof.scale.setTo(2,1);
        roof.body.immovable = true;
    
        platforms = game.add.group();
        platforms.enableBody = true;
        var ledge = platforms.create(100, 500, 'ground');
        ledge.scale.setTo(0.5, 0.5);
        platforms.addAll('body.velocity.y', -20)
        platforms.allowGravity = false;
        player = CreatePlayer('per', 96);

        player.leftKey = game.input.keyboard.addKey(Phaser.Keyboard.LEFT);
        player.rightKey = game.input.keyboard.addKey(Phaser.Keyboard.RIGHT);
        player.upKey = game.input.keyboard.addKey(Phaser.Keyboard.UP);
        player.shootKey = game.input.keyboard.addKey(Phaser.Keyboard.SPACEBAR);
        game.input.keyboard.addKeyCapture([ Phaser.Keyboard.LEFT, Phaser.Keyboard.RIGHT, Phaser.Keyboard.UP, Phaser.Keyboard.SPACEBAR, Phaser.Keyboard.W, Phaser.Keyboard.A, Phaser.Keyboard.D, Phaser.Keyboard.E  ]);
  }

  function killPlatform (platform, roof) {
       platform.kill();
  }

  function update() {
       if(platforms.countLiving() < 4) {
          var x = Math.floor((Math.random() * game.world.width) + 1);
          var ledge = platforms.create(x, game.world.height, 'ground');
          ledge.scale.setTo(0.5,0.5);
          platforms.addAll('body.velocity.y', -20);
         platforms.allowGravity = false;
    }
        game.physics.arcade.collide(platforms, roofGroup, killPlatform, null, this);
        player.move();
    }