javascript - 如何在phaser框架中实现按键长按加速

Question

我正在为客户开发我的第一个移相器游戏。比赛是一辆向前行驶的汽车，它有两分钟的时间到达目标。

我想在按下向上键的同时逐步提高车速，直到达到限速。

我通过以下方式移动赛道而不是汽车:

this.highway2 = game.add.tileSprite(game.world.centerX,game.world.height/2,   game.cache.getImage('highway').width, game.cache.getImage('highway').height, 'highway');
this.highway2.anchor.setTo(0.5,0.5);
this.highway2.autoScroll(0,1000);

所以，我的问题是:
如何控制 autoScroll 的速度来模拟加速？有没有办法知道按下一个键的时间？这是完成这项工作的正确方法吗？

提前致谢。

Answer 1

好吧，我不知道这是否是更好的方法，但它工作得很好。只需设置速度限制并在更新功能中跟踪它。

var playState = {
create: function(){

    this.setInitialValues();


    game.physics.startSystem(Phaser.Physics.ARCADE);        
    this.cursor = game.input.keyboard.createCursorKeys();

    //highway       
    this.highway2 = game.add.tileSprite(game.world.centerX,game.world.height/2, game.cache.getImage('highway').width, game.cache.getImage('highway').height, 'highway');
    this.highway2.anchor.setTo(0.5,0.5);
    this.highway2.autoScroll(0,0);

    //car
    this.player = game.add.sprite(game.world.centerX+10, game.world.height-150, 'player');
    this.player.anchor.setTo(0.5,0.5);
    game.physics.arcade.enable(this.player);

    //other things

},
update: function(){
    this.movePlayer();  
},
movePlayer: function(){
    // move left and right
    // If the left arrow key is pressed 
    if (this.cursor.left.isDown) 
    {
        // Move the player to the left
        this.player.body.velocity.x = -200; 
    }
    // If the right arrow key is pressed
    else if (this.cursor.right.isDown) 
    { // Move the player to the right 
        this.player.body.velocity.x = 200;
    }
    // If neither the right or left arrow key is pressed
    else 
    {
        // Stop the player 
        this.player.body.velocity.x = 0;
    }

    //speed up and speed down
    if (this.cursor.up.isDown)
    {
        if(this.currentSpeed < this.maxSpeed )
        {
            this.currentSpeed+=10;
            this.highway2.autoScroll(0,this.currentSpeed);
        }

    }
    else{
            if(this.currentSpeed > 0 )
        {
            this.currentSpeed-=10;
            this.highway2.autoScroll(0,this.currentSpeed);
        }
    }

    if (this.cursor.down.isDown)
    {
        if(this.currentSpeed > 0 )
        {
            this.currentSpeed-=30;
            this.highway2.autoScroll(0,this.currentSpeed);
        }
    }
},
setInitialValues: function(){
    this.maxSpeed=1500;
    this.currentSpeed=0;
}
}