javascript - 传递一个变量以一定 Angular 移动子弹

Question

所以基本上我目前正在我的游戏中实现射击光标机制。我有一个 mousemove eventListener 来检查鼠标坐标并计算我的 Angular 色应该射击的 Angular 。我只需要将最终的 vx 和 vy 变量从我的 handleMouse 函数传递到我的更新函数，但我不知道如何做。这可能是一个非常简单的解决方案，但由于我对编程还很陌生，所以我无法理解它。非常感谢。

window.addEventListener("mousemove", handleMouse, false);

function getMousePosition(e){
    var x, y;
    x = e.clientX - backgroundCanvas.getBoundingClientRect().left;
    y = e.clientY - backgroundCanvas.getBoundingClientRect().top;
    return {x:x, y:y};
}

function handleMouse(e){    
    var pos = getMousePosition(e);
    posx = pos.x; //mouse x position
    posy = pos.y; //mouse y position

    var delta = {x: posx - player.x, y: posy - player.y}; //y2 - y1, x2 - x1
    var angle = Math.atan2(delta.y, delta.x) ; 

    var vx = Math.cos(angle - (Math.PI/2)) * game.bulletSpeed;
    var vy = Math.sin(angle - (Math.PI/2)) * game.bulletSpeed;
    return {vx:vx, vy:vy};
}

function update(){
    //move bullets - this is where I need to pass the vx and vy variables
    var vector = handleMouse(e); // this is probably wrong
    vx = vector.vx;
    vy = vector.vy;

    for (i in game.bullets){
        game.bullets[i].x -= vx;
        game.bullets[i].y -= vy;    
    }
}

Answer 1

也许这会有所帮助，假设您直接想将 handleMouse 方法中的 vx 和 vy 变量传递给 update 方法。

function handleMouse(e){    
    var pos = getMousePosition(e);
    posx = pos.x; //mouse x position
    posy = pos.y; //mouse y position

    var delta = {x: posx - player.x, y: posy - player.y}; //y2 - y1, x2 - x1
    var angle = Math.atan2(delta.y, delta.x) ; 

    var vx = Math.cos(angle - (Math.PI/2)) * game.bulletSpeed;
    var vy = Math.sin(angle - (Math.PI/2)) * game.bulletSpeed;

    //call update method
    update(vx, vy);

    return {vx:vx, vy:vy};
}

和更新方法

function update(vx, vy){   
    for (i in game.bullets){
        game.bullets[i].x -= vx;
        game.bullets[i].y -= vy;    
    }
}