javascript - 按键/更新未正确调用？

Question

我正在尝试用 Javascript 制作游戏，但目前我已经陷入停滞。我正在尝试检测按键并检查它们是否不断按下以移动 Angular 色。这是我正在使用的代码:

var THREE;
var keys;
var update;
var scene = new THREE.Scene();
var renderer = new THREE.WebGLRenderer();
var player_fov = 45;
var player_aspect = window.innerWidth / window.innerHeight;
var player_near = 0.1;
var player_far = 10000;
var player_camera = new THREE.PerspectiveCamera(player_fov, player_aspect, player_near, player_far);
var player_material = new THREE.MeshNormalMaterial({color: 0xd0bd4b});
var player_geometry = new THREE.BoxGeometry(1,1,1,1);
var player = new THREE.Mesh(player_geometry, player_material);


function INIT()
{
    scene.add(player);
    player_camera.position.z = 5;
    window.addEventListener('keydown', function (e) {
        keys.keys = (keys.keys || []);
        keys.keys[e.keyCode] = true;
    });
    window.addEventListener('keyup', function (e){
        keys.keys[e.keyCode] = false;
    });
    requestAnimationFrame(INIT);
    renderer.setSize(window.innerWidth, window.innerHeight);
    document.body.appendChild(renderer.domElement);
    renderer.render(scene, player_camera);
    if(keys.keys && keys.keys[87]) //w
    {
        player.position.y += 1;
    }
    if(keys.keys && keys.keys[65]) //a
    {
        player.position.x -= 1;
    }
    if(keys.keys && keys.keys[83]) //s
    {
        player.position.y -= 1;
    }
    if(keys.keys && keys.keys[68]) //d
    {
        player.position.x += 1;
    }
}

当我按任意键时，这不起作用。对于更好的程序员来说，这应该是一个相当容易发现的错误。是不是对eventListeners或者requestAnimationFrame理解不好？如果是，请告诉我如何修复它。谢谢。

Answer 1

我发现您的代码中有一些需要改进的地方:

1. 您永远不会调用 INIT() 函数，因此代码永远不会运行。
2. 您不应该使用requestAnimationFrame在INIT函数中。其中有很多代码不必每帧都运行。
3. 创建 function render(){...}在 INIT 结束时或在调用 INIT 之后直接调用。渲染函数应该有 requestAnimationFrame(render)
4. 使用 javascript 对象而不是数组作为键。

我认为这些事情是最紧迫的。下面是一个工作示例。

var keys = {};
var scene = new THREE.Scene();
var renderer = new THREE.WebGLRenderer();
var player_fov = 45;
var player_aspect = window.innerWidth / window.innerHeight;
var player_near = 0.1;
var player_far = 10000;
var player_camera = new THREE.PerspectiveCamera(player_fov, player_aspect, player_near, player_far);
var player_material = new THREE.MeshNormalMaterial({color: 0xd0bd4b});
var player_geometry = new THREE.BoxGeometry(1,1,1,1);
var player = new THREE.Mesh(player_geometry, player_material);

INIT();

function INIT()
{
  document.addEventListener('keydown', function (e) {
    keys = (keys || {});
    keys[e.keyCode] = true;
  });

  document.addEventListener('keyup', function (e){
    keys[e.keyCode] = false;
  });
  
    scene.add(player);
    player_camera.position.z = 5;
  
    renderer.setSize(window.innerWidth, window.innerHeight);
    document.body.appendChild(renderer.domElement);
  
   render();
}


function render(){
    requestAnimationFrame(render);

    if(keys && keys[87]) //w
    {
      player.position.y += 0.2;
    }
    if(keys && keys[65]) //a
    {
      player.position.x -= 0.2;
    }
    if(keys && keys[83]) //s
    {
      player.position.y -= 0.2;
    }
    if(keys && keys[68]) //d
    {
      player.position.x += 0.2;
    }
    renderer.render(scene, player_camera);
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/r75/three.min.js"></script>