Keypresses/Updates 调用不正确？

Question

我正尝试在 Javascript 中制作游戏，但目前我已停滞不前。我正在尝试检测按键并检查它们是否不断按下以移动角色。这是我使用的代码：

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;
    }
}

当我按任何键时，这不起作用。对于一个更好的程序员来说，应该是一个相当容易发现的错误。是不是对eventListeners或者requestAnimationFrame的理解不好？如果是，请告诉我如何修复它。谢谢

Answer 1

我发现您的代码有一些需要改进的地方：

您永远不会调用 INIT() 函数，因此该代码永远不会运行。
您不应在 INIT 函数中使用 requestAnimationFrame。那里有很多代码不必每帧运行。
创建一个 function render(){...} 在 INIT 结束时调用或在调用 INIT 后直接调用。渲染函数应该有 requestAnimationFrame(render)
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>

Keypresses/Updates 调用不正确？

Keypresses/Updates not being called properly?

javascript

three.js

addeventlistener

requestanimationframe