Three.js 程序返回：“Cannot read property '0' of undefined”

Question

以下代碼用於an object according to四元數數據an object according to設置動畫：

var scene = new THREE.Scene();
var camera = new THREE.PerspectiveCamera( 75, window.innerWidth/window.innerHeight, 0.1, 1000 );

var renderer = new THREE.WebGLRenderer({antialias: true, alpha: true});
renderer.setSize( window.innerWidth, window.innerHeight );
document.body.appendChild( renderer.domElement );

var geometry = new THREE.BoxGeometry( 1, 0.3, 2 );
var material = new THREE.MeshBasicMaterial( { color: 0xf4b942 } );
var obj = new THREE.Mesh( geometry, material );
scene.add( obj );

var geometry = new THREE.BoxBufferGeometry(1, 0.3, 2 );
var edges = new THREE.EdgesGeometry(geometry);
var lines = new THREE.LineSegments(edges, new THREE.LineBasicMaterial({ color: 0x000000 }));
scene.add( lines );

camera.position.z = 5;
renderer.render(scene,camera);
var xpos_o = obj.rotation.x;
var ypos_o = obj.rotation.y;
var zpos_o = obj.rotation.z;
var xpos_lo = lines.rotation.x;
var ypos_lo = lines.rotation.y;
var zpos_lo = lines.rotation.z;

let i = 0; let m = 0;
var animate = function (quat_data) {
    requestAnimationFrame( animate );

    if (m % 5 == 0 || m == 0) {
        if (m !== 0) {i++;}

        if (i >= quat_data.length){
            obj.rotation.x = xpos_o;
            obj.rotation.y = ypos_o;
            obj.rotation.z = zpos_o;
            lines.rotation.x = xpos_lo;
            lines.rotation.y = ypos_lo;
            lines.rotation.z = zpos_lo;
            i=0; 
        }

        let quat = quat_data[i]; 

        var quaternion = new THREE.Quaternion(quat[0],quat[1],quat[2],quat[3]);
        obj.applyQuaternion(quaternion);
        lines.applyQuaternion(quaternion);

        renderer.render( scene, camera );    
    }

    m++;    
}

var animate1 = function() {

    var quat_data1 = [  [0.681492531,-0.014533572,0.711492547,-0.170668778  ], 
            [-0.81103207,0.125979118,0.555748976,-0.132257921  ],
            [-0.459080697,-0.267181198,-0.846533742,0.035103342  ],
            [0.874097952,-0.166578614,-0.244525976,0.385231457  ],
            ...

    animate(quat_data1);
}

var animate2 = function() {

    var quat_data2 = [[-0.395306087,-0.567475272,-0.168275478,-0.702416024  ], 
            [0.591221013,-0.226393713,-0.208636898,0.745435603  ],
            [-0.279990579,0.754847831,0.56444738,-0.182233852  ],
            [-0.419803039,-0.623439075,-0.538698243,-0.380648559  ],
            [0.878036311,0.088829796,-0.024437397,0.469642749  ],
            ...

    animate(quat_data2);
}

var animate3 = function() {

    var quat_data3 = [ [-0.17958507,0.232682609,-0.217296778,-0.930800793  ], 
            [-0.178598829,0.228014038,-0.2182292,-0.931927075  ],
            [-0.177601473,0.223351625,-0.219152185,-0.933029522  ],
            [-0.176574343,0.218685883,-0.220066047,-0.934113976  ],
            [-0.175533915,0.214015872,-0.22097227,-0.935177153  ],
            [-0.174483815,0.209350901,-0.221866773,-0.936217247  ],
            [-0.173407996,0.204681945,-0.222753878,-0.937238325  ],
            ...

    animate(quat_data3);
}

我省略了一些quaternion數據並用省略號代替它以節省空間。 開始部分只是建立場景的幾何形狀。 animate 函數采用quaternion數組。 requestAnimationFrame每次迭代后，m 增加 1，每次達到 5 的倍數時，執行動畫代碼。 （這是因為我想將requestAnimationFrame的 60 fps 轉換為 12 fps。）動畫代碼將 i 增加 1（移動到下一個quaternion ）並應用quaternion 。 如果 i 超過quaternion數據數組的長度，則它會循環回到數據的開頭並重置對象的原始方向。

還有其他三個函數animate1 、 animate2和animate3 ，它們使用不同的quaternion數據集來執行animate函數。

當我單擊 html 代碼中的按鈕來執行animate1 ，控制台在以下行中給我問題中所述的錯誤：

var quaternion = new THREE.Quaternion(quat[0],quat[1],quat[2],quat[3]);

Answer 1

問題是動畫（ requestAnimationFrame ）在錯誤的位置和錯誤的回調目標執行。 回調函數只傳遞一個參數，即時間值。

 var animate = function (quat_data) { requestAnimationFrame( animate ); // [...] let quat = quat_data[i]; var quaternion = new THREE.Quaternion(quat[0],quat[1],quat[2],quat[3]); // [...] }

您期望函數animate的輸入是動畫數據數組，但它是單個時間值。

你必須這樣做：

var animate = function (quat_data) {
    requestAnimationFrame( function() { animate(quat_data); } );

    // [...]
}