如何绘制具有tween动画效果的三js线几何图形

Question

我是Three.js.的新手

我想在三维空间上绘制曲线（基于一些参数方程），使用THREE.JS来说明绘制路径。

为了实现这一点，我尝试了两种方法：

方法一：更新几何体中的值：

var lineGeometry = new THREE.Geometry();
lineGeometry.vertices.push(new THREE.Vector3(starting_x,starting_y,starting_z));
var lineMaterial = new THREE.LineBasicMaterial({color: 0xffffff});
var line = new THREE.Mesh(lineGeometry, lineMaterial);
scene.add(line);

function render() {
    requestAnimationFrame(animate);
    //calculate x,y,z based on my equation  
    lineGeometry.vertices.push(new THREE.Vector3(x,y,z));
    renderer.render(scene, camera);
}

方法二：使用Tween.js更新功能在上引用

var lineGeometry = new THREE.Geometry();
lineGeometry.vertices.push(new THREE.Vector3(starting_x,starting_y,starting_z));
var lineMaterial = new THREE.LineBasicMaterial({color: 0xffffff});
var line = new THREE.Mesh(lineGeometry, lineMaterial);
scene.add(line);
var position = {x: -15, y: 0, z: 0};
var target = {x: 4, y: 0, z: -15};
var tween = new TWEEN.Tween(position).to(target, 8000);
tween.easing(TWEEN.Easing.Elastic.InOut);
tween.onUpdate(function() {
    lineGeometry.vertices.push(position.x, position.y, position.z);
});
tween.start();
animate();
function animate() {
    render();
    requestAnimationFrame(animate);
    TWEEN.update();
}
function render() {
    renderer.render(scene, camera);
}

我如何在这个链接中实现这一点（它在2D空间中，我试图在3D空间中实现）？

PS:我可以在场景中添加形状和线条，也可以用tween.js制作整个对象的动画。但问题是要制作线条的动画。请帮忙

Answer 1

谢谢大家，我终于解决了

1.我创建了一个缓冲几何体，通过指定其大小，该大小等于我需要画线的点数。

var buffer_geometry = new THREE.BufferGeometry();
buffer_geometry.attributes = {
            position: {
                itemSize: 3,
                array: new Float32Array(numberofpoints)
            }
        };

2.在渲染时保持位置数组以更新它

positions = buffer_geometry.attributes.position.array;

3.在更新函数中，每6个相邻点都由曲线上的x、y、z值更新：

            positions[ i * 6 ] = x;
            positions[ i * 6 + 1 ] = y;
            positions[ i * 6 + 2] = z;
            positions[ i * 6 + 3] = x + 0.1;
            positions[ i * 6 + 4] = y + 0.1;
            positions[ i * 6 + 5] = z + 0.1;