如何在 three.js 中构建自定义平面几何？

Question

我想在 three.js 中创建一个平面，但点比默认点多（所以我不想使用 PlaneGeometry，因为我认为它不会让我定义自定义点）。原因是我希望能够动画或移动任何给定的时间点。

这是我目前所拥有的：

var camera;
var scene;
var renderer;
var mesh;

init();
animate();

function init() {

    scene = new THREE.Scene();
    camera = new THREE.PerspectiveCamera( 70, window.innerWidth / window.innerHeight, 1, 1000);

    var light = new THREE.DirectionalLight( 0xffffff );
    light.position.set( 0, 1, 1 ).normalize();
    scene.add(light);


    var geometry = new THREE.PlaneGeometry( 50, 50);  

    var texture = THREE.ImageUtils.loadTexture('images/03032122.png', {}, function() {
    renderer.render(scene, camera);
    })
    var material = new THREE.MeshBasicMaterial({map: texture, transparent: true })


    mesh = new THREE.Mesh(geometry, material );
    mesh.position.z = -50;
    scene.add( mesh );

    renderer = new THREE.WebGLRenderer({ alpha: true });
    renderer.setSize( window.innerWidth, window.innerHeight );

    renderer.setClearColor( 0xffffff, 1);
    document.body.appendChild( renderer.domElement );

    window.addEventListener( 'resize', onWindowResize, false );

    render();
}

function animate() {
    //mesh.scale.x+= 0.0003;


    render();
    requestAnimationFrame( animate );

}

function render() {
    renderer.render( scene, camera );
}


function onWindowResize() {
    camera.aspect = window.innerWidth / window.innerHeight;
    camera.updateProjectionMatrix();
    renderer.setSize( window.innerWidth, window.innerHeight );
    render();
}

我想做的是创建这样的东西：

http://www.math.ubc.ca/~cass/courses/m308-02b/projects/schweber/square%20tiles.gif

Answer 1

尝试向 THREE.PlaneGeometry 添加另外两个参数。

THREE.PlaneGeometry( 宽度 , 高度 , widthSegments , heightSegments )

查阅库（查看函数调用），查阅文档。

这也可能被使用：

http://threejs.org/docs/#Reference/Extras.Geometries/ParametricGeometry

Answer 2

注意 PlaneGeometry，它已被弃用（因此它将在下一个版本中删除）。请改用 PlaneBufferGeometry。

如果您想要“正常”平面划分，@pailhead 的答案是正确的。

如果您希望顶点具有其他位置，则必须为每个顶点构建几何顶点，这是其他东西*。

这也满足了您稍后移动/动画顶点的需要，您可以在创建几何图形后更改每个顶点的位置：

planeMesh.geometry.vertices[i].set(x,y,z);// this way you can move each vertex coordinates
planeMesh.geometry.verticesNeedUpdate=true;

---

* : 具有 4 个顶点（=2 个三角形）的平面示例：

var geo=new THREE.Geometry();
geometry.vertices.push(
    new THREE.Vector3(x1,y1,z1),//vertex0
    new THREE.Vector3(x2,y2,z2),//1
    new THREE.Vector3(x3,y3,z3),//2
    new THREE.Vector3(x4,y4,z4)//3
    );
geometry.faces.push(
    new THREE.Face3(2,1,0),//use vertices of rank 2,1,0
    new THREE.Face3(3,1,2)//vertices[3],1,2...
    );

当然，使这个几何图形成为平面的原因是 4 个顶点是共轴的。

当您创建具有许多面的几何图形时，您会明白需要笔和纸来绘制您的面 :) 根据您的几何图形，您还可以使用算法。

Answer 3

我创建了我的定制飞机，使用：

        // Plane
            var size = 500, step = 100;
            var geometry = new THREE.Geometry();
            for ( var i = - size; i <= size; i += step ) {

                geometry.vertices.push( new THREE.Vector3( - size, 0, i ) );
                geometry.vertices.push( new THREE.Vector3(   size, 0, i ) );

                geometry.vertices.push( new THREE.Vector3( i, 0, - size ) );
                geometry.vertices.push( new THREE.Vector3( i, 0,   size ) );

            }

            var material = new THREE.LineBasicMaterial( { color: 0x000000, opacity: 0.5 } );

            var line = new THREE.Line( geometry, material, THREE.LinePieces );
            scene.add( line );

Answer 4

如果你想添加一个带有自定义边框的平面，我建议你直接更改位置属性数组并更新几何点位置：

// Here you chose the divisions in x
    const x_lenght = 1 
    const divisions = 10
    
    let geometry = new THREE.PlaneBufferGeometry( x_lenght, 1, divisions, 1 )
    let material = new THREE.MeshPhongMaterial( { color: 0xecf0f1, wireframe: true } )
    
    let pointPos = geometry.getAttribute("position").array
        
    for (let i = 0; i < divisions + 1; i++) {
      let x = pointPos[3 * i] + x_lenght/2

      // This case is making y = x^2
      pointPos[3 * i + 1] = Math.pow(x, 2) 
      pointPos[3 * ( divisions + 1 ) + 3 * i + 1] = - pointPos[3 * i  + 1]
      
      console.log(`x = ${pointPos[3 * i]}; y = ${pointPos[3 * ( divisions + 1 ) + 3 * i + 1]}`)

        }
    
    pointPos.needsUpdate = true;
    
    mesh = new THREE.Mesh(geometry, material )

    scene.add(mesh)

这是我的例子https://codepen.io/ferrari212/pen/bGpgLBd?editors=0010