在THREE.js中使用纹理

Question

我开始使用THREE.js,我正在尝试绘制一个带有纹理的矩形,由单个光源照亮.我认为这很简单(为简洁起见省略了HTML):

function loadScene() {
    var world = document.getElementById('world'),
        WIDTH = 1200,
        HEIGHT = 500,
        VIEW_ANGLE = 45,
        ASPECT = WIDTH / HEIGHT,
        NEAR = 0.1,
        FAR = 10000,

        renderer = new THREE.WebGLRenderer(),
        camera = new THREE.Camera(VIEW_ANGLE, ASPECT, NEAR, FAR),
        scene = new THREE.Scene(),
        texture = THREE.ImageUtils.loadTexture('crate.gif'),
        material = new THREE.MeshBasicMaterial({map: texture}),
        // material = new THREE.MeshPhongMaterial({color: 0xCC0000});
        geometry = new THREE.PlaneGeometry(100, 100),
        mesh = new THREE.Mesh(geometry, material),
        pointLight = new THREE.PointLight(0xFFFFFF);

    camera.position.z = 200;    
    renderer.setSize(WIDTH, HEIGHT);
    scene.addChild(mesh);
    world.appendChild(renderer.domElement);
    pointLight.position.x = 50;
    pointLight.position.y = 50;
    pointLight.position.z = 130;
    scene.addLight(pointLight); 
    renderer.render(scene, camera);
}

问题是,我看不到任何东西.如果我更改材料并使用注释的材料,则会出现正方形,如我所料.注意

• 纹理是256x256,因此它的边是2的幂
• 在加载主体时实际调用该函数; 实际上它适用于不同的材料.
• 即使我从Web服务器提供文件也不起作用,因此不允许加载图像的跨域策略问题.

我做错了什么？

Answer 1

在加载图像时,渲染器已经绘制了场景,因此为时已晚.解决方案是改变

texture = THREE.ImageUtils.loadTexture('crate.gif'),

成

texture = THREE.ImageUtils.loadTexture('crate.gif', {}, function() {
    renderer.render(scene);
}),

Answer 2

Andrea解决方案是绝对正确的,我将基于相同的想法编写另一个实现.如果您查看了THREE.ImageUtils.loadTexture()源代码,您会发现它使用了javascript Image对象.加载所有图像后触发$(window).load事件!所以在那个事件中我们可以用已经加载的纹理渲染我们的场景......

• CoffeeScript的

  $(document).ready ->
  
      material = new THREE.MeshLambertMaterial(map: THREE.ImageUtils.loadTexture("crate.gif"))
  
      sphere   = new THREE.Mesh(new THREE.SphereGeometry(radius, segments, rings), material)
  
      $(window).load ->
          renderer.render scene, camera
  

• JavaScript的

  $(document).ready(function() {
  
      material = new THREE.MeshLambertMaterial({ map: THREE.ImageUtils.loadTexture("crate.gif") });
  
      sphere = new THREE.Mesh(new THREE.SphereGeometry(radius, segments, rings), material);
  
      $(window).load(function() {
          renderer.render(scene, camera);
      });
  });
  

谢谢...

Answer 3

在three.js的r75版本中,您应该使用:

var loader = new THREE.TextureLoader();
loader.load('texture.png', function ( texture ) {
  var geometry = new THREE.SphereGeometry(1000, 20, 20);
  var material = new THREE.MeshBasicMaterial({map: texture, overdraw: 0.5});
  var mesh = new THREE.Mesh(geometry, material);
  scene.add(mesh);
});

Answer 4

在three.js所版本R82 TextureLoader是用来加载纹理的对象.

加载一个纹理(源代码,演示)

Extract(test.js):

var scene = new THREE.Scene();
var ratio = window.innerWidth / window.innerHeight;
var camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight,
  0.1, 50);

var renderer = ...

[...]

/**
 * Will be called when load completes.
 * The argument will be the loaded texture.
 */
var onLoad = function (texture) {
  var objGeometry = new THREE.BoxGeometry(20, 20, 20);
  var objMaterial = new THREE.MeshPhongMaterial({
    map: texture,
    shading: THREE.FlatShading
  });

  var mesh = new THREE.Mesh(objGeometry, objMaterial);

  scene.add(mesh);

  var render = function () {
    requestAnimationFrame(render);

    mesh.rotation.x += 0.010;
    mesh.rotation.y += 0.010;

    renderer.render(scene, camera);
  };

  render();
}

// Function called when download progresses
var onProgress = function (xhr) {
  console.log((xhr.loaded / xhr.total * 100) + '% loaded');
};

// Function called when download errors
var onError = function (xhr) {
  console.log('An error happened');
};

var loader = new THREE.TextureLoader();
loader.load('texture.jpg', onLoad, onProgress, onError);

加载多个纹理(源代码,演示)

在此示例中,纹理在网格的构造函数中加载,使用Promises加载多个纹理.

Extract(Globe.js):

使用Object3D在同一容器中具有两个网格来创建一个新容器:

var Globe = function (radius, segments) {

  THREE.Object3D.call(this);

  this.name = "Globe";

  var that = this;

  // instantiate a loader
  var loader = new THREE.TextureLoader();

一个地图textures,其中每个对象都包含url一个纹理文件,并val用于存储Three.js 纹理对象的值.

  // earth textures
  var textures = {
    'map': {
      url: 'relief.jpg',
      val: undefined
    },
    'bumpMap': {
      url: 'elev_bump_4k.jpg',
      val: undefined
    },
    'specularMap': {
      url: 'wateretopo.png',
      val: undefined
    }
  };

promises数组,对于map中的每个对象,textures在数组中推送一个新的Promise texturePromises,每个Promise都会调用loader.load.如果值entry.val是有效THREE.Texture对象,则解析promise.

  var texturePromises = [], path = './';

  for (var key in textures) {
    texturePromises.push(new Promise((resolve, reject) => {
      var entry = textures[key]
      var url = path + entry.url

      loader.load(url,
        texture => {
          entry.val = texture;
          if (entry.val instanceof THREE.Texture) resolve(entry);
        },
        xhr => {
          console.log(url + ' ' + (xhr.loaded / xhr.total * 100) +
            '% loaded');
        },
        xhr => {
          reject(new Error(xhr +
            'An error occurred loading while loading: ' +
            entry.url));
        }
      );
    }));
  }

Promise.all将promise数组texturePromises作为参数.这样做会使浏览器等待所有承诺解决,当他们这样做时,我们可以加载几何和材料.

  // load the geometry and the textures
  Promise.all(texturePromises).then(loadedTextures => {

    var geometry = new THREE.SphereGeometry(radius, segments, segments);
    var material = new THREE.MeshPhongMaterial({
      map: textures.map.val,
      bumpMap: textures.bumpMap.val,
      bumpScale: 0.005,
      specularMap: textures.specularMap.val,
      specular: new THREE.Color('grey')
    });

    var earth = that.earth = new THREE.Mesh(geometry, material);
    that.add(earth);
  });

对于云球体,只需要一个纹理:

  // clouds
  loader.load('n_amer_clouds.png', map => {
    var geometry = new THREE.SphereGeometry(radius + .05, segments, segments);
    var material = new THREE.MeshPhongMaterial({
      map: map,
      transparent: true
    });

    var clouds = that.clouds = new THREE.Mesh(geometry, material);
    that.add(clouds);
  });
}

Globe.prototype = Object.create(THREE.Object3D.prototype);
Globe.prototype.constructor = Globe;