Examples to explain three.js loading obj model

The main example of this article introduces the loading of obj model by three.js. Three.js is a webGL framework and is widely used due to its ease of use. If you want to learn webGL, it is a good choice to abandon those complicated native interfaces and start with this framework. Okay, let me introduce you to three.js loading obj model through a piece of code. The specific code is as follows:

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    <script></script>
    <script></script>
    <script>
      var scene = null;
      var camera = null;
      var renderer = null;
      var mesh = null;
      var id = null;
      function init() {
        renderer = new THREE.WebGLRenderer({//渲染器
          canvas: document.getElementById(&#39;mainCanvas&#39;)//画布
        });
        renderer.setClearColor(0x000000);//画布颜色
        scene = new THREE.Scene();//创建场景
        camera = new THREE.OrthographicCamera(-5, 5, 3.75, -3.75, 0.1, 100);//正交投影照相机
        camera.position.set(15, 25, 25);//相机位置
        camera.lookAt(new THREE.Vector3(0, 2, 0));//lookAt()设置相机所看的位置
        scene.add(camera);//把相机添加到场景中
        var loader = new THREE.OBJLoader();//在init函数中，创建loader变量，用于导入模型
        loader.load(&#39;libs/port.obj&#39;, function(obj) {//第一个表示模型路径，第二个表示完成导入后的回调函数，一般我们需要在这个回调函数中将导入的模型添加到场景中
          obj.traverse(function(child) {
            if (child instanceof THREE.Mesh) {
              child.material.side = THREE.DoubleSide;
            }
          });
          mesh = obj;//储存到全局变量中
          scene.add(obj);//将导入的模型添加到场景中
        });
        var light = new THREE.DirectionalLight(0xffffff);//光源颜色
        light.position.set(20, 10, 5);//光源位置
        scene.add(light);//光源添加到场景中
        id = setInterval(draw, 20);//每隔20s重绘一次
      }
      function draw() {//们在重绘函数中让茶壶旋转：
        renderer.render(scene, camera);//调用WebGLRenderer的render函数刷新场景
        mesh.rotation.y += 0.01;//添加动画
        if (mesh.rotation.y > Math.PI * 2) {
          mesh.rotation.y -= Math.PI * 2;
        }
      }
    </script>
  
  
    <canvas></canvas>
  

Let’s take a look at how to use Three.js to load obj and mtl files

OBJ and MTL are the geometric model files and material files of the 3D model.

In the latest three.js version (r78), the previous OBJMTLLoader class has been deprecated.

Now to load OBJ and MTL files, you need to combine the two classes OBJLoader and MTLLoader to achieve this, which also provides operational flexibility.

In the following code, MTLLoader is first used to load the egg.mtl material file, and then the material is set to an OBJLoader object so that it can be applied when loading the obj model.

onProgress is the loading process callback function, and onError is the error handling function.

// model
var onProgress = function(xhr) {
  if (xhr.lengthComputable) {
    var percentComplete = xhr.loaded / xhr.total * 100;
    console.log(Math.round(percentComplete, 2) + '% downloaded');
  }
};
var onError = function(xhr) {};
THREE.Loader.Handlers.add(/\.dds$/i, new THREE.DDSLoader());
var mtlLoader = new THREE.MTLLoader();
mtlLoader.setPath('/uploads/160601/obj/');
mtlLoader.load('egg.mtl', function(materials) {
  materials.preload();
  var objLoader = new THREE.OBJLoader();
  objLoader.setMaterials(materials);
  objLoader.setPath('/uploads/160601/obj/');
  objLoader.load('egg.obj', function(object) {
    object.position.y = -0.5;
    scene.add(object);
  }, onProgress, onError);
});

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