“This is the 26th day of my participation in the First Challenge 2022. For details: First Challenge 2022”

The sample code USES three. Js – r73 version: cdnjs.cloudflare.com/ajax/libs/t…

In this section, we will mainly explain how to import the model into three.js so that three.js can display our model. Let’s take a look.

Reconstruction project

Because of the example we are doing now, there is a lot of code that does not need to be changed very often, but there is also a lot of code, we can find the trouble to modify the code, so we refactor the project.

Our project is divided into the following parts:

Initialize the renderer
Initialization Scenario
Initializing the camera
Initialize light
Initialize the trackball
Initialize the GUI interface
Initialize performance monitoring
Initialize the color picker
Initialize object
Render loop
Listen for browser sizing changes

The parts we often need to revise:

The camera
The light
GUI interface
object
Update of data during rendering loop
Color change update

Later, when the implementation loads the model example, the project is refactored by function.

Threejs model loading process

How does threejs load models? Let’s take a look at the simplification of threejs loading models.

Model files on the server are stored as text
- The model files on the server are mostly stored vertex information of the model, not necessarily stored as text
Download the file from the browser to the local PC
Javascript parses model files through various Loaders to generate Mesh models
- Using loader, we can parse model files in various formats
- Javascript parses the text file and generates a geometry, which eventually generates a Mesh
Add the model to the scene and display it

Load VTK model

Vtk model is a textual 3D model file that can represent point and surface information and can be stored in text form in a human-readable manner. This file format is used a lot in scientific research.
We want to load VTK model, we need to prepare VTK model file (the previous section has been used) and parse VTK model file loader, I have helped you to prepare
VTK model file: Bunny.vtk.zip (890 kB)
Loader to parse VTK:Github.com/mrdoob/thre…
- All loaders are in threejs source directoryexamples/js/loadersIn, it is best to find the loaders corresponding to threejs, otherwise error prone

HTML page

Introduce our various JS resources

<! DOCTYPEhtml>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="Width = device - width, initial - scale = 1.0" />
    <title>Document</title>
    <script src=".. /.. /libs/three.js"></script>
    <script src=".. /.. /libs/dat.gui.js"></script>
    <script src=".. /.. /libs/TrackballControls.js"></script>
    <script src=".. /.. /libs/jscolor.js"></script>
    <script src=".. /.. /libs/stats.js"></script>
    <! -- Check whether the browser supports webGL -->
    <script src=".. /.. /libs/Detector.js"></script>
    <script src=".. /.. /libs/loaders/VTKLoader.js"></script>
  </head>
  <style type="text/css">
    body {
      margin: 0;
      overflow: hidden;
    }
    div#canvas-frame {
      border: none;
      cursor: pointer;
      width: 100%;
      height: 600px;
      background-color: #eeeeee;
    }
    #color-picker {
      position: absolute;
      bottom: 50px;
      left: 50px;
    }
  </style>
  <body>
    <div id="canvas-frame"></div>
    <script src="./index.js"></script>
  </body>
</html>

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Initialize the renderer

Since our model is white, we set the canvas to black

const clearColor = 0x000000; // 0xFFFFFF

function initRenderer() {
    width = document.getElementById('canvas-frame').clientWidth;
    height = document.getElementById('canvas-frame').clientHeight;
    renderer = new THREE.WebGLRenderer({
        antialias: true
    });
    renderer.setSize(width, height);
    document.getElementById('canvas-frame').appendChild(renderer.domElement);
    renderer.setClearColor(clearColor, 1.0);
}
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Initialization Scenario

function initScene() {
    scene = new THREE.Scene();
}
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Initializing the camera

function initCamera() {
    camera = new THREE.PerspectiveCamera(60, width / height, near, far);
    camera.position.z = 0.2;
    scene.add(camera);
}
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Initialize light

function initLight() {
    light = new THREE.DirectionalLight(0xffffff);
    light.position.set(200.200.1000).normalize();
    camera.add(light);
    camera.add(light.target);
}
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We added light to the camera to simulate light coming out of the camera

Initialize object

Creating the base Material

// Initialize the object
function initObject() {
    var material = new THREE.MeshLambertMaterial({ color: 0xffffff.side: THREE.DoubleSide });
}
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Loader loads the VTK model

We’re throughTHREE.VTKLoaderVTK model can be loaded to return onegeometry

var loader = new THREE.VTKLoader();
loader.load("https://threejs-models.vercel.app/models/vtk/bunny.vtk".function (geometry) {
    geometry.computeVertexNormals();
    var mesh = new THREE.Mesh(geometry, material);
    mesh.position.setY(- 0.09);
    scene.add(mesh);
});
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After the loader is loaded, obtain thegeometry, we can create a grid and add it to the scene.

Initialize various controls

Here the initialization of the ball, GUI interface, performance monitoring, color selector, browser window changes when processing, before all the actual combat, I will not introduce one

var param
function initGUI() {
    var ParamObj = function () {
        this.repeat = 4;
        this.wrap = 1000;
    }
    param = new ParamObj();
    const gui = new dat.GUI();
    / / GUI. The add (param, "repeat", 100, 100). The name (' texture repeat)
    / / GUI. The add (param, "wrap", 1000, 1002). The name (' texture around). Step (1)
}

var stats;
function initStats() {
    stats = new Stats();
    stats.showPanel(0); // 0: fps, 1: ms, 2: mb, 3+: custom
    // Map the stats interface to the upper left corner
    stats.domElement.style.position = 'absolute';
    stats.domElement.style.left = '0px';
    stats.domElement.style.top = '0px';
    document.body.appendChild(stats.dom);
}

function initColorPicker() {
    const colorPicker = document.createElement('div');
    colorPicker.id = 'color-picker'
    document.body.appendChild(colorPicker);
    const html = ``
    const colorPickerDom = document.querySelector('#color-picker')
    colorPickerDom.innerHTML = html;

    jscolor.install(colorPickerDom)

    jscolor.presets.default = {
        width: 141.// make the picker a little narrower
        position: 'top'.// position it to the right of the target
        previewPosition: 'right'.// display color preview on the right
        previewSize: 40.// make the color preview bigger
        format: 'hex'.previewSize: 40.closeButton: true.closeText: 'off'.palette: [
            '# 000000'.'#7d7d7d'.'# 870014'.'#ec1c23'.'#ff7e26'.'#fef100'.'#22b14b'.'#00a1e7'.'#3f47cc'.'#a349a4'.'#ffffff'.'#c3c3c3'.'#b87957'.'#feaec9'.'#ffc80d'.'#eee3af'.'#b5e61d'.'#99d9ea'.'#7092be'.'#c8bfe7',].}}function initControls() {
    controls = new THREE.TrackballControls(camera);

    controls.rotateSpeed = 0.2;// Rotation speed
    controls.zoomSpeed = 0.2;// Zoom speed
    controls.panSpeed = 0.1;// 平controls
    controls.staticMoving = false;// Static movement, true, no inertia
    controls.dynamicDampingFactor = 0.2;// The smaller the damping coefficient, the larger the slip

    controls.minDistance = near; // Minimum viewing Angle
    controls.maxDistance = far;// The maximum Angle is Infinity
}

/* Window changes trigger */
function onWindowResize() {
    camera.aspect = window.innerWidth / window.innerHeight;
    camera.updateProjectionMatrix();
    renderer.setSize(window.innerWidth, window.innerHeight);
}
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Render loop

With all the preparation done, it’s time to render

function animation() {
    renderer.render(scene, camera);
    requestAnimationFrame(animation);
    stats.update();
    controls.update();
    update()
}

/* Data update */
function update() {
	// All parameters are updated
}

function threeStart() {
    // Initialize the renderer
    initRenderer()
    // Initialize the scene
    initScene();
    // Initialize the camera
    initCamera();
    // Initialize the light
    initLight();
    // Initialize the object
    initObject();

    // Initialize the ball placement
    initControls();
    // Initialize the GUI interface
    initGUI()
    // Initialize performance monitoring
    initStats()
    // Initialize the color picker
    initColorPicker()

    // Render loop
    animation();
    /* Listen on events */
    window.addEventListener('resize', onWindowResize, false);
}
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Final reality effect Codepen sample code

conclusion

In this section, we mainly talk about the following contents:

Refactoring the project code
Threejs model loading process
Load VTK model

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ThreeJs Starter 22- Load VTK model

Reconstruction project

Threejs model loading process

Load VTK model

HTML page

Initialize the renderer

Initialization Scenario

Initializing the camera

Initialize light

Initialize object

Creating the base Material

Loader loads the VTK model

Initialize various controls

Render loop

conclusion

ThreeJs Starter 22- Load VTK model

Reconstruction project

Threejs model loading process

Load VTK model

HTML page

Initialize the renderer

Initialization Scenario

Initializing the camera

Initialize light

Initialize object

Creating the base Material

Loader loads the VTK model

Initialize various controls

Render loop

conclusion

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