您好，感谢您阅读这个问题:

我正在学习 Threejs，目前我有一个奇怪的困难:

我已经学会了如何使用加载器以纯 HTML/JAVASCRIPT 加载格式为 NRRD 的本地文件:这里是 repo:https://github.com/YoneMoreno/LoadNRRDInThreeJSExample

作为它的外观示例:

但是，我想将前面的示例与 React 集成。

我研究了如何使用这个 SO 线程关联 React 和 Three: Rendering three.js element in React?

现在我的代码是这样的:

/*global THREE */

import React from 'react';

class LoadNRRD extends React.Component {

    constructor(props) {
        super(props)

        this.start = this.start.bind(this)
        this.stop = this.stop.bind(this)
        this.animate = this.animate.bind(this)
    }

    componentDidMount() {
        const width = this.mount.clientWidth
        const height = this.mount.clientHeight

        const scene = new THREE.Scene()
        const camera = new THREE.PerspectiveCamera(
            75,
            width / height,
            0.1,
            1000
        )

        var loader = new THREE.NRRDLoader();
        loader.load("models/columnasegmentado01.nrrd", function (volume) {
            var sliceZ;


            //z plane

            var indexZ = 0;
            sliceZ = volume.extractSlice('z', Math.floor(volume.RASDimensions[2] / 4))
            console.log(sliceZ);
            scene.add(sliceZ.mesh);

        });

        const renderer = new THREE.WebGLRenderer({antialias: true})
        renderer.setPixelRatio(window.devicePixelRatio);
        renderer.setSize(width, height);


        renderer.setClearColor('#000000')


        this.scene = scene
        this.camera = camera
        this.renderer = renderer

        let controls = new THREE.TrackballControls(camera, renderer.domElement);
        controls.rotateSpeed = 0;
        controls.zoomSpeed = 5;
        controls.panSpeed = 2;
        controls.noZoom = false;
        controls.noPan = false;
        controls.staticMoving = true;
        controls.dynamicDampingFactor = 0.3;


        this.mount.appendChild(this.renderer.domElement)
        this.start()
    }

    componentWillUnmount() {
        this.stop()
        this.mount.removeChild(this.renderer.domElement)
    }

    start() {
        if (!this.frameId) {
            this.frameId = requestAnimationFrame(this.animate)
        }
    }

    stop() {
        cancelAnimationFrame(this.frameId)
    }

    animate() {


        this.renderScene()
        this.frameId = window.requestAnimationFrame(this.animate)
    }

    renderScene() {
        this.renderer.render(this.scene, this.camera)
    }

    render() {
        return (
            <div
                style={{width: '2000px', height: '2000px'}}
                ref={(mount) => {
                    this.mount = mount
                }}
            />
        )
    }
}

export default LoadNRRD;

我不明白的部分是:为什么它显示 Canvas 但里面没有模型？

我已经检查加载程序是否运行良好并且模型是否就位，因为我们可以在控制台日志中看到它:

THREE.VolumeSlice
axis:"z"
canvas:canvas
canvasBuffer:canvas
... more properties ...

你能帮帮我吗？我错过了一些步骤吗？您以前遇到过这个问题吗？您如何尝试调试这种情况？

请注意，在分支 ThreeIntegrate 中是我正在编写的代码:https://github.com/PrototipoAtlas/Prototipo

如果您有任何意见或建议，请告诉我 ? ?

编辑: 谢谢@Jim Tang 的建议。我已经安装了三个 Chrome 扩展程序，并且在全局变量 window.scene 中设置场景后它给出的输出如下所示: https://github.com/jeromeetienne/threejs-inspector/issues/11

结果是:

我尝试使用独立的纯 HTML/JS 示例，它的模型如下:

那么关键问题是:为什么模型与场景没有关联？‽‽

我又试了一次，看起来模型确实已加载，但是当我尝试更改 iot 的颜色时，在控制台中，甚至单击它时显示:

THREE.MeshBasicMaterial: .shading has been removed. Use the boolean .flatShading instead.

我认为，解决方案可能是发现缺失的部分。如果我们再次看到有效的示例，我们有三个元素:

我怀疑这三个元素可能是添加到 DOM 中的元素:

        document.body.appendChild(container);
        container.appendChild(renderer.domElement);
...more code...
        container.appendChild(stats.dom);

在不显示模型的代码中，附加的是:

this.mount.appendChild(this.renderer.domElement);
this.mount.removeChild(this.renderer.domElement)

即使删除了附加的不常见元素，统计信息，纯 HTML/JS 示例仍然有效并显示了三个元素!!

我发现缺少的元素是相机，因为如果我们看到工作示例，对象有 fov、near、far 等:

所以我尝试在我们正在讨论的代码中将相机添加到场景中:

const scene = new THREE.Scene();
        const camera = new THREE.PerspectiveCamera(
            75,
            width / height,
            0.1,
            1000
        );


        scene.add(camera);

它提供了一个巨大的堆栈跟踪:

    TypeError: Cannot read property 'getExtension' of null
    get
    http://localhost:3001/build/three.js:20112:22
    initGLContext
    http://localhost:3001/build/three.js:21116:15
    new WebGLRenderer
    http://localhost:3001/build/three.js:21161:3
    LoadNRRD.componentDidMount
    http://localhost:3001/static/js/bundle.js:62599:28
      62596 |     scene.add(sliceZ.mesh);
      62597 | });
      62598 | 
    > 62599 | var renderer = new THREE.WebGLRenderer({ antialias: true });
            |                ^  62600 | renderer.setPixelRatio(window.devicePixelRatio);
      62601 | renderer.setSize(width, height);
      62602 | 
    View source
    ▶ 17 stack frames were collapsed.
    ./src/index.js
    C:/Users/YonePC/WebstormProjects/prototipo/src/index.js:22
      19 |     );
      20 | };
      21 | 
    > 22 | ReactDOM.render(
      23 |     <BrowserRouter>
      24 |         <App/>
      25 |     </BrowserRouter>
    View compiled
    ▶ 6 stack frames were collapsed.

TypeError: Cannot read property 'domElement' of undefined
LoadNRRD.componentWillUnmount
C:/Users/YonePC/WebstormProjects/prototipo/src/components/animals/LoadNRRD.js:73
  70 | 
  71 |    componentWillUnmount() {
  72 |        this.stop();
> 73 |        this.mount.removeChild(this.renderer.domElement)
  74 |    }
  75 | 
  76 |    start() {
View compiled
▶ 25 stack frames were collapsed.
./src/index.js
C:/Users/YonePC/WebstormProjects/prototipo/src/index.js:22
  19 |     );
  20 | };
  21 | 
> 22 | ReactDOM.render(
  23 |     <BrowserRouter>
  24 |         <App/>
  25 |     </BrowserRouter>
View compiled
▶ 6 stack frames were collapsed.

编辑2:

我又试了一次，我们看到了:

我们正在讨论的代码:

/*global THREE */

import React from 'react';

class LoadNRRD extends React.Component {

    constructor(props) {
        super(props);

        this.stop = this.stop.bind(this);
        this.start = this.start.bind(this);
        this.animate = this.animate.bind(this)
    }

    componentDidMount() {
        const width = this.mount.clientWidth;
        const height = this.mount.clientHeight;

        var scene = new THREE.Scene();
        var camera = new THREE.PerspectiveCamera(
            75,
            width / height,
            0.1,
            1000
        );


        scene.add(camera);

        const loader = new THREE.NRRDLoader();
        loader.load("models/columnasegmentado01.nrrd", function (volume) {
            let sliceZ;


            //z plane

            const indexZ = 0;
            sliceZ = volume.extractSlice('z', Math.floor(volume.RASDimensions[2] / 4));
            sliceZ.name = 'foo';
            console.log(sliceZ);
            scene.add(sliceZ.mesh);

        });

        var renderer = new THREE.WebGLRenderer({antialias: true});
        renderer.setPixelRatio(window.devicePixelRatio);
        renderer.setSize(width, height);


        renderer.setClearColor('#000000');


        this.scene = scene;
        window.scene = scene;
        this.camera = camera;
        this.renderer = renderer;

        let controls = new THREE.TrackballControls(camera, renderer.domElement);
        controls.rotateSpeed = 0;
        controls.zoomSpeed = 5;
        controls.panSpeed = 2;
        controls.noZoom = false;
        controls.noPan = false;
        controls.staticMoving = true;
        controls.dynamicDampingFactor = 0.3;


        this.mount.appendChild(this.renderer.domElement);
        this.start()
    }

    componentWillUnmount() {
        this.stop();
        this.mount.removeChild(this.renderer.domElement)
    }

    start() {
        if (!this.frameId) {
            this.frameId = requestAnimationFrame(this.animate)
        }
    }

    stop() {
        cancelAnimationFrame(this.frameId)
    }

    animate() {


        this.renderScene();
        this.frameId = window.requestAnimationFrame(this.animate)
    }

    renderScene() {
        this.renderer.render(this.scene, this.camera)
    }

    render() {
        return (
            <div
                style={{width: '2000px', height: '2000px'}}
                ref={(mount) => {
                    this.mount = mount
                }}
            />
        )
    }
}

export default LoadNRRD;

如您所见，我已将名称添加到 sliceZ，它显示在 Web 控制台上:

EDIT3:使用渲染器信息对象进行调试:

我们看到有一个几何体和一个纹理，并且渲染方法被调用了 217 次:

{render: {…}, memory: {…}, programs: Array(0), autoReset: false, reset: ƒ}
autoReset:false
memory:geometries:1 textures:1
__proto__:Object
programs:[WebGLProgram]
render:
calls:217
faces:434
frame:0
points:0
vertices:1302
__proto__:Object
reset:
ƒ resetInfo()
__proto__:
Object

我调试了一个工作示例，其中 React 与 Three 集成:

https://codepen.io/anon/pen/eMYxZw

然后在控制台上我们看到信息对象:

autoReset: false
​
memory: Object { geometries: 1, textures: 0 }
​
programs: Array [ {…} ]
​
render: Object { frame: 485, calls: 1, vertices: 36, … }
​
__proto__: Object { … }

所以我们看到调用次数为 1，可能是代码中的问题表明不断调用渲染器的渲染方法？

另外我上传了正在讨论的代码:

https://github.com/YoneMoreno/ThreeReactNRRDLoaderStandalone.git

你能帮帮我吗？

最佳答案

有一个google chrome扩展程序three.js inspector，您可以安装它并非常方便地检查场景层次结构。顺便说一句，如果它在一个元素内，它就无法找到你的三个对象。

关于javascript - 三个 : How could we insert a locally loaded mesh into the canvas being generated by Three to display it?，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/48967106/