react+three.js 设置背景颜色或图片

介绍两种方法来实现 在react项目中为three.js生成的内容设置背景

1.通过css设置canvas 的背景

new THREE.WebGLRenderer({canvas, alpha: true, antialias: true })这里创建渲染器的方法第一个参数canvas 如果不传递的话，会在指定的 this.mount中自动生成一个canvas 如果指定了canvas会在指定的canvas 中渲染内容。在这里我们把要渲染的指定为 this.refs.pic并且要设置 透明
alpha : true

在这里做一个提示，两个方法 写相对路径都无用，而且背景写内联样式才有效果
html

  render() {
        return (
            <div
                id= "canvas"
                style={{ width: '600px', height: '600px' }}
                ref={(mount) => { this.mount = mount }}
            >
              <canvas 
                ref = "pic" 
                className="pic"
                style={{ background: 'linear-gradient(to right, #4590ad, #03163a )'}}  //用渐变做背景
                // style = {{background: 'url(https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1565586852696&di=10d15429d474cfbc812fa8a8430208ea&imgtype=0&src=http%3A%2F%2Fimg4q.duitang.com%2Fuploads%2Fitem%2F201305%2F08%2F20130508002211_CuPYn.jpeg)', backgroundSize: 'cover'}}//用 图片做背景
              ></canvas>
            </div>
        );
    } 

js

        const canvas = this.refs.pic
        const scene =  new THREE.Scene()
        const camera = new THREE.PerspectiveCamera( 75, this.mount.clientWidth / this.mount.clientHeight, 0.1, 1000 );
        const renderer = new THREE.WebGLRenderer({canvas, alpha: true, antialias: true });
        renderer.autoClearColor = false;
        this.scene = scene
        this.camera = camera
        this.renderer = renderer
        renderer.setSize(this.mount.clientWidth, this.mount.clientHeight );
        this.mount.appendChild( renderer.domElement );
        camera.position.set(0, 50, 0);
        camera.up.set(0, 0, 1);
        camera.lookAt(0, 0, 0);
        //this.createLight()
        //this.createStars()
        //this.animate();

2.可以用three.js自带的方法来写

这里不需要指定canvas 。自动生成后设置sence背景就可以了，但是背景可能因为尺寸原因而变形
如果想改变形状可以参考three.js的官网或者 教程

html

            <div
                id= "canvas"
                style={{ width: '600px', height: '600px' }}
                ref={(mount) => { this.mount = mount }}
            >
            </div>

js

componentDidMount() {
        console.log(this.refs)
        this.init()
    }
    
    init = () => {
        const scene =  new THREE.Scene()
        const camera = new THREE.PerspectiveCamera( 75, this.mount.clientWidth / this.mount.clientHeight, 0.1, 1000 );
        const renderer = new THREE.WebGLRenderer({antialias: true });
        renderer.autoClearColor = false;
        this.scene = scene
        this.camera = camera
        this.renderer = renderer
        renderer.setSize(this.mount.clientWidth, this.mount.clientHeight );
        this.mount.appendChild( renderer.domElement );
        camera.position.set(0, 50, 0);
        camera.up.set(0, 0, 1);
        camera.lookAt(0, 0, 0);
        const loader = new THREE.TextureLoader();
        const bgTexture = loader.load('../../assets/bg.jpg');
        scene.background = bgTexture;
    }