example/多canvas/mulCanvas.html

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <script src="../js/threejs/three.min.js"></script>
    <script src="../js/controls/OrbitControls.js"></script>
    <title>多画布-网格</title>
</head>
<style>
    #canvas1,
    #canvas2 {
        position: relative;
        width: 300px;
        height: 200px;
        border: 1px solid red;
        float: left;
    }
</style>

<body>

    <canvas id="canvas1"></canvas>
    <canvas id="canvas2"></canvas>
    <script>
        var scene, renderer;
        var WIDTH, HEIGHT;
        var views = [];

        //  创建渲染器
        function initRender() {
            WIDTH = 300; //window.innerWidth;
            HEIGHT = 200; //window.innerHeight;
            renderer = new THREE.WebGLRenderer({
                antialias: true,
            });
            renderer.setSize(WIDTH, HEIGHT);
            renderer.setPixelRatio(window.devicePixelRatio);
            document.body.appendChild(renderer.domElement);
        }
        //  创建场景
        function initScene() {
            scene = new THREE.Scene();
            scene.background = new THREE.Color(0xeeeeee);
        }
        //  创建相机
        function initCamera() {
            var canvas1 = document.getElementById('canvas1');
            var canvas2 = document.getElementById('canvas2');
            var w = 300,
                h = 200;

            var fullWidth = w * 2;
            var fullHeight = h * 1;
            //  创建相机并渲染后绘制到canvas 并 加入到数组
            views.push(new View(canvas1, fullWidth, fullHeight, w * 0, h * 0, w, h));
            views.push(new View(canvas2, fullWidth, fullHeight, w * 1, h * 0, w, h));
        }
        //  创建灯光
        function initLight() {
            var light = new THREE.DirectionalLight(0xffffff);
            light.position.set(0, 0, 1).normalize();
            scene.add(light);

            var light = new THREE.AmbientLight(0x404040); // 环境光
            scene.add(light);
        }
        //  创建网格对象
        function initObject() {
            var geometry = new THREE.BoxGeometry(10, 10, 10);
            var material = new THREE.MeshLambertMaterial({
                color: 0x00ff00
            });
            var cube = new THREE.Mesh(geometry, material);
            scene.add(cube);
        }
        //  入口函数
        function initThree() {
            initRender();
            initScene();
            initCamera();
            initLight();
            initObject();
            animation();
        }
        //  循环
        function animation() {
            requestAnimationFrame(animation);
            for (var i = 0; i < views.length; ++i) {

                views[i].render();

            }
        }
        /*
        *	canvas：表示要在上面显示内容的div的id名字。如canvas1、canvas2。
            fullWidth：视口的宽度
            fullHeight：视口的高度
            viewX：我们可以选择只显示视口的某一部分，viewX表示从视口x坐标的哪里开始显示。
            viewY：如上，viewY表示从视口Y坐标的哪里开始显示。
            viewWidth：只显示视口中某一部分的宽度
            viewHeight：只显示视口中某一部分的高度。
        */
        function View(canvas, fullWidth, fullHeight, viewX, viewY, viewWidth, viewHeight) {
            //  这里需要注意的是 这里乘以的屏幕比例必须与renderer设置的一致。否则canvas上的图与相机视口图不一致
            canvas.width = viewWidth * window.devicePixelRatio;
            canvas.height = viewHeight * window.devicePixelRatio;

            var context = canvas.getContext('2d');

            var camera = new THREE.PerspectiveCamera(20, viewWidth / viewHeight, 1, 10000);
            var controls = new THREE.OrbitControls(camera);
            /*
            fullWidth：整个视图（口）的宽度，也可以理解为相机的宽度。
            fullHeight：整个视图（口）的高度，也可以理解为相机的高度。
            x：视图的x轴偏移位置，及要显示的部分相对于左上角的偏移。
            y：视图的y轴偏移位置
            width：子视图的宽度，只有这个宽度才被显示
            height：子视图的高度，只有这个高度才被显示
            */
            camera.setViewOffset(fullWidth, fullHeight, viewX, viewY, viewWidth, viewHeight);
            camera.position.z = 100;

            this.render = function () {
                camera.lookAt(scene.position);
                renderer.render(scene, camera);
                controls.update();
                context.drawImage(renderer.domElement, 0, 0);
            };

        }

        initThree();
    </script>
</body>

</html>