摄像机的LookAt

作者: Codifier | 来源:发表于2019-11-08 15:41 被阅读0次

摄像机的LookAt
关于LookAt的总结
QT+OpenGL四之相机的移动和旋转
unity 类似Lookat缓慢的转动摄像机朝向某个物体
角色头上血条显示控制代码
Unity解决LookAt乱动的问题
C4D完全自学实践指南（六 -Ⅰ ）：摄像机
2018-01-03
three.js camera lookat
Blender视图渲染知识

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Camera Look At</title>
    <script src="../../three-part/threejs/three.js"></script>
    <script src="../../three-part/utils/stats.min.js"></script>
    <script src="../../three-part/utils/dat.gui.min.js"></script>
    <script src="../controls/TrackballControls.js"></script>
    <script src="../util/util.js"></script>
    <style>
        body {
            margin: 0;
            overflow: hidden;
        }
    </style>
</head>
<body>
<div id="container"></div>
<script type="text/javascript">
    init();
    function init() {
        // show FPS
        let stats = initStats();
        // resize
        window.addEventListener('resize', onResize, false);

        let scene = new THREE.Scene();
        let camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.1, 1000);
        camera.position.x = 120;
        camera.position.y = 60;
        camera.position.z = 180;

        let renderer = new THREE.WebGLRenderer();
        renderer.setClearColor(new THREE.Color(0x000000));
        renderer.setSize(window.innerWidth, window.innerHeight);
        document.getElementById("container").appendChild(renderer.domElement);

        // init trackball control
        let trackballControls = initTrackballControls(camera, renderer);
        let clock = new THREE.Clock();

        // create a plane
        let planeGeometry = new THREE.PlaneGeometry(180, 180);
        let planeMaterial = new THREE.MeshLambertMaterial({color: 0xffffff});
        let plane = new THREE.Mesh(planeGeometry, planeMaterial);
        plane.rotation.x = -0.5 * Math.PI;
        scene.add(plane);

        let cubeGeometry = new THREE.BoxGeometry(4, 4, 4);

        for (let j = 0; j < (planeGeometry.parameters.height / 5); j++) {
            for (let i = 0; i < planeGeometry.parameters.width / 5; i++) {
                let rnd = Math.random() * 0.75 + 0.25;
                let cubeMaterial = new THREE.MeshLambertMaterial();
                cubeMaterial.color = new THREE.Color(rnd, 0, 0);
                let cube = new THREE.Mesh(cubeGeometry, cubeMaterial);

                cube.position.z = -((planeGeometry.parameters.height) / 2) + 2 + (j * 5);
                cube.position.x = -((planeGeometry.parameters.width) / 2) + 2 + (i * 5);
                cube.position.y = 2;

                scene.add(cube);
            }
        }

        let mesh = new THREE.Mesh(new THREE.SphereGeometry(2), new THREE.MeshLambertMaterial({color:0x00ff00}));
        scene.add(mesh);

        // add directional light
        let directionalLight = new THREE.DirectionalLight(0xffffff, 0.7);
        directionalLight.position.set(-20, 40, 60);
        scene.add(directionalLight);


        // add ambient light
        let ambientLight = new THREE.AmbientLight(0x292929);
        scene.add(ambientLight);

        // attributes which can be modified in GUI
        const controls = {
            "currentCameraType" : "perspective",
            "switchCamera" : function(){
                if (camera instanceof THREE.PerspectiveCamera) {
                    camera = new THREE.OrthographicCamera(window.innerWidth / -16, window.innerWidth / 16, window.innerHeight / 16, window.innerHeight / -16, -200, 500);
                    camera.position.x = 120;
                    camera.position.y = 60;
                    camera.position.z = 180;
                    camera.lookAt(scene.position);
                    trackballControls = initTrackballControls(camera, renderer);
                    this.currentCameraType = "Orthographic";
                } else {
                    camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.1, 1000);
                    camera.position.x = 120;
                    camera.position.y = 60;
                    camera.position.z = 180;
                    camera.lookAt(scene.position);
                    trackballControls = initTrackballControls(camera, renderer);
                    this.currentCameraType = "Perspective";
                }
            }
        };
        // init GUI
        initGUI();

        let step = 0;
        renderScene();

        function initGUI(){
            let gui = new dat.GUI();
            gui.add(controls, 'switchCamera');
            gui.add(controls, 'currentCameraType').listen();
        }

        function onResize() {
            camera.aspect = window.innerWidth / window.innerHeight;
            camera.updateProjectionMatrix();
            renderer.setSize(window.innerWidth, window.innerHeight);
![2019-11-08_153854.png](https://img.haomeiwen.com/i15717141/d2c957e52441a2a2.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)
        }

        function renderScene(){
            trackballControls.update(clock.getDelta());
            stats.update();
            step += 0.02;
            // update the position of camera look at
            if (camera instanceof THREE.Camera) {
                let x = 10 + ( 100 * (Math.sin(step)));
                camera.lookAt(new THREE.Vector3(x, 10, 0));
                mesh.position.copy(new THREE.Vector3(x, 10, 0));
            }
            requestAnimationFrame(renderScene);
            renderer.render(scene, camera);
        }
    }
</script>
</body>
</html>

运行结果：