自定義相機控制 - 基於滑鼠的滑動

Created: November-22, 2018

這是一個自定義相機控制器的示例。這將在客戶端視窗中讀取滑鼠的位置，然後將相機滑動，就像它在視窗上跟隨滑鼠一樣。

index.html

<html>
    <head>
        <title>Three.js Custom Mouse Camera Control Example</title>
        <script src="/javascripts/three.js"></script>
    </head>
    <body>
        <script src="javascripts/scene.js"></script>
    </body>
</html>

scene.js

var scene, renderer, camera;
var cube;
var cameraCenter = new THREE.Vector3();
var cameraHorzLimit = 50;
var cameraVertLimit = 50;
var mouse = new THREE.Vector2();

init();
animate();

function init()
{
    renderer = new THREE.WebGLRenderer( {antialias:true} );
    var width = window.innerWidth;
    var height = window.innerHeight;
    renderer.setSize (width, height);
    document.body.appendChild (renderer.domElement);
  
    scene = new THREE.Scene();
    
    var cubeGeometry = new THREE.BoxGeometry (10,10,10);
    var cubeMaterial = new THREE.MeshBasicMaterial ({color: 0x1ec876});
    cube = new THREE.Mesh (cubeGeometry, cubeMaterial);

    cube.position.set (0, 0, 0);
    scene.add (cube);

    camera = new THREE.PerspectiveCamera (45, width/height, 1, 10000);
    camera.position.y = 160;
    camera.position.z = 400;
    camera.lookAt (new THREE.Vector3(0,0,0));
    cameraCenter.x = camera.position.x;
    cameraCenter.y = camera.position.y;

    //set up mouse stuff
    document.addEventListener('mousemove', onDocumentMouseMove, false);
    window.addEventListener('resize', onWindowResize, false);
    
    var gridXZ = new THREE.GridHelper(100, 10);
    gridXZ.setColors( new THREE.Color(0xff0000), new THREE.Color(0xffffff) );
    scene.add(gridXZ);
}

function onWindowResize ()
{
    camera.aspect = window.innerWidth / window.innerHeight;
    camera.updateProjectionMatrix();
    renderer.setSize (window.innerWidth, window.innerHeight);
}

function animate()
{   
    updateCamera();
    requestAnimationFrame ( animate );  
    renderer.render (scene, camera);
}

function updateCamera() {
    //offset the camera x/y based on the mouse's position in the window
    camera.position.x = cameraCenter.x + (cameraHorzLimit * mouse.x);
    camera.position.y = cameraCenter.y + (cameraVertLimit * mouse.y);
}

function onDocumentMouseMove(event) {
    event.preventDefault();
    mouse.x = (event.clientX / window.innerWidth) * 2 - 1;
    mouse.y = -(event.clientY / window.innerHeight) * 2 + 1;
}

function onWindowResize() {
    camera.aspect = window.innerWidth / window.innerHeight;
    camera.updateProjectionMatrix();
    renderer.setSize(window.innerWidth, window.innerHeight);
}

如你所見，這裡我們只是在渲染的 animate 階段更新 Camera 位置，就像場景中的任何物件一樣。在這種情況下，我們只是將相機重新定位在偏離其原始 X 和 Y 座標的點上。這可能很容易就是 X 和 Z 座標，或者沿著路徑的點，或完全不同的東西，甚至根本不與滑鼠的位置相關。