由于我是 3D 世界和三个 JS 世界的新手,所以我了解大部分内容,但在涉及矩阵时总是感到困惑。
我想做的是,我想将一个小对象拖到其他对象之上,并且小对象应该面向主要对象的相同方向(一个例子就像在墙上挂一个挂钟)。
为此,我首先尝试在旋转立方体的顶部放置一个轴助手,并应用简单的逻辑,一个相交点将给出放置小物体的位置,相交的物体面法线将为小物体提供方向 lookAt .我做了并发现成功但不合适。
然后我做了一些计算并搜索了一些代码来计算相同的东西,我现在成功了。但不理解背后的整个逻辑,为什么我们这样做。
this.normalMatrix.getNormalMatrix(intersects[i].object.matrixWorld);
this.worldNormal.copy(intersects[i].face.normal).applyMatrix3(this.normalMatrix).normalize();
this.object.position.addVectors(intersects[i].point, this.worldNormal);
this.lookAtVec.addVectors(this.object.position,this.worldNormal.multiplyScalar(15));
this.object.lookAt(this.lookAtVec);
一个人实际上创造了一堵墙,并在上面放了一个小物体。他改变了这一行
this.object.position.addVectors(intersects[i].point, this.worldNormal);
到
this.object.position.copy(intersects[i].point);
这对他有用,但同样的事情对我的轴助手不起作用。
最佳答案
只是你如何做的一个选择。查看 onMouseMove()
函数的结尾:
var scene = new THREE.Scene();
var camera = new THREE.PerspectiveCamera(60, window.innerWidth / window.innerHeight, 1, 1000);
camera.position.set(-3, 5, 8);
camera.lookAt(scene.position);
var renderer = new THREE.WebGLRenderer({
antialias: true
});
renderer.setSize(window.innerWidth, window.innerHeight);
renderer.setClearColor(0x404040);
document.body.appendChild(renderer.domElement);
var controls = new THREE.OrbitControls(camera, renderer.domElement);
var light = new THREE.DirectionalLight(0xffffff, 0.5);
light.position.setScalar(10);
scene.add(light);
scene.add(new THREE.AmbientLight(0xffffff, 0.5));
var walls = [];
makeWall(Math.PI * 0.5);
makeWall(0);
makeWall(Math.PI * -0.5);
var clockGeom = new THREE.BoxBufferGeometry(1, 1, 0.1);
clockGeom.translate(0, 0, 0.05);
var clockMat = new THREE.MeshBasicMaterial({
color: "orange"
});
var clock = new THREE.Mesh(clockGeom, clockMat);
scene.add(clock);
var raycaster = new THREE.Raycaster();
var mouse = new THREE.Vector2();
var intersects = [];
var lookAt = new THREE.Vector3();
renderer.domElement.addEventListener("mousemove", onMouseMove, false);
function onMouseMove(event) {
mouse.x = (event.clientX / window.innerWidth) * 2 - 1;
mouse.y = -(event.clientY / window.innerHeight) * 2 + 1;
raycaster.setFromCamera(mouse, camera);
intersects = raycaster.intersectObjects(walls);
if (intersects.length === 0) return;
clock.position.copy(intersects[0].point);
clock.lookAt(lookAt.copy(intersects[0].point).add(intersects[0].face.normal));
}
render();
function render() {
requestAnimationFrame(render);
renderer.render(scene, camera);
}
function makeWall(rotY, color) {
let geom = new THREE.BoxBufferGeometry(8, 8, 0.1);
geom.translate(0, 0, -4);
geom.rotateY(rotY);
let mat = new THREE.MeshLambertMaterial({
color: Math.random() * 0x777777 + 0x777777
});
let wall = new THREE.Mesh(geom, mat);
scene.add(wall);
walls.push(wall);
}
body {
overflow: hidden;
margin: 0;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/94/three.min.js"></script>
<script src="https://threejs.org/examples/js/controls/OrbitControls.js"></script>
关于javascript - 三个JS中这段代码片段的含义,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/51230611/