Three.js:将法线从本地空间转换为世界空间 | 将法线从本地空间转换为世界空间

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问题描述

我有一个THREE.PlaneGeometry和ComputeFaceNormals().我使用此几何形状创建了两个网格，并对其应用了不同的旋转.我想计算相机和两个网格中心面法线之间的两个角度.应该是:

I have a THREE.PlaneGeometry, with ComputeFaceNormals(). I create two meshes using this geometry, with different rotations applied to them. I want to compute the two angles between the camera and the two meshes central face normal. It should be :

vLocalCamera = vCamera.position - mesh1.position;

mesh1.normal() . vLocalCamera = cos(angle);

问题是我不知道如何使用three.js API在世界坐标中(通过几何和网格旋转)获得网格法线

The problem is that I don't know how to get the mesh normal in world coordinate (from geometry and mesh rotation) with three.js API

推荐答案

如果要将面或顶点法线normal从局部空间转换为世界空间，则可以这样做:

If you want to convert a face or vertex normal, normal, from local space to world space, you do it like so:

var normalMatrix = new THREE.Matrix3(); // create once and reuse
var worldNormal = new THREE.Vector3(); // create once and reuse

...

normalMatrix.getNormalMatrix( object.matrixWorld );

worldNormal.copy( normal ).applyMatrix3( normalMatrix ).normalize();

three.js r.107

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