如何在网格上指定顶点法线？

Question

我导入了一个网格，并且已经为它计算了顶点法线。我想使用我的法线而不是为几何对象调用computeVertexNormals（）。现在我有

var geometry = THREE.Geometry();
// fill in vertex, face and texture
// ...
// compute normals
geometry.computeFaceNormals();
geometry.computeVertexNormals();  // <-- Would like to replace this

文档中有一个使用缓冲区属性但没有示例的引用。 http://threejs.org/docs/index.html?q=vertex#Reference/Core/BufferAttribute

有谁知道怎么做？

感谢，

约翰

Answer 1

对于THREE.Geometry对象，顶点法线与面存储在一起。如果NormalList包含顶点的法线向量，则此循环将执行此操作。

/*
 * Add the normals. They are added to the face array
 */
for ( f = 0, fl = geometry.faces.length; f < fl; f ++ ) {


var face = geometry.faces[ f ];

var ndx = face.a;           
var normal = new THREE.Vector3();
normal.x = NormalList[ndx].x;
normal.y = NormalList[ndx].y;
normal.z = NormalList[ndx].z;
face.vertexNormals[ 0 ] = normal;

ndx = face.b;  
normal = new THREE.Vector3();
normal.x = NormalList[ndx].x;
normal.y = NormalList[ndx].y;
normal.z = NormalList[ndx].z;
face.vertexNormals[ 1 ] = normal;

ndx = face.c;
normal = new THREE.Vector3();
normal.x = NormalList[ndx].x;
normal.y = NormalList[ndx].y;
normal.z = NormalList[ndx].z;
face.vertexNormals[ 2 ] = normal;


}