Unity 如何手动计算网格的法线
时间: 2024-03-28 10:41:56 浏览: 13
手动计算网格的法线可以通过以下步骤实现:
1. 获取网格的顶点和三角形列表。可以使用 `Mesh.vertices` 和 `Mesh.triangles` 属性来获取它们。
```csharp
Vector3[] vertices = mesh.vertices;
int[] triangles = mesh.triangles;
```
2. 为每个顶点计算法线。遍历三角形列表,对于每个三角形,计算它的面法线,并将其添加到其三个顶点的法线总和中。
```csharp
Vector3[] normals = new Vector3[vertices.Length];
for (int i = 0; i < triangles.Length; i += 3) {
int i1 = triangles[i];
int i2 = triangles[i + 1];
int i3 = triangles[i + 2];
Vector3 v1 = vertices[i1];
Vector3 v2 = vertices[i2];
Vector3 v3 = vertices[i3];
Vector3 normal = Vector3.Cross(v2 - v1, v3 - v1).normalized;
normals[i1] += normal;
normals[i2] += normal;
normals[i3] += normal;
}
```
3. 归一化每个顶点的法线。对于每个顶点,将其法线向量除以其长度,以使其长度为1。
```csharp
for (int i = 0; i < normals.Length; i++) {
normals[i].Normalize();
}
```
4. 将计算出的法线设置为网格的法线。使用 `Mesh.normals` 属性将计算出的法线向量数组分配给网格。
```csharp
mesh.normals = normals;
```
完整的代码示例:
```csharp
void CalculateNormals(Mesh mesh) {
Vector3[] vertices = mesh.vertices;
int[] triangles = mesh.triangles;
Vector3[] normals = new Vector3[vertices.Length];
for (int i = 0; i < triangles.Length; i += 3) {
int i1 = triangles[i];
int i2 = triangles[i + 1];
int i3 = triangles[i + 2];
Vector3 v1 = vertices[i1];
Vector3 v2 = vertices[i2];
Vector3 v3 = vertices[i3];
Vector3 normal = Vector3.Cross(v2 - v1, v3 - v1).normalized;
normals[i1] += normal;
normals[i2] += normal;
normals[i3] += normal;
}
for (int i = 0; i < normals.Length; i++) {
normals[i].Normalize();
}
mesh.normals = normals;
}
```