【Unity3D】绘制物体表面三角形网格

1 仅绘制三角形网格

1）创建游戏对象

创建一个空对象，重命名为 Grid，并在其下添加需要绘制网格的对象，如下：

场景显示如下：

2）添加脚本组件

GridController.cs

using System;
using UnityEngine;public class GridController : MonoBehaviour {private void Start () {ForAllChildren(transform, RebuildMesh);}private void RebuildMesh(Transform transform) {MeshFilter meshFilter = transform.GetComponent<MeshFilter>();if (meshFilter != null && meshFilter.mesh != null) {int[] indices = MakeIndices(meshFilter.mesh.triangles);meshFilter.mesh.SetIndices(indices, MeshTopology.Lines, 0);}}private int[] MakeIndices(int[] triangles) {int[] indices = new int[2 * triangles.Length];for( int i = 0; i < triangles.Length; i += 3 ) {for (int j = 0; j < 6; j++) {// 每个三角形转换为3条线段, 每个顶点使用2次, 对应的顶点序列是: 0, 1, 1, 2, 2, 0, 通式: (j + 1) % 6 / 2, j 的范围: 1 ~ 5indices[2 * i + j] = triangles[i + (j + 1) % 6 / 2];}}return indices;}private void ForAllChildren(Transform transform, Action<Transform> action) {action.Invoke(transform);for (int i = 0; i < transform.childCount; i++) {ForAllChildren(transform.GetChild(i), action);}}
}

说明： GridController 脚本组件挂在 Grid 对象上。

运行效果：

3）给网格添加新材质

GridController.cs

using System;
using UnityEngine;public class GridController : MonoBehaviour {public Material material;private void Start () {ForAllChildren(transform, RebuildMesh);}private void RebuildMesh(Transform transform) {MeshFilter meshFilter = transform.GetComponent<MeshFilter>();MeshRenderer meshRenderer = transform.GetComponent<MeshRenderer>();if (meshFilter != null && meshFilter.mesh != null && meshRenderer != null) {meshRenderer.material = material;int[] indices = MakeIndices(meshFilter.mesh.triangles);meshFilter.mesh.SetIndices(indices, MeshTopology.Lines, 0);}}private int[] MakeIndices(int[] triangles) {int[] indices = new int[2 * triangles.Length];for( int i = 0; i < triangles.Length; i += 3 ) {for (int j = 0; j < 6; j++) {// 每个三角形转换为3条线段, 每个顶点使用2次, 对应的顶点序列是: 0, 1, 1, 2, 2, 0, 通式: (j + 1) % 6 / 2, j 的范围: 1 ~ 5indices[2 * i + j] = triangles[i + (j + 1) % 6 / 2];}}return indices;}private void ForAllChildren(Transform transform, Action<Transform> action) {action.Invoke(transform);for (int i = 0; i < transform.childCount; i++) {ForAllChildren(transform.GetChild(i), action);}}
}

运行效果：

2 绘制表面和三角形网格

场景中所有对象同第 1 节，脚本组件如下：

GridController.cs

using System;
using UnityEngine;
using UnityEngine.Rendering;public class GridController : MonoBehaviour {public Material material;private void Start () {ForAllChildren(transform, RebuildMesh);}private void RebuildMesh(Transform transform) {MeshFilter meshFilter = transform.GetComponent<MeshFilter>();MeshRenderer meshRenderer = transform.GetComponent<MeshRenderer>();if (meshFilter != null && meshFilter.mesh != null && meshRenderer != null) {InitMaterials(meshRenderer);int[] indices = MakeIndices(meshFilter.mesh.triangles);InitSubMesh(meshFilter.mesh, indices, indices.Length / 3);}}private void InitMaterials(MeshRenderer meshRenderer) {Material[] materials = new Material[meshRenderer.materials.Length + 1];meshRenderer.materials.CopyTo(materials, 0);materials[materials.Length - 1] = material;meshRenderer.materials = materials;}private void InitSubMesh(Mesh mesh, int[] indices, int divide) {mesh.SetIndexBufferParams(indices.Length, IndexFormat.UInt32);mesh.SetIndexBufferData(indices, 0, 0, indices.Length);mesh.subMeshCount = 2; // 设置2个子网格// 第一部分绘制三角形内部SubMeshDescriptor subMeshDescriptor1 = new SubMeshDescriptor(0, divide, MeshTopology.Triangles);mesh.SetSubMesh(0, subMeshDescriptor1);// 第二部分绘制线段SubMeshDescriptor subMeshDescriptor2 = new SubMeshDescriptor(divide, indices.Length - divide, MeshTopology.Lines);mesh.SetSubMesh(1, subMeshDescriptor2);}private int[] MakeIndices(int[] triangles) {int[] indices = new int[3 * triangles.Length];triangles.CopyTo(indices, 0);for( int i = 0; i < triangles.Length; i += 3 ) {for (int j = 0; j < 6; j++) {// 每个三角形转换为3条线段, 每个顶点使用2次, 对应的顶点序列是: 0, 1, 1, 2, 2, 0, 通式: (j + 1) % 6 / 2, j 的范围: 1 ~ 5indices[triangles.Length + 2 * i + j] = triangles[i + (j + 1) % 6 / 2];}}return indices;}private void ForAllChildren(Transform transform, Action<Transform> action) {action.Invoke(transform);for (int i = 0; i < transform.childCount; i++) {ForAllChildren(transform.GetChild(i), action);}}
}

运行效果：