【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: 0 ~ 5
                indices[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: 0 ~ 5
                indices[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: 0 ~ 5
                indices[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：

声明：本文转自【Unity3D】绘制物体表面三角形网格