TriangleNet下载如下：

TriangleNet

效果如下：

代码参考如下：

using System.Collections.Generic;
using UnityEngine;
using TriangleNet.Geometry;

public class TestTriangleNet : MonoBehaviour
{
	[SerializeField]
	Material material;
	void Start()
	{
		Vector3[] vs = new Vector3[625];
		for (int i = 0; i < vs.Length; i++)
		{
			vs[i] = new Vector3(i % 25, 0, i / 25);
		}

		Polygon poly = new();
		foreach (var v in vs)
		{
			poly.Add(new Vertex(v.x, v.z));
		}

		//设置外轮廓
		Vertex[] vertexOut = new Vertex[] { new(1, 10), new(3, 16), new(10, 19), new(16, 16), new(19, 10), new(16, 3), new(10, 1), new(3, 8) };
		poly.Add(new Contour(vertexOut), false);
		//设置洞洞1
		Vertex[] vertexIn01 = new Vertex[] { new(2, 10), new(4, 12), new(6, 10), new(4, 8) };
		poly.Add(new Contour(vertexIn01), true);
		//设置洞洞2
		Vertex[] vertexIn02 = new Vertex[] { new(12, 6), new(14, 8), new(16, 6), new(14, 4) };
		poly.Add(new Contour(vertexIn02), true);


		var options = new TriangleNet.Meshing.ConstraintOptions
		{
			SegmentSplitting = 1,
			ConformingDelaunay = false,
			Convex = false
		};
		//生成Triangle网格
		var triangleMesh = ExtensionMethods.Triangulate(poly, options);

		List<Vector3> listVert = new();
		foreach (Vertex v in triangleMesh.Vertices)
		{
			listVert.Add(new Vector3(v.X, 0, v.Y));
		}

		List<int> listTriangle = new();
		foreach (var tm in triangleMesh.Triangles)
		{
			listTriangle.Add(tm.GetVertexID(1));
			listTriangle.Add(tm.GetVertexID(0));
			listTriangle.Add(tm.GetVertexID(2));
		}

		Mesh mesh = new()
		{
			vertices = listVert.ToArray(),
			triangles = listTriangle.ToArray()
		};

		mesh.RecalculateNormals();

		MeshFilter filter = GetComponent<MeshFilter>();
		if (!filter) filter = gameObject.AddComponent<MeshFilter>();
		filter.sharedMesh = mesh;
		MeshRenderer meshRenderer = GetComponent<MeshRenderer>();
		if(!meshRenderer)meshRenderer = gameObject.AddComponent<MeshRenderer>();
		meshRenderer.material = material;
	}
}

如果不想中间挖洞，使用下面的代码即可：

​
using System.Collections.Generic;
using UnityEngine;
using TriangleNet.Geometry;
using static UnityEditor.Progress;

public class TestTriangleNet : MonoBehaviour
{
	[SerializeField]
	Material material;
	void Start()
	{
		Vector3[] vs = new Vector3[625];
		for (int i = 0; i < vs.Length; i++)
		{
			vs[i] = new Vector3(i % 25, 0, i / 25);
		}

		Polygon poly = new();
		foreach (var v in vs)
		{
			poly.Add(new Vertex(v.x, v.z));
		}

		var triangleMesh = poly.Triangulate();

		List<Vector3> listVert = new();
		foreach (Vertex v in triangleMesh.Vertices)
		{
			listVert.Add(new Vector3(v.X, 0, v.Y));
		}

		List<int> listTriangle = new();
		foreach (var tm in triangleMesh.Triangles)
		{
			listTriangle.Add(tm.GetVertexID(1));
			listTriangle.Add(tm.GetVertexID(0));
			listTriangle.Add(tm.GetVertexID(2));
		}

		Mesh mesh = new()
		{
			vertices = listVert.ToArray(),
			triangles = listTriangle.ToArray()
		};

		mesh.RecalculateNormals();

		MeshFilter filter = GetComponent<MeshFilter>();
		if (!filter) filter = gameObject.AddComponent<MeshFilter>();
		filter.sharedMesh = mesh;
		MeshRenderer meshRenderer = GetComponent<MeshRenderer>();
		if(!meshRenderer)meshRenderer = gameObject.AddComponent<MeshRenderer>();
		meshRenderer.material = material;
	}
}