C#合并OBJ模型并处理顶点、法线、 纹理坐标信息

要合并多个OBJ模型，可以先将它们读入内存中并解析出顶点、法线和纹理坐标等信息，然后将它们合并成一个大的模型，最后再将合并后的模型保存下来。

以下是一个示例代码，可以将多个OBJ文件合并成一个新的OBJ文件，并处理顶点、法线和纹理坐标信息：

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;

namespace MergeObj
{
    class Program
    {
        static void Main(string[] args)
        {
            // 读取多个OBJ文件
            var models = new List<Model>();
            foreach (var file in Directory.GetFiles("models", "*.obj"))
            {
                var model = new Model(file);
                models.Add(model);
            }

            // 合并顶点、法线和纹理坐标
            var vertices = new List<Vector3>();
            var normals = new List<Vector3>();
            var texCoords = new List<Vector2>();
            var faces = new List<Face>();
            int vertexOffset = 0;
            int normalOffset = 0;
            int texCoordOffset = 0;
            foreach (var model in models)
            {
                vertices.AddRange(model.Vertices);
                normals.AddRange(model.Normals);
                texCoords.AddRange(model.TexCoords);
                foreach (var face in model.Faces)
                {
                    faces.Add(new Face(
                        face.Vertices.Select(v => v + vertexOffset),
                        face.Normals.Select(n => n + normalOffset),
                        face.TexCoords.Select(t => t + texCoordOffset)));
                }
                vertexOffset += model.Vertices.Count;
                normalOffset += model.Normals.Count;
                texCoordOffset += model.TexCoords.Count;
            }

            // 保存合并后的OBJ文件
            using (var writer = new StreamWriter("merged.obj"))
            {
                foreach (var vertex in vertices)
                {
                    writer.WriteLine($"v {vertex.X} {vertex.Y} {vertex.Z}");
                }
                foreach (var normal in normals)
                {
                    writer.WriteLine($"vn {normal.X} {normal.Y} {normal.Z}");
                }
                foreach (var texCoord in texCoords)
                {
                    writer.WriteLine($"vt {texCoord.X} {texCoord.Y}");
                }
                foreach (var face in faces)
                {
                    writer.Write("f");
                    for (int i = 0; i < face.Vertices.Count; i++)
                    {
                        int v = face.Vertices[i];
                        int n = face.Normals[i];
                        int t = face.TexCoords[i];
                        writer.Write($" {v}/{t}/{n}");
                    }
                    writer.WriteLine();
                }
            }
        }
    }

    class Model
    {
        public List<Vector3> Vertices { get; } = new List<Vector3>();
        public List<Vector3> Normals { get; } = new List<Vector3>();
        public List<Vector2> TexCoords { get; } = new List<Vector2>();
        public List<Face> Faces { get; } = new List<Face>();

        public Model(string filename)
        {
            using (var reader = new StreamReader(filename))
            {
                string line;
                while ((line = reader.ReadLine()) != null)
                {
                    string[] parts = line.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
                    if (parts.Length == 0) continue;

                    switch (parts[0])
                    {
                        case "v":
                            float x = float.Parse(parts[1]);
                            float y = float.Parse(parts[2]);
                            float z = float.Parse(parts[3]);
                            Vertices.Add(new Vector3(x, y, z));
                            break;
                        case "vn":
                            float nx = float.Parse(parts[1]);
                            float ny = float.Parse(parts[2]);
                            float nz = float.Parse(parts[3]);
                            Normals.Add(new Vector3(nx, ny, nz));
                            break;
                        case "vt":
                            float u = float.Parse(parts[1]);
                            float v = float.Parse(parts[2]);
                            TexCoords.Add(new Vector2(u, v));
                            break;
                        case "f":
                            var face = new Face();
                            for (int i = 1; i < parts.Length; i++)
                            {
                                string[] components = parts[i].Split('/');
                                int vIndex = int.Parse(components[0]) - 1;
                                int nIndex = int.Parse(components[2]) - 1;
                                int tIndex = components.Length > 1 ? int.Parse(components[1]) - 1 : 0;
                                face.Vertices.Add(vIndex);
                                face.Normals.Add(nIndex);
                                face.TexCoords.Add(tIndex);
                            }
                            Faces.Add(face);
                            break;
                    }
                }
            }
        }
    }

    class Vector2
    {
        public float X { get; }
        public float Y { get; }

        public Vector2(float x, float y)
        {
            X = x;
            Y = y;
        }
    }

    class Vector3
    {
        public float X { get; }
        public float Y { get; }
        public float Z { get; }

        public Vector3(float x, float y, float z)
        {
            X = x;
            Y = y;
            Z = z;
        }
    }

    class Face
    {
        public List<int> Vertices { get; } = new List<int>();
        public List<int> Normals { get; } = new List<int>();
        public List<int> TexCoords { get; } = new List<int>();

        public Face() { }

        public Face(IEnumerable<int> vertices, IEnumerable<int> normals, IEnumerable<int> texCoords)
        {
            Vertices.AddRange(vertices);
            Normals.AddRange(normals);
            TexCoords.AddRange(texCoords);
        }
    }
}

这个示例代码假设所有的OBJ文件都在“models”文件夹下，输出的合并后的OBJ文件名为“merged.obj”。可以根据实际情况修改相关路径和文件名。