介绍

使用开源库创建obj三维模型文件。
开源库地址：https://github.com/JeremyAnsel/JeremyAnsel.Media.WavefrontObj

相关API地址：https://jeremyansel.github.io/JeremyAnsel.Media.WavefrontObj/api/JeremyAnsel.Media.WavefrontObj.ObjFile.html

obj格式解读：https://blog.csdn.net/shebao3333/article/details/132094257

示例

效果图（灰色为外，红色为内）：

测试代码：

            //面片1
            var face1Pts = new float[][]
            {
                new float[]{0,0,0},
                new float[]{0,1,0},
                new float[]{1,1,0},
                new float[]{1,0,0},
            };
            //面片2
            var face2Pts = new float[][]
            {
                new float[]{0,0,0},
                new float[]{1,0,0},
                new float[]{1,0,0.5f},
                new float[]{0,0,0.5f},
            };

            //面片3
            var face3Pts = new float[][]
            {
                new float[]{0,1,0},
                new float[]{0,1,0.5f},
                new float[]{1,1,0.5f},
                new float[]{1,1,0},
            };

            var obj = new ObjFile();

            //用组表示对象
            //第一个组有两个面
            var group1 = new ObjGroup("group1");
            obj.Groups.Add(group1);
            //添加点
            foreach (var pt in face1Pts)
            {
                obj.Vertices.Add(new ObjVertex(pt[0], pt[1], pt[2]));
            }
            //添加面
            var face = new ObjFace();//根据右手定则确定面片的正面（外面）
            face.Vertices.Add(new ObjTriplet(1, 0, 0));
            face.Vertices.Add(new ObjTriplet(2, 0, 0));
            face.Vertices.Add(new ObjTriplet(3, 0, 0));
            face.Vertices.Add(new ObjTriplet(4, 0, 0));
            face.ObjectName = "group1-face1";
            face.MapName = "group1-face1";
            face.MaterialName = "Wall";
            //面片添加到组里，也需要添加到obj的Faces集合中
            group1.Faces.Add(face);
            obj.Faces.Add(face);

            //第一个组的第二个面
            foreach (var pt in face2Pts)
            {
                obj.Vertices.Add(new ObjVertex(pt[0], pt[1], pt[2]));
            }
            var face2 = new ObjFace();
            face2.Vertices.Add(new ObjTriplet(5, 0, 0));
            face2.Vertices.Add(new ObjTriplet(6, 0, 0));
            face2.Vertices.Add(new ObjTriplet(7, 0, 0));
            face2.Vertices.Add(new ObjTriplet(8, 0, 0));
            face2.ObjectName = "group1-face2";
            face2.MapName = "group1-face2";
            face2.MaterialName = "Column";
            group1.Faces.Add(face2);
            obj.Faces.Add(face2);


            //创建第二个对象，第二个对象有一个面
            var group2 = new ObjGroup("group2");
            obj.Groups.Add(group2);
            foreach (var pt in face3Pts)
            {
                obj.Vertices.Add(new ObjVertex(pt[0], pt[1], pt[2]));
            }
            var face3 = new ObjFace();
            face3.Vertices.Add(new ObjTriplet(9, 0, 0));
            face3.Vertices.Add(new ObjTriplet(10, 0, 0));
            face3.Vertices.Add(new ObjTriplet(11, 0, 0));
            face3.Vertices.Add(new ObjTriplet(12, 0, 0));
            face3.ObjectName = "group2-face1";
            face3.MapName = "group2-face1";
            face3.MaterialName = "Window";
            group2.Faces.Add(face3);
            obj.Faces.Add(face3);
           
			//其他参数
            //face.LevelOfDetail = 2;
            //face.MapName = "c";
            //face.MaterialName = "d";
            //face.SmoothingGroupNumber = 10;
            //face.IsBevelInterpolationEnabled = true;
            //face.IsColorInterpolationEnabled = true;
            //face.IsDissolveInterpolationEnabled = true;
            obj.WriteTo("./Tmp.obj");

生成的obj文件内容：

v 0.000000 0.000000 0.000000
v 0.000000 1.000000 0.000000
v 1.000000 1.000000 0.000000
v 1.000000 0.000000 0.000000
v 0.000000 0.000000 0.000000
v 1.000000 0.000000 0.000000
v 1.000000 0.000000 0.500000
v 0.000000 0.000000 0.500000
v 0.000000 1.000000 0.000000
v 0.000000 1.000000 0.500000
v 1.000000 1.000000 0.500000
v 1.000000 1.000000 0.000000
g group1
o group1-face1
usemap group1-face1
usemtl Wall
f 1 2 3 4
o group1-face2
usemap group1-face2
usemtl Column
f 5 6 7 8
g group2
o group2-face1
usemap group2-face1
usemtl Window
f 9 10 11 12

补充：

• 根据右手定则确定面片的正面（外面）
• ObjectName、MapName、MaterialName的赋值可以注释跳过。