Unity-Sprite mesh outline caculation

SpriteOutline.cs

public struct LineP
        {
            public uint v1;
            public uint v2;

            public LineP(uint v1,uint v2)
            {
                this.v1 = v1;
                this.v2 = v2;
            }

            public override bool Equals(object obj)
            {
                if (!(obj is LineP)) return false;

                LineP o = (LineP)obj;
                return (o.v1 == v1 && o.v2 == v2)||(o.v1 == v2 && o.v2 == v1);
            }

            public override string ToString()
            {
                return v1 + " " + v2;
            }
        }

public static List<Vector3> ProcessSpr(Sprite spr,out Polygon2D polygon)
        {
            List<LineP> line = new List<LineP>();
            for(int i = 0; i < spr.triangles.Length / 3; i++)
            {
                var v1 = spr.triangles[i * 3];
                var v2 = spr.triangles[i * 3 + 1];
                var v3 = spr.triangles[i * 3 + 2];

                var p1 = new LineP(v1, v2);
                var p2 = new LineP(v2, v3);
                var p3 = new LineP(v3, v1);

                if (line.Contains(p1))
                {
                    line.Remove(p1);
                }
                else
                {
                    line.Add(p1);
                }

                if (line.Contains(p2))
                {
                    line.Remove(p2);
                }
                else
                {
                    line.Add(p2);
                }

                if (line.Contains(p3))
                {
                    line.Remove(p3);
                }
                else
                {
                    line.Add(p3);
                }
            }

            uint n = 0;
            List<uint> linstr = new List<uint>();
            linstr.Add(n);
            while (true)
            {
                var la = line.Find((l) => l.v1 == n);
                if (la.v2 == 0) break;
                linstr.Add(la.v2);
                n = la.v2;
            }

            List<Vector3> vert = new List<Vector3>();

            List<Vector2> counter = new List<Vector2>();

            for (int i = 0; i < linstr.Count; i++)
            {
                Vector2 v2 = spr.vertices[linstr[i]];
                vert.Add(new Vector3(v2.x, 0, v2.y));
                counter.Add(spr.vertices[linstr[i]]);
            }

            polygon = new Polygon2D(counter.ToArray());
            return vert;
        }