FarseerPhysics.Common.Decomposition.EarclipDecomposer.TriangulatePolygon C# (CSharp) Method

        private static List<Vertices> TriangulatePolygon(Vertices vertices, float tolerance)
        {
            //FPE note: Check is needed as invalid triangles can be returned in recursive calls.
            if (vertices.Count < 3)
                return new List<Vertices>();

            List<Vertices> results = new List<Vertices>();

            //Recurse and split on pinch points
            Vertices pA, pB;
            Vertices pin = new Vertices(vertices);
            if (ResolvePinchPoint(pin, out pA, out pB, tolerance))
            {
                List<Vertices> mergeA = TriangulatePolygon(pA, tolerance);
                List<Vertices> mergeB = TriangulatePolygon(pB, tolerance);

                if (mergeA.Count == -1 || mergeB.Count == -1)
                    throw new Exception("Can't triangulate your polygon.");

                for (int i = 0; i < mergeA.Count; ++i)
                {
                    results.Add(new Vertices(mergeA[i]));
                }
                for (int i = 0; i < mergeB.Count; ++i)
                {
                    results.Add(new Vertices(mergeB[i]));
                }

                return results;
            }

            Vertices[] buffer = new Vertices[vertices.Count - 2];
            int bufferSize = 0;
            float[] xrem = new float[vertices.Count];
            float[] yrem = new float[vertices.Count];
            for (int i = 0; i < vertices.Count; ++i)
            {
                xrem[i] = vertices[i].X;
                yrem[i] = vertices[i].Y;
            }

            int vNum = vertices.Count;

            while (vNum > 3)
            {
                // Find an ear
                int earIndex = -1;
                float earMaxMinCross = -10.0f;
                for (int i = 0; i < vNum; ++i)
                {
                    if (IsEar(i, xrem, yrem, vNum))
                    {
                        int lower = Remainder(i - 1, vNum);
                        int upper = Remainder(i + 1, vNum);
                        Vector2 d1 = new Vector2(xrem[upper] - xrem[i], yrem[upper] - yrem[i]);
                        Vector2 d2 = new Vector2(xrem[i] - xrem[lower], yrem[i] - yrem[lower]);
                        Vector2 d3 = new Vector2(xrem[lower] - xrem[upper], yrem[lower] - yrem[upper]);

                        d1.Normalize();
                        d2.Normalize();
                        d3.Normalize();
                        float cross12;
                        MathUtils.cross(ref d1, ref d2, out cross12);
                        cross12 = Math.Abs(cross12);

                        float cross23;
                        MathUtils.cross(ref d2, ref d3, out cross23);
                        cross23 = Math.Abs(cross23);

                        float cross31;
                        MathUtils.cross(ref d3, ref d1, out cross31);
                        cross31 = Math.Abs(cross31);

                        //Find the maximum minimum angle
                        float minCross = Math.Min(cross12, Math.Min(cross23, cross31));
                        if (minCross > earMaxMinCross)
                        {
                            earIndex = i;
                            earMaxMinCross = minCross;
                        }
                    }
                }

                // If we still haven't found an ear, we're screwed.
                // Note: sometimes this is happening because the
                // remaining points are collinear.  Really these
                // should just be thrown out without halting triangulation.
                if (earIndex == -1)
                {
                    for (int i = 0; i < bufferSize; i++)
                    {
                        results.Add(buffer[i]);
                    }

                    return results;
                }

                // Clip off the ear:
                // - remove the ear tip from the list

                --vNum;
                float[] newx = new float[vNum];
                float[] newy = new float[vNum];
                int currDest = 0;
                for (int i = 0; i < vNum; ++i)
                {
                    if (currDest == earIndex) ++currDest;
                    newx[i] = xrem[currDest];
                    newy[i] = yrem[currDest];
                    ++currDest;
                }

                // - add the clipped triangle to the triangle list
                int under = (earIndex == 0) ? (vNum) : (earIndex - 1);
                int over = (earIndex == vNum) ? 0 : (earIndex + 1);
                Triangle toAdd = new Triangle(xrem[earIndex], yrem[earIndex], xrem[over], yrem[over], xrem[under],
                                              yrem[under]);
                buffer[bufferSize] = toAdd;
                ++bufferSize;

                // - replace the old list with the new one
                xrem = newx;
                yrem = newy;
            }

            Triangle tooAdd = new Triangle(xrem[1], yrem[1], xrem[2], yrem[2], xrem[0], yrem[0]);
            buffer[bufferSize] = tooAdd;
            ++bufferSize;

            for (int i = 0; i < bufferSize; i++)
            {
                results.Add(new Vertices(buffer[i]));
            }

            return results;
        }