AutoStereogramDemo.AutoStereogramBuilder.IsDivisionRequired C# (CSharp) Method

        private bool IsDivisionRequired(SurfaceRenderStackFrame stackFrame, SurfaceFunc func)
        {
            // if some points are out of func domain (when grid cell located on domain edge), then use interpolated values

            List<double> zValues = new List<double>(3);

            for (int x1 = 0; x1 <= 2; x1 += 2)
                for (int y1 = 0; y1 <= 2; y1 += 2)
                {
                    if (stackFrame.Points[x1, y1].Z != null)
                        continue;

                    zValues.Clear();

                    for (int x2 = 0; x2 <= 2; x2 += 2)
                        for (int y2 = 0; y2 <= 2; y2 += 2)
                        {
                            if (stackFrame.Points[x2, y2].Z == null)
                                continue;

                            double? z = func(stackFrame.Points[x2, y2].X + (stackFrame.Points[x2, y2].X - stackFrame.Points[x1, y1].X) / 100,
                             stackFrame.Points[x2, y2].Y + (stackFrame.Points[x2, y2].Y - stackFrame.Points[x1, y1].Y) / 100);

                            if (z != null)
                                zValues.Add(stackFrame.Points[x2, y2].Z.Value + (stackFrame.Points[x2, y2].Z.Value - z.Value) * 100);
                        }

                    if (zValues.Count == 0)
                        return false;

                    double zAvg = zValues.Average();

                    stackFrame.Points[x1, y1].XLeftProj = GetXProj(stackFrame.Points[x1, y1].X, zAvg, true);
                    stackFrame.Points[x1, y1].XRightProj = GetXProj(stackFrame.Points[x1, y1].X, zAvg, false);
                    stackFrame.Points[x1, y1].YProj = GetYProj(stackFrame.Points[x1, y1].Y, zAvg);
                }

            // if adjacent points of grid with same x or y coordinate are projected to non-adjacent points on the screen, then divide grid cell on subcells

            return IsDivisionRequired(stackFrame.Points[0, 0].XLeftProj, stackFrame.Points[0, 0].YProj, stackFrame.Points[2, 0].XLeftProj, stackFrame.Points[2, 0].YProj,
             stackFrame.Points[2, 2].XLeftProj, stackFrame.Points[2, 2].YProj, stackFrame.Points[0, 2].XLeftProj, stackFrame.Points[0, 2].YProj) ||
             IsDivisionRequired(stackFrame.Points[0, 0].XRightProj, stackFrame.Points[0, 0].YProj, stackFrame.Points[2, 0].XRightProj, stackFrame.Points[2, 0].YProj,
             stackFrame.Points[2, 2].XRightProj, stackFrame.Points[2, 2].YProj, stackFrame.Points[0, 2].XRightProj, stackFrame.Points[0, 2].YProj);
        }