private void OnButtonPressed(int iIndex)
        {
            Graphics3D.Reset();
            switch (iIndex)
            {
            case 0: AngleHoriz = 0.0; AngleVert = 0.0; break;

            case 1: AngleHoriz = 90.0; AngleVert = 0.0; break;

            case 2: AngleHoriz = 180.0; AngleVert = 0.0; break;

            case 3: AngleHoriz = 270.0; AngleVert = 0.0; break;

            case 4: AngleHoriz = 0.0; AngleVert = 90.0; break;

            case 5: AngleHoriz = 45.0 + 0.0; AngleVert = 45.0; break;

            case 6: AngleHoriz = 45.0 + 90.0; AngleVert = 45.0; break;

            case 7: AngleHoriz = 45.0 + 180.0; AngleVert = 45.0; break;

            case 8: AngleHoriz = 45.0 + 270.0; AngleVert = 45.0; break;

            case 9: ShowDimensions = !ShowDimensions; break;

            default: break;
            }
            Invalidate();
        }