private static void EnsureClockwiseWinding(List <int> indices, List <Vector3> vertices) { if (indices == null || indices.Count < 3) { return; } if (vertices == null || vertices.Count < 1) { return; } for (var i = 0; i < indices.Count; i += 3) { var vert0 = vertices[indices[i + 0]]; var vert1 = vertices[indices[i + 1]]; var vert2 = vertices[indices[i + 2]]; if (!GeometryHelpers.IsCounterClockwiseXY(vert0, vert1, vert2)) { continue; } var temp = indices[i + 1]; indices[i + 1] = indices[i + 2]; indices[i + 2] = temp; } }