private void applyModelView()
{
// Since there is no context.SetCTM, only ConcatCTM
// get the current transform, invert it, and concat this to
// obtain the identity. Then we concatenate the value passed
context.ConcatCTM (context.GetCTM().Invert());
var modelView = CGAffineTransform.Multiply(modelMatrix.transform, viewMatrix.transform);
// Console.WriteLine("------------ apply Model View ------");
// Console.WriteLine("Model: " + modelMatrix.transform);
// Console.WriteLine("View: " + viewMatrix.transform);
// Console.WriteLine("ModelView: " + modelView);
// Console.WriteLine("------------ end apply Model View ------\n\n");
// we apply the Model View matrix passed to the context
context.ConcatCTM (modelView);
}