You can customize the orientation by specifying a front and an up vector for the model using HPS::Model::SetOrientation. The navigation cube orients along the model orientation.
https://docs.techsoft3d.com/hps/latest/api_ref/cs/class_h_p_s_1_1_model.html#function-HPS.Model.SetOrientation
When just opening the model in sandbox:
When setting the orientation as below:
HPS::Vector up(0, 0, 1);
HPS::Vector front(1, 0, 0);
GetCanvas().GetFrontView().GetAttachedModel().SetOrientation(up, front);
