fix: the 3D scene is drawn in the wrong view for the first half second of startup (#15830)

src/slic3r/GUI/GUI_App.cpp

@@ -865,6 +865,9 @@ void GUI_App::post_init()
         plater_->canvas3D()->enable_render(false);
         mainframe->select_tab(TAB_ID_PREPARE);
         plater_->select_view_3D("3D");
+        // The first render happens before the queued new_project() sets the same view.
+        plater_->get_camera().select_view("topfront");
+        plater_->get_camera().requires_zoom_to_bed = true;
         //BBS init the opengl resource here
         if (!plater_->canvas3D()->get_wxglcanvas()->IsShownOnScreen() ||
             !plater_->canvas3D()->make_current_for_postinit()) {

src/slic3r/GUI/Plater.cpp

@@ -7033,7 +7033,7 @@ struct Plater::priv
     void remove(size_t obj_idx);
     bool delete_object_from_model(size_t obj_idx, bool refresh_immediately = true); //BBS
     void delete_all_objects_from_model();
-    void reset(bool apply_presets_change = false);
+    void reset(bool apply_presets_change = false, bool reload_presets = true);
     void center_selection();
     void drop_selection();
     void mirror(Axis axis);
@@ -7891,7 +7891,8 @@ Plater::priv::priv(Plater *q, MainFrame *main_frame)
             
             if (this->q->get_project_filename().IsEmpty() && this->q->is_empty_project()) {
                 int skip_confirm = e.GetInt();
-                this->q->new_project(skip_confirm, true);
+                // Skips the preset reload; trigger_restore_project()'s callers load the presets first.
+                this->q->new_project(skip_confirm, true, wxString(), false);
             }
         });
         //wxPostEvent(this->q, wxCommandEvent{EVT_RESTORE_PROJECT});
@@ -10356,7 +10357,7 @@ void Plater::priv::delete_all_objects_from_model()
     model.plates_custom_gcodes.clear();
 }
 
-void Plater::priv::reset(bool apply_presets_change)
+void Plater::priv::reset(bool apply_presets_change, bool reload_presets)
 {
     // TakeSnapshot below and load_current_presets() further down each re-evaluate the
     // aggregate dirty flag against a baseline that hasn't been reset yet, so they can toggle
@@ -10431,7 +10432,7 @@ void Plater::priv::reset(bool apply_presets_change)
     wxGetApp().preset_bundle->reset_project_embedded_presets();
     if (apply_presets_change)
         wxGetApp().apply_keeped_preset_modifications();
-    else
+    else if (reload_presets)
         wxGetApp().load_current_presets(false, false);
 
     //BBS
@@ -15351,7 +15352,7 @@ Print&          Plater::fff_print()         { return p->fff_print; }
 const SLAPrint& Plater::sla_print() const   { return p->sla_print; }
 SLAPrint&       Plater::sla_print()         { return p->sla_print; }
 
-int Plater::new_project(bool skip_confirm, bool silent, const wxString& project_name)
+int Plater::new_project(bool skip_confirm, bool silent, const wxString& project_name, bool reload_presets)
 {
     model().calib_pa_pattern.reset(nullptr);
     model().plates_custom_gcodes.clear();
@@ -15399,7 +15400,7 @@ int Plater::new_project(bool skip_confirm, bool silent, const wxString& project_
         // completes, so hold notifications until then to avoid firing on transient flips.
         ProjectDirtyStateManager::NotificationSuppressor dirty_notify_suppressor(p->dirty_state);
 
-        reset(transfer_preset_changes);
+        reset(transfer_preset_changes, reload_presets);
         reset_project_dirty_after_save();
         reset_project_dirty_initial_presets();
         wxGetApp().update_saved_preset_from_current_preset();
@@ -17984,7 +17985,7 @@ void Plater::deselect_all() { p->deselect_all(); }
 void Plater::exit_gizmo() { p->exit_gizmo(); }
 
 void Plater::remove(size_t obj_idx) { p->remove(obj_idx); }
-void Plater::reset(bool apply_presets_change) { p->reset(apply_presets_change); }
+void Plater::reset(bool apply_presets_change, bool reload_presets) { p->reset(apply_presets_change, reload_presets); }
 void Plater::reset_with_confirm()
 {
     if (p->model.objects.empty() || MessageDialog(static_cast<wxWindow *>(this), _L("All objects will be removed, continue?"),

src/slic3r/GUI/Plater.hpp

@@ -339,7 +339,7 @@ public:
     // Helper: returns config indices where filament_is_mixed == false
     std::vector<size_t> physical_filament_config_indices() const;
 
-    int new_project(bool skip_confirm = false, bool silent = false, const wxString& project_name = wxString());
+    int new_project(bool skip_confirm = false, bool silent = false, const wxString& project_name = wxString(), bool reload_presets = true);
     // BBS: save & backup
     void load_project(wxString const & filename = "", wxString const & originfile = "-");
     int save_project(bool saveAs = false);
@@ -499,7 +499,7 @@ public:
     void deselect_all();
     void exit_gizmo();
     void remove(size_t obj_idx);
-    void reset(bool apply_presets_change = false);
+    void reset(bool apply_presets_change = false, bool reload_presets = true);
     void reset_with_confirm();
     //BBS: return int for various result
     int close_with_confirm(std::function<bool(bool yes_or_no)> second_check = nullptr); // BBS close project