ENH: move the volumes grouping process to an indivial function

grouping of volumes in the slicing process, which will be used by the brim generation processes,
is moved to an indivial function from the fixed_slicing_errors function.

Change-Id: I241081823a671829d8cc4e923da5f6f22776c410
(cherry picked from commit 18a7b541ee48f3c01319d5835c05610c3d8ca0ae)

src/libslic3r/Layer.hpp

@@ -197,7 +197,7 @@ public:
 protected:
     friend class PrintObject;
     friend std::vector<Layer*> new_layers(PrintObject*, const std::vector<coordf_t>&);
-    friend std::string fix_slicing_errors(PrintObject* object, LayerPtrs&, const std::function<void()>&);
+    friend std::string fix_slicing_errors(PrintObject* object, LayerPtrs&, const std::function<void()>&, int &);
 
     Layer(size_t id, PrintObject *object, coordf_t height, coordf_t print_z, coordf_t slice_z) :
         upper_layer(nullptr), lower_layer(nullptr), slicing_errors(false),

src/libslic3r/PrintObjectSlice.cpp

@@ -608,7 +608,7 @@ void reGroupingLayerPolygons(std::vector<groupedVolumeSlices>& gvss, ExPolygons
     }
 }
 
-std::string fix_slicing_errors(PrintObject* object, LayerPtrs &layers, const std::function<void()> &throw_if_canceled)
+std::string fix_slicing_errors(PrintObject* object, LayerPtrs &layers, const std::function<void()> &throw_if_canceled, int &firstLayerReplacedBy)
 {
     std::string error_msg;//BBS
 
@@ -720,10 +720,14 @@ std::string fix_slicing_errors(PrintObject* object, LayerPtrs &layers, const std
 
     // BBS: first layer slices are sorted by volume group, if the first layer is empty and replaced by the 2nd layer
 // the later will be stored in "object->firstLayerObjGroupsMod()"
-    int firstLayerReplacedBy = 0;
     if (!buggy_layers.empty() && buggy_layers.front() == 0 && layers.size() > 1)
         firstLayerReplacedBy = 1;
 
+    return error_msg;
+}
+
+void groupingVolumesForBrim(PrintObject* object, LayerPtrs& layers, int firstLayerReplacedBy)
+{
     const auto           scaled_resolution = scaled<double>(object->print()->config().resolution.value);
     auto partsObjSliceByVolume = findPartVolumes(object->firstLayerObjSliceMod(), object->model_object()->volumes);
     groupingVolumes(partsObjSliceByVolume, object->firstLayerObjGroupsMod(), scaled_resolution, firstLayerReplacedBy);
@@ -731,8 +735,6 @@ std::string fix_slicing_errors(PrintObject* object, LayerPtrs &layers, const std
 
     // BBS: the actual first layer slices stored in layers are re-sorted by volume group and will be used to generate brim
     reGroupingLayerPolygons(object->firstLayerObjGroupsMod(), layers.front()->lslices);
-
-    return error_msg;
 }
 
 // Called by make_perimeters()
@@ -757,10 +759,12 @@ void PrintObject::slice()
     m_layers = new_layers(this, generate_object_layers(m_slicing_params, layer_height_profile));
     this->slice_volumes();
     m_print->throw_if_canceled();
+    int firstLayerReplacedBy = 0;
+
 #if 1
     // Fix the model.
     //FIXME is this the right place to do? It is done repeateadly at the UI and now here at the backend.
-    std::string warning = fix_slicing_errors(this, m_layers, [this](){ m_print->throw_if_canceled(); });
+    std::string warning = fix_slicing_errors(this, m_layers, [this](){ m_print->throw_if_canceled(); }, firstLayerReplacedBy);
     m_print->throw_if_canceled();
     //BBS: send warning message to slicing callback
     if (!warning.empty()) {
@@ -768,6 +772,10 @@ void PrintObject::slice()
         this->active_step_add_warning(PrintStateBase::WarningLevel::CRITICAL, warning, PrintStateBase::SlicingReplaceInitEmptyLayers);
     }
 #endif
+
+    // BBS: the actual first layer slices stored in layers are re-sorted by volume group and will be used to generate brim
+    groupingVolumesForBrim(this, m_layers, firstLayerReplacedBy);
+
     // Update bounding boxes, back up raw slices of complex models.
     tbb::parallel_for(
         tbb::blocked_range<size_t>(0, m_layers.size()),