Fix of caching of the SlicingParamerters at PrintObject

src/libslic3r/Print.cpp

@@ -523,6 +523,9 @@ exit_for_rearrange_regions:
         invalidated = true;
     }
 
+    for (PrintObject *object : m_objects)
+        object->update_slicing_parameters();
+
     return invalidated;
 }
 
@@ -1098,6 +1101,12 @@ Print::ApplyStatus Print::apply(const Model &model, const DynamicPrintConfig &co
         }
     }
 
+    // Update SlicingParameters for each object where the SlicingParameters is not valid.
+    // If it is not valid, then it is ensured that PrintObject.m_slicing_params is not in use
+    // (posSlicing and posSupportMaterial was invalidated).
+    for (PrintObject *object : m_objects)
+        object->update_slicing_parameters();
+
 #ifdef _DEBUG
     check_model_ids_equal(m_model, model);
 #endif /* _DEBUG */
@@ -1202,13 +1211,13 @@ std::string Print::validate() const
                     break;
                 }
             }
-            SlicingParameters slicing_params0    = m_objects.front()->slicing_parameters();
+            const SlicingParameters &slicing_params0 = m_objects.front()->slicing_parameters();
             size_t            tallest_object_idx = 0;
             if (has_custom_layering)
                 PrintObject::update_layer_height_profile(*m_objects.front()->model_object(), slicing_params0, layer_height_profiles.front());
             for (size_t i = 1; i < m_objects.size(); ++ i) {
                 const PrintObject       *object         = m_objects[i];
-                const SlicingParameters slicing_params = object->slicing_parameters();
+                const SlicingParameters &slicing_params = object->slicing_parameters();
                 if (std::abs(slicing_params.first_print_layer_height - slicing_params0.first_print_layer_height) > EPSILON ||
                     std::abs(slicing_params.layer_height             - slicing_params0.layer_height            ) > EPSILON)
                     return L("The Wipe Tower is only supported for multiple objects if they have equal layer heigths");

src/libslic3r/Print.hpp

@@ -131,7 +131,7 @@ public:
     // by the interactive layer height editor and by the printing process itself.
     // The slicing parameters are dependent on various configuration values
     // (layer height, first layer height, raft settings, print nozzle diameter etc).
-    SlicingParameters           slicing_parameters() const;
+    const SlicingParameters&    slicing_parameters() const { return m_slicing_params; }
     static SlicingParameters    slicing_parameters(const DynamicPrintConfig &full_config, const ModelObject &model_object);
 
     // returns 0-based indices of extruders used to print the object (without brim, support and other helper extrusions)
@@ -161,7 +161,8 @@ protected:
     bool                    invalidate_all_steps();
     // Invalidate steps based on a set of parameters changed.
     bool                    invalidate_state_by_config_options(const std::vector<t_config_option_key> &opt_keys);
-    SlicingParameters       slicing_parameters_internal() const;
+    // If ! m_slicing_params.valid, recalculate.
+    void                    update_slicing_parameters();
 
     static PrintObjectConfig object_config_from_model_object(const PrintObjectConfig &default_object_config, const ModelObject &object, size_t num_extruders);
     static PrintRegionConfig region_config_from_model_volume(const PrintRegionConfig &default_region_config, const ModelVolume &volume, size_t num_extruders);

src/libslic3r/PrintObject.cpp

@@ -104,7 +104,6 @@ void PrintObject::slice()
         return;
     m_print->set_status(10, "Processing triangulated mesh");
     std::vector<coordf_t> layer_height_profile;
-    m_slicing_params = this->slicing_parameters_internal();
     this->update_layer_height_profile(*this->model_object(), m_slicing_params, layer_height_profile);
     m_print->throw_if_canceled();
     this->_slice(layer_height_profile);
@@ -569,8 +568,11 @@ bool PrintObject::invalidate_step(PrintObjectStep step)
     } else if (step == posSlice) {
 		invalidated |= this->invalidate_steps({ posPerimeters, posPrepareInfill, posInfill, posSupportMaterial });
 		invalidated |= m_print->invalidate_steps({ psSkirt, psBrim });
-    } else if (step == posSupportMaterial)
+        this->m_slicing_params.valid = false;
+    } else if (step == posSupportMaterial) {
         invalidated |= m_print->invalidate_steps({ psSkirt, psBrim });
+        this->m_slicing_params.valid = false;
+    }
 
     // Wipe tower depends on the ordering of extruders, which in turn depends on everything.
     // It also decides about what the wipe_into_infill / wipe_into_object features will do,
@@ -1361,16 +1363,11 @@ PrintRegionConfig PrintObject::region_config_from_model_volume(const PrintRegion
     return config;
 }
 
-SlicingParameters PrintObject::slicing_parameters_internal() const
+void PrintObject::update_slicing_parameters()
 {
-    return SlicingParameters::create_from_config(
-        this->print()->config(), m_config, 
-        unscale<double>(this->size(2)), this->object_extruders());
-}
-
-SlicingParameters PrintObject::slicing_parameters() const
-{
-    return this->is_step_done(posSlice) ? m_slicing_params : this->slicing_parameters_internal();
+    if (! m_slicing_params.valid)
+        m_slicing_params = SlicingParameters::create_from_config(
+            this->print()->config(), m_config, unscale<double>(this->size(2)), this->object_extruders());
 }
 
 SlicingParameters PrintObject::slicing_parameters(const DynamicPrintConfig &full_config, const ModelObject &model_object)

src/libslic3r/Slicing.cpp

@@ -149,6 +149,7 @@ SlicingParameters SlicingParameters::create_from_config(
         params.object_print_z_max += print_z;
     }
 
+    params.valid = true;
     return params;
 }
 

src/libslic3r/Slicing.hpp

@@ -42,6 +42,8 @@ struct SlicingParameters
     // Height of the object to be printed. This value does not contain the raft height.
     coordf_t    object_print_z_height() const { return object_print_z_max - object_print_z_min; }
 
+    bool        valid;
+
     // Number of raft layers.
     size_t      base_raft_layers;
     // Number of interface layers including the contact layer.
@@ -100,6 +102,8 @@ static_assert(IsTriviallyCopyable<SlicingParameters>::value, "SlicingParameters
 // The two slicing parameters lead to the same layering as long as the variable layer thickness is not in action.
 inline bool equal_layering(const SlicingParameters &sp1, const SlicingParameters &sp2)
 {
+    assert(sp1.valid);
+    assert(sp2.valid);
     return  sp1.base_raft_layers                    == sp2.base_raft_layers                     &&
             sp1.interface_raft_layers               == sp2.interface_raft_layers                &&
             sp1.base_raft_layer_height              == sp2.base_raft_layer_height               &&