Fix of #3919 (extremely wide wipe tower with 0.35mm FAST profile)

This is an excerpt from ec86d94, which was recently reverted because
the other changes from that commit broke some functionality.

src/libslic3r/GCode/ToolOrdering.cpp

@@ -94,7 +94,7 @@ ToolOrdering::ToolOrdering(const PrintObject &object, unsigned int first_extrude
     // Reorder the extruders to minimize tool switches.
     this->reorder_extruders(first_extruder);
 
-    this->fill_wipe_tower_partitions(object.print()->config(), object.layers().front()->print_z - object.layers().front()->height);
+    this->fill_wipe_tower_partitions(object.print()->config(), object.layers().front()->print_z - object.layers().front()->height, object.config().layer_height);
 
     this->collect_extruder_statistics(prime_multi_material);
 }
@@ -107,6 +107,7 @@ ToolOrdering::ToolOrdering(const Print &print, unsigned int first_extruder, bool
 
     // Initialize the print layers for all objects and all layers.
     coordf_t object_bottom_z = 0.;
+    coordf_t max_layer_height = 0.;
     {
         std::vector<coordf_t> zs;
         for (auto object : print.objects()) {
@@ -122,6 +123,8 @@ ToolOrdering::ToolOrdering(const Print &print, unsigned int first_extruder, bool
                     object_bottom_z = layer->print_z - layer->height;
                     break;
                 }
+
+            max_layer_height = std::max(max_layer_height, object->config().layer_height.value);
         }
         this->initialize_layers(zs);
     }
@@ -144,7 +147,7 @@ ToolOrdering::ToolOrdering(const Print &print, unsigned int first_extruder, bool
     // Reorder the extruders to minimize tool switches.
     this->reorder_extruders(first_extruder);
 
-    this->fill_wipe_tower_partitions(print.config(), object_bottom_z);
+    this->fill_wipe_tower_partitions(print.config(), object_bottom_z, max_layer_height);
 
     this->collect_extruder_statistics(prime_multi_material);
 }
@@ -318,7 +321,7 @@ void ToolOrdering::reorder_extruders(unsigned int last_extruder_id)
         }    
 }
 
-void ToolOrdering::fill_wipe_tower_partitions(const PrintConfig &config, coordf_t object_bottom_z)
+void ToolOrdering::fill_wipe_tower_partitions(const PrintConfig &config, coordf_t object_bottom_z, coordf_t max_object_layer_height)
 {
     if (m_layer_tools.empty())
         return;
@@ -351,6 +354,10 @@ void ToolOrdering::fill_wipe_tower_partitions(const PrintConfig &config, coordf_
             mlh = 0.75 * config.nozzle_diameter.values[i];
         max_layer_height = std::min(max_layer_height, mlh);
     }
+    // The Prusa3D Fast (0.35mm layer height) print profile sets a higher layer height than what is normally allowed
+    // by the nozzle. This is a hack and it works by increasing extrusion width. See GH #3919.
+    max_layer_height = std::max(max_layer_height, max_object_layer_height);
+
     for (size_t i = 0; i + 1 < m_layer_tools.size(); ++ i) {
         const LayerTools &lt      = m_layer_tools[i];
         const LayerTools &lt_next = m_layer_tools[i + 1];
@@ -404,7 +411,7 @@ void ToolOrdering::fill_wipe_tower_partitions(const PrintConfig &config, coordf_
         unsigned int j = i+1;
         double last_wipe_tower_print_z = lt_next.print_z;
         while (++j < m_layer_tools.size()-1 && !m_layer_tools[j].has_wipe_tower)
-            if (m_layer_tools[j+1].print_z - last_wipe_tower_print_z > max_layer_height) {
+            if (m_layer_tools[j+1].print_z - last_wipe_tower_print_z > max_layer_height + EPSILON) {
                 m_layer_tools[j].has_wipe_tower = true;
                 last_wipe_tower_print_z = m_layer_tools[j].print_z;
             }

src/libslic3r/GCode/ToolOrdering.hpp

@@ -168,7 +168,7 @@ private:
     void				initialize_layers(std::vector<coordf_t> &zs);
     void 				collect_extruders(const PrintObject &object, const std::vector<std::pair<double, unsigned int>> &per_layer_extruder_switches);
     void				reorder_extruders(unsigned int last_extruder_id);
-    void 				fill_wipe_tower_partitions(const PrintConfig &config, coordf_t object_bottom_z);
+    void 				fill_wipe_tower_partitions(const PrintConfig &config, coordf_t object_bottom_z, coordf_t max_layer_height);
     void 				collect_extruder_statistics(bool prime_multi_material);
 
     std::vector<LayerTools>    m_layer_tools;

src/slic3r/GUI/GUI_ObjectList.hpp

@@ -13,6 +13,8 @@
 #include "wxExtensions.hpp"
 #include "ObjectDataViewModel.hpp"
 
+#include "libslic3r/PrintConfig.hpp"
+
 class wxBoxSizer;
 class wxBitmapComboBox;
 class wxMenuItem;