Change retract_restart_extra_toolchange behavior to trigger at each first tool unretraction (but the very first)

supermerill/SuperSlicer#1052

resources/ui_layout/extruder.ui

@@ -36,7 +36,7 @@ group:Retraction wipe
 	setting:idx:wipe_extra_perimeter
 	setting:idx:seam_gap
 group:Retraction when tool is disabled (advanced settings for multi-extruder setups)
-	setting:idx:retract_length_toolchange
-	setting:idx:retract_restart_extra_toolchange
+	setting:label$Minimum retraction:idx:retract_length_toolchange
+	setting:label$Extra unretraction:idx:retract_restart_extra_toolchange
 group:Preview
 	reset_to_filament_color

src/libslic3r/Extruder.cpp

@@ -13,6 +13,8 @@ Tool::Tool(uint16_t id, GCodeConfig* config) :
 Extruder::Extruder(uint16_t id, GCodeConfig* config) :
     Tool(id, config)
 {
+    // set extra_toolchange to be init for when it will be new current extruder
+    m_restart_extra_toolchange = retract_restart_extra_toolchange();
 
     // cache values that are going to be called often
     m_e_per_mm3 = this->extrusion_multiplier();
@@ -46,7 +48,7 @@ double Tool::extrude(double dE)
    The restart_extra argument sets the extra length to be used for
    unretraction. If we're actually performing a retraction, any restart_extra
    value supplied will overwrite the previous one if any. */
-double Tool::retract(double length, double restart_extra)
+double Tool::retract(double length, double restart_extra, double restart_extra_toolchange)
 {
     // in case of relative E distances we always reset to 0 before any output
     if (m_config->use_relative_e_distances)
@@ -56,17 +58,22 @@ double Tool::retract(double length, double restart_extra)
         m_E             -= to_retract;
         m_absolute_E    -= to_retract;
         m_retracted     += to_retract;
-        m_restart_extra = restart_extra;
+        if(!std::isnan(restart_extra))
+            m_restart_extra = restart_extra;
     }
+    if (!std::isnan(restart_extra_toolchange))
+        m_restart_extra_toolchange = restart_extra_toolchange;
     return to_retract;
 }
 
 double Tool::unretract()
 {
-    double dE = m_retracted + m_restart_extra;
+    double dE = m_retracted + m_restart_extra + m_restart_extra_toolchange;
     this->extrude(dE);
     m_retracted     = 0.;
     m_restart_extra = 0.;
+    if(m_restart_extra_toolchange != 0)
+        m_restart_extra_toolchange = 0.;
     return dE;
 }
 

src/libslic3r/Extruder.hpp

@@ -19,12 +19,13 @@ public:
         m_absolute_E    = 0;
         m_retracted     = 0;
         m_restart_extra = 0;
+        m_restart_extra_toolchange = 0; // note: can't call  retract_restart_extra_toolchange(); because virtual inheritance doesn't work when only the tool is build (constructor)
     }
 
     uint16_t id() const { return m_id; }
 
     virtual double extrude(double dE);
-    virtual double retract(double length, double restart_extra);
+    virtual double retract(double length, double restart_extra, double restart_extra_from_toolchange);
     virtual double unretract();
     double E() const { return m_E; }
     void   reset_E() { m_E = 0.; }
@@ -67,6 +68,7 @@ protected:
     double       m_retracted;
     // When retracted, this value stores the extra amount of priming on deretraction.
     double       m_restart_extra;
+    double       m_restart_extra_toolchange;
     double       m_e_per_mm3;
 };
 

src/libslic3r/GCode.cpp

@@ -1469,6 +1469,9 @@ void GCode::_do_export(Print& print, FILE* file, ThumbnailsGeneratorCallback thu
         m_writer.toolchange(initial_extruder_id);
     }
 
+    // ensure the first tool doesn't "extra_retract"
+    m_writer.unretract();
+
     //write temps after custom gcodes to ensure the temperature are good. (after tool selection)
     if ((initial_extruder_id != (uint16_t)-1) && !this->config().start_gcode_manual && print.config().first_layer_temperature.get_at(initial_extruder_id) != 0)
         this->_print_first_layer_extruder_temperatures(file, print, start_gcode, initial_extruder_id, true);

src/libslic3r/GCodeWriter.cpp

@@ -601,12 +601,14 @@ std::string GCodeWriter::retract(bool before_wipe)
         return this->_retract(
             factor * config_region->print_retract_length,
             factor * m_tool->retract_restart_extra(),
+            NAN,
             "retract"
         );
     }
     return this->_retract(
         factor * m_tool->retract_length(),
         factor * m_tool->retract_restart_extra(),
+        NAN,
         "retract"
     );
 }
@@ -617,12 +619,13 @@ std::string GCodeWriter::retract_for_toolchange(bool before_wipe)
     assert(factor >= 0. && factor <= 1. + EPSILON);
     return this->_retract(
         factor * m_tool->retract_length_toolchange(),
+        NAN,
         factor * m_tool->retract_restart_extra_toolchange(),
         "retract for toolchange"
     );
 }
 
-std::string GCodeWriter::_retract(double length, double restart_extra, const std::string &comment)
+std::string GCodeWriter::_retract(double length, double restart_extra, double restart_extra_toolchange, const std::string &comment)
 {
     std::ostringstream gcode;
     
@@ -637,9 +640,10 @@ std::string GCodeWriter::_retract(double length, double restart_extra, const std
         double area = d * d * PI/4;
         length = length * area;
         restart_extra = restart_extra * area;
+        restart_extra_toolchange = restart_extra_toolchange * area;
     }
     
-    double dE = m_tool->retract(length, restart_extra);
+    double dE = m_tool->retract(length, restart_extra, restart_extra_toolchange);
     assert(dE >= 0);
     assert(dE < 10000000);
     if (dE != 0) {

src/libslic3r/GCodeWriter.hpp

@@ -100,7 +100,7 @@ private:
     Vec3d           m_pos = Vec3d::Zero();
 
     std::string _travel_to_z(double z, const std::string &comment);
-    std::string _retract(double length, double restart_extra, const std::string &comment);
+    std::string _retract(double length, double restart_extra, double restart_extra_toolchange, const std::string &comment);
 
     // if positive, it's set, and the next lift wil have this extra lift
     double extra_lift = 0;

src/libslic3r/PrintConfig.cpp

@@ -3281,7 +3281,8 @@ void PrintConfigDef::init_fff_params()
     def->full_label = L("Retraction Length (Toolchange)");
     def->tooltip = L("When retraction is triggered before changing tool, filament is pulled back "
                    "by the specified amount (the length is measured on raw filament, before it enters "
-                   "the extruder).");
+                   "the extruder)."
+                    "\nNote: This value will be unretracted when this extruder will load the next time.");
     def->sidetext = L("mm (zero to disable)");
     def->mode = comExpert;
     def->min = 0;
@@ -3361,7 +3362,8 @@ void PrintConfigDef::init_fff_params()
     def->label = L("Extra length on restart");
     def->full_label = L("Extrat length on toolchange restart");
     def->tooltip = L("When the retraction is compensated after changing tool, the extruder will push "
-                   "this additional amount of filament.");
+                    "this additional amount of filament"
+                    " (but not on the first extruder after start, as it should already be loaded).");
     def->sidetext = L("mm");
     def->mode = comExpert;
     def->is_vector_extruder = true;