XL specific temporary:

- only enable the temp backtracking for XL
- hardcode toolchange time to 4.5s

src/libslic3r/GCode.cpp

@@ -120,13 +120,13 @@ namespace Slic3r {
                 gcode += gcodegen.writer().set_temperature
                 (this->_get_temp(gcodegen) + gcodegen.config().standby_temperature_delta.value, false, extruder_id);
                 gcode.pop_back();
-                gcode += " ;cooldown\n";
+                gcode += " ;cooldown\n"; // this is a marker for GCodeProcessor, so it can supress the commands when needed
             }
         } else {
             // Use the value from filament settings. That one is absolute, not delta.
             gcode += gcodegen.writer().set_temperature(filament_idle_temp.get_at(extruder_id), false, extruder_id);
             gcode.pop_back();
-            gcode += " ;cooldown\n";
+            gcode += " ;cooldown\n"; // this is a marker for GCodeProcessor, so it can supress the commands when needed
         }
 
         return gcode;

src/libslic3r/GCode/GCodeProcessor.cpp

@@ -558,8 +558,7 @@ void GCodeProcessor::apply_config(const PrintConfig& config)
     m_flavor = config.gcode_flavor;
 
 #if ENABLE_GCODE_POSTPROCESS_BACKTRACE
-    m_result.backtrace_enabled = true; /*config.printer_model.value == "MK3MMU2" || config.printer_model.value == "MK3SMMU2S" ||
+    m_result.backtrace_enabled = is_XL_printer(config);
-        config.printer_model.value == "MK2.5MMU2" || config.printer_model.value == "MK2.5SMMU2S" || config.printer_model.value == "MK2SMM";*/
 #endif // ENABLE_GCODE_POSTPROCESS_BACKTRACE
 
     size_t extruders_count = config.nozzle_diameter.values.size();
@@ -572,11 +571,14 @@ void GCodeProcessor::apply_config(const PrintConfig& config)
     m_result.filament_cost.resize(extruders_count);
     m_extruder_temps.resize(extruders_count);
     m_extruder_temps_config.resize(extruders_count);
+    m_extruder_temps_first_layer_config.resize(extruders_count);
+    m_is_XL_printer = is_XL_printer(config);
 
     for (size_t i = 0; i < extruders_count; ++ i) {
         m_extruder_offsets[i]           = to_3d(config.extruder_offset.get_at(i).cast<float>().eval(), 0.f);
         m_extruder_colors[i]            = static_cast<unsigned char>(i);
         m_extruder_temps_config[i]      = static_cast<int>(config.temperature.get_at(i));
+        m_extruder_temps_first_layer_config[i] = static_cast<int>(config.first_layer_temperature.get_at(i));
         m_result.filament_diameters[i]  = static_cast<float>(config.filament_diameter.get_at(i));
         m_result.filament_densities[i]  = static_cast<float>(config.filament_density.get_at(i));
         m_result.filament_cost[i]       = static_cast<float>(config.filament_cost.get_at(i));
@@ -3992,19 +3994,19 @@ void GCodeProcessor::post_process()
                 export_lines.insert_lines(backtrace, cmd,
                     // line inserter
                     [tool_number, this](unsigned int id, float time, float time_diff) {
-                        //const std::string out = "XYYY ; id:" + std::to_string(id) + " time:" + std::to_string(time) + " time diff:" + std::to_string(time_diff) + "\n";
+                        int temperature = int( m_layer_id != 1 ? m_extruder_temps_config[tool_number] : m_extruder_temps_first_layer_config[tool_number]);
-                        const std::string out = "M104 T" + std::to_string(tool_number) + " P" + std::to_string(int(std::round(time_diff))) + " S" + std::to_string(int(m_extruder_temps_config[tool_number])) + "\n";
+                        const std::string out = "M104 T" + std::to_string(tool_number) + " P" + std::to_string(int(std::round(time_diff))) + " S" + std::to_string(temperature) + "\n";
                         return out;
                     },
                     // line replacer
-                    [tool_number](const std::string& line) {
+                    [this, tool_number](const std::string& line) {
                         if (GCodeReader::GCodeLine::cmd_is(line, "M104")) {
                             GCodeReader::GCodeLine gline;
                             GCodeReader reader;
                             reader.parse_line(line, [&gline](GCodeReader& reader, const GCodeReader::GCodeLine& l) { gline = l; });
 
                             float val;
-                            if (gline.has_value('T', val) && gline.raw().find("cooldown") != std::string::npos) {
+                            if (gline.has_value('T', val) && gline.raw().find("cooldown") != std::string::npos && m_is_XL_printer) {
                                 if (static_cast<int>(val) == tool_number)
                                     return std::string("; removed M104\n");
                             }
@@ -4299,6 +4301,8 @@ void GCodeProcessor::set_travel_acceleration(PrintEstimatedStatistics::ETimeMode
 
 float GCodeProcessor::get_filament_load_time(size_t extruder_id)
 {
+    if (m_is_XL_printer)
+        return 4.5f; // FIXME
     return (m_time_processor.filament_load_times.empty() || m_time_processor.extruder_unloaded) ?
         0.0f :
         ((extruder_id < m_time_processor.filament_load_times.size()) ?
@@ -4307,6 +4311,8 @@ float GCodeProcessor::get_filament_load_time(size_t extruder_id)
 
 float GCodeProcessor::get_filament_unload_time(size_t extruder_id)
 {
+    if (m_is_XL_printer)
+        return 0.f; // FIXME
     return (m_time_processor.filament_unload_times.empty() || m_time_processor.extruder_unloaded) ?
         0.0f :
         ((extruder_id < m_time_processor.filament_unload_times.size()) ?

src/libslic3r/GCode/GCodeProcessor.hpp

@@ -547,6 +547,8 @@ namespace Slic3r {
         ExtruderColors m_extruder_colors;
         ExtruderTemps m_extruder_temps;
         ExtruderTemps m_extruder_temps_config;
+        ExtruderTemps m_extruder_temps_first_layer_config;
+        bool  m_is_XL_printer = false;
         float m_parking_position;
         float m_extra_loading_move;
         float m_extruded_last_z;

src/libslic3r/PrintConfig.cpp

@@ -4935,18 +4935,21 @@ std::string get_sla_suptree_prefix(const DynamicPrintConfig &config)
     return slatree;
 }
 
-bool is_XL_printer(const DynamicPrintConfig &cfg)
+static bool is_XL_printer(const std::string& printer_model)
 {
     static constexpr const char *ALIGN_ONLY_FOR = "XL";
+    return boost::algorithm::contains(printer_model, ALIGN_ONLY_FOR);
+}
 
-    bool ret = false;
+bool is_XL_printer(const DynamicPrintConfig &cfg)
-
+{
     auto *printer_model = cfg.opt<ConfigOptionString>("printer_model");
+    return printer_model && is_XL_printer(printer_model->value);    
+}
 
-    if (printer_model)
+bool is_XL_printer(const PrintConfig &cfg)
-        ret = boost::algorithm::contains(printer_model->value, ALIGN_ONLY_FOR);
+{
-
+    return is_XL_printer(cfg.printer_model.value);
-    return ret;
 }
 
 } // namespace Slic3r

src/libslic3r/PrintConfig.hpp

@@ -1192,6 +1192,7 @@ private:
 };
 
 bool is_XL_printer(const DynamicPrintConfig &cfg);
+bool is_XL_printer(const PrintConfig &cfg);
 
 Points get_bed_shape(const DynamicPrintConfig &cfg);
 Points get_bed_shape(const PrintConfig &cfg);