Non-linear extrusion

src/libslic3r/GCode.cpp

@@ -3108,6 +3108,24 @@ double cap_speed(
     return speed;
 }
 
+// https://arachnoid.com/polysolve/
+double GCodeGenerator::_regress(double x) {
+  double terms[3];
+
+  int extr_id = this->m_writer.extruder()->id();
+  terms[0] = m_writer.config.extrusion_regression_c.get_at(extr_id);
+  terms[1] = m_writer.config.extrusion_regression_b.get_at(extr_id);
+  terms[2] = m_writer.config.extrusion_regression_a.get_at(extr_id);
+
+  double t = 1;
+  double r = 0;
+  for (double c : terms) {
+    r += c * t;
+    t *= x;
+  }
+  return r;
+}
+
 std::string GCodeGenerator::_extrude(
     const ExtrusionAttributes       &path_attr,
     const Geometry::ArcWelder::Path &path,
@@ -3332,15 +3350,37 @@ std::string GCodeGenerator::_extrude(
             }
             if (radius == 0) {
                 // Extrude line segment.
-                if (const double line_length = (p - prev).norm(); line_length > 0)
-                    gcode += m_writer.extrude_to_xy(p, e_per_mm * line_length, comment);
+                if (const double line_length = (p - prev).norm(); line_length > 0) {
+
+                    double dE = e_per_mm * line_length;
+                    double tm = line_length/speed;
+                    double k = _regress(dE / tm);
+                    std::string ln = m_writer.extrude_to_xy(p, dE * k, comment);
+
+                    if (k > 1) {
+                        std::string ee = (!this->config().extrusion_regression_show ? ";_K_" : ";K:") + std::to_string(std::round(k * 1000000) / 1000000) + "\n";
+                        int i = ln.find("\n");
+                        ln = ln.replace(i, strlen("\n"),ee);
+                    }
+                    gcode += ln;
+				}
             } else {
                 double angle = Geometry::ArcWelder::arc_angle(prev.cast<double>(), p.cast<double>(), double(radius));
                 assert(angle > 0);
                 const double line_length = angle * std::abs(radius);
                 const double dE          = e_per_mm * line_length;
                 assert(dE > 0);
-                gcode += m_writer.extrude_to_xy_G2G3IJ(p, ij, it->ccw(), dE, comment);
+
+                double tm = line_length/speed;
+                double k = _regress(dE / (line_length/speed));
+                std::string ln = m_writer.extrude_to_xy_G2G3IJ(p, ij, it->ccw(), dE * k, comment);
+
+                if (k > 1 && !this->config().extrusion_regression_show) {
+                    std::string ee = (!this->config().extrusion_regression_show ? ";_K_" : ";K:") + std::to_string(std::round(k * 1000000) / 1000000) + "\n";
+                    int i = ln.find("\n");
+                    ln = ln.replace(i, strlen("\n"),ee);
+                }
+                gcode += ln;
             }
             prev = p;
             prev_exact = p_exact;

src/libslic3r/GCode.hpp

@@ -454,6 +454,7 @@ class GCodeGenerator {
     // Back-pointer to Print (const).
     const Print*                        m_print;
 
+    double                              _regress(double x);
     std::string                         _extrude(
         const ExtrusionAttributes &attribs, const Geometry::ArcWelder::Path &path, const std::string_view description, double speed = -1);
     void                                print_machine_envelope(GCodeOutputStream &file, const Print &print);

src/libslic3r/GCode/GCodeProcessor.cpp

@@ -2551,14 +2551,26 @@ void GCodeProcessor::process_G0(const GCodeReader::GCodeLine& line)
 {
     process_G1(line);
 }
-
+#pragma optimize("",off)
 void GCodeProcessor::process_G1(const GCodeReader::GCodeLine& line)
 {
     std::array<std::optional<double>, 4> g1_axes = { std::nullopt, std::nullopt, std::nullopt, std::nullopt };
     if (line.has_x()) g1_axes[X] = (double)line.x();
     if (line.has_y()) g1_axes[Y] = (double)line.y();
     if (line.has_z()) g1_axes[Z] = (double)line.z();
-    if (line.has_e()) g1_axes[E] = (double)line.e();
+    if (line.has_e()){
+
+        std::string_view cmnt = line.comment();
+        g1_axes[E] = (double)line.e();
+        int st = cmnt.find("_K_");
+        if (st >= 0) {
+            st += 3;
+            int eol = cmnt.find("\n");
+            std::string es(cmnt.substr(st, eol));
+            double k = atof(es.c_str());
+            g1_axes[E] = g1_axes[E].value() / k ;
+        }
+    }
     std::optional<double> g1_feedrate = std::nullopt;
     if (line.has_f()) g1_feedrate = (double)line.f();
     process_G1(g1_axes, g1_feedrate);

src/libslic3r/Preset.cpp

@@ -481,6 +481,7 @@ static std::vector<std::string> s_Preset_filament_options {
     "filament_unloading_speed", "filament_unloading_speed_start", "filament_unload_time", "filament_toolchange_delay", "filament_cooling_moves",
     "filament_cooling_initial_speed", "filament_cooling_final_speed", "filament_ramming_parameters", "filament_minimal_purge_on_wipe_tower",
     "filament_multitool_ramming", "filament_multitool_ramming_volume", "filament_multitool_ramming_flow", 
+    "extrusion_regression_a", "extrusion_regression_b", "extrusion_regression_c", "extrusion_regression_show",
     "temperature", "idle_temperature", "first_layer_temperature", "bed_temperature", "first_layer_bed_temperature", "fan_always_on", "cooling", "min_fan_speed",
     "max_fan_speed", "bridge_fan_speed", "disable_fan_first_layers", "full_fan_speed_layer", "fan_below_layer_time", "slowdown_below_layer_time", "min_print_speed",
     "start_filament_gcode", "end_filament_gcode", "enable_dynamic_fan_speeds",

src/libslic3r/Print.cpp

@@ -109,6 +109,10 @@ bool Print::invalidate_state_by_config_options(const ConfigOptionResolver & /* n
         "extruder_colour",
         "extruder_offset",
         "extrusion_multiplier",
+        "extrusion_regression_a",
+        "extrusion_regression_b",
+        "extrusion_regression_c",
+        "extrusion_regression_show",
         "fan_always_on",
         "fan_below_layer_time",
         "full_fan_speed_layer",

src/libslic3r/PrintConfig.cpp

@@ -995,6 +995,34 @@ void PrintConfigDef::init_fff_params()
     def->mode = comAdvanced;
     def->set_default_value(new ConfigOptionFloats { 1. });
 
+    def = this->add("extrusion_regression_a", coFloats);
+    def->label = L("A factor");
+    def->tooltip = L("A factor (X^2) of quadratic polynomial");
+    def->sidetext = L("*X^2");
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionFloats { 0. });
+
+    def = this->add("extrusion_regression_b", coFloats);
+    def->label = L("B factor");
+    def->tooltip = L("B factor (X) of quadratic polynomial");
+    def->sidetext = L("*X+");
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionFloats { 0. });
+
+    def = this->add("extrusion_regression_c", coFloats);
+    def->label = L("C factor");
+    def->tooltip = L("C factor (constant) of quadratic polynomial");
+    def->sidetext = L("+");
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionFloats { 1. });
+
+    def = this->add("extrusion_regression_show", coBool);
+    def->label = L("Show commanded extrusion");
+    def->tooltip = L("Show extrusion amount that was sent to extruder motor. "
+                    "It exceeds expected amount to compensate underextrusion caused by gear slippage.");
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionBool { false });
+
     def = this->add("extrusion_width", coFloatOrPercent);
     def->label = L("Default extrusion width");
     def->category = L("Extrusion Width");
@@ -3515,6 +3543,7 @@ void PrintConfigDef::init_extruder_option_keys()
     // ConfigOptionFloats, ConfigOptionPercents, ConfigOptionBools, ConfigOptionStrings
     m_extruder_option_keys = {
         "nozzle_diameter", "min_layer_height", "max_layer_height", "extruder_offset",
+        "extrusion_regression_a", "extrusion_regression_b", "extrusion_regression_c","extrusion_regression_show",
         "retract_length", "retract_lift", "retract_lift_above", "retract_lift_below", "retract_speed", "deretract_speed",
         "retract_before_wipe", "retract_restart_extra", "retract_before_travel", "wipe",
         "travel_slope", "travel_max_lift", "travel_ramping_lift", "travel_lift_before_obstacle",

src/libslic3r/PrintConfig.hpp

@@ -749,6 +749,10 @@ PRINT_CONFIG_CLASS_DEFINE(
     ((ConfigOptionFloats,              travel_max_lift))
     ((ConfigOptionFloats,              travel_slope))
     ((ConfigOptionBools,               travel_lift_before_obstacle))
+    ((ConfigOptionFloats,              extrusion_regression_a))//x^2
+    ((ConfigOptionFloats,              extrusion_regression_b))//x
+    ((ConfigOptionFloats,              extrusion_regression_c))//c
+    ((ConfigOptionBool,                extrusion_regression_show))
     ((ConfigOptionPercents,            retract_before_wipe))
     ((ConfigOptionFloats,              retract_length))
     ((ConfigOptionFloats,              retract_length_toolchange))

src/slic3r/GUI/Tab.cpp

@@ -2255,6 +2255,12 @@ void TabFilament::build()
         };
         optgroup->append_line(line);
 
+        optgroup = page->new_optgroup(L("Non-linear extrusion"));
+        optgroup->append_single_option_line("extrusion_regression_c");
+        optgroup->append_single_option_line("extrusion_regression_b");
+        optgroup->append_single_option_line("extrusion_regression_a");
+        optgroup->append_single_option_line("extrusion_regression_show");
+
         optgroup = page->new_optgroup(L("Wipe tower parameters"));
         optgroup->append_single_option_line("filament_minimal_purge_on_wipe_tower");