Implement Small Area Infill Flow Compensation

* Use graph option type
* Disable small area flow compensation on first layer
  Reasoning: We do not want to affect the first layer's extrusion in any way, especially by underextruding it. Doing so might cause user confusion and/or adhesion issues.

inspired by OrcaSlicer
Credits:
- Graph adaptation: @supermerill
- OrcaSlicer port: @mjonuschat
- Original implementation: @Alexander-T-Moss

#4329

resources/ui_layout/default/print.ui

@@ -238,6 +238,10 @@ group:Advanced Infill options
 		setting:label_width$8:width$5:fill_smooth_distribution
 		setting:label_width$26:label$Spacing between ironing lines:width$5:sidetext_width$7:fill_smooth_width
 	end_line
+	line:Small Area Infill Flow Compensation (beta)
+		setting:label$_:sidetext_width$0:small_area_infill_flow_compensation
+		setting:label$_:small_area_infill_flow_compensation_model
+	end_line
 group:title_width$19:Ironing post-process (This will go on top of infills and perimeters)
 	line:Enable ironing post-process
 		setting:label$_:sidetext_width$0:ironing

resources/ui_layout/example/print.ui

@@ -214,6 +214,10 @@ group:Advanced Infill options
 		setting:label_width$8:width$5:fill_smooth_distribution
 		setting:label_width$26:label$Spacing between ironing lines:width$5:sidetext_width$7:fill_smooth_width
 	end_line
+	line:Small Area Infill Flow Compensation (beta)
+		setting:label$_:sidetext_width$0:small_area_infill_flow_compensation
+		setting:label_:small_area_infill_flow_compensation_model
+	end_line
 group:title_width$19:Ironing post-process (This will go on top of infills and perimeters)
 	line:Enable ironing post-process
 		setting:label$_:sidetext_width$0:ironing

src/libslic3r/Config.cpp

@@ -453,6 +453,25 @@ bool GraphData::deserialize(const std::string &str)
         this->begin_idx = 0;
         this->end_idx = this->graph_points.size();
         this->type = GraphType::SPLINE;
+    } else if (size_t pos = str.find(','); pos != std::string::npos) {
+        //maybe a coStrings with 0,0 values inside, like a coPoints but worse (used by orca's small_area_infill_flow_compensation_model)
+        std::vector<std::string> args;
+        boost::split(args, str, boost::is_any_of(","));
+        if (args.size() % 2 == 0) {
+            for (size_t i = 0; i < args.size(); i += 2) {
+                this->graph_points.emplace_back();
+                Vec2d &data_point = this->graph_points.back();
+                args[i].erase(std::remove(args[i].begin(), args[i].end(), '\n'), args[i].end());
+                args[i].erase(std::remove(args[i].begin(), args[i].end(), '"'), args[i].end());
+                data_point.x() = std::stod(args[i]);
+                args[i+1].erase(std::remove(args[i+1].begin(), args[i+1].end(), '\n'), args[i+1].end());
+                args[i+1].erase(std::remove(args[i+1].begin(), args[i+1].end(), '"'), args[i+1].end());
+                data_point.y() = std::stod(args[i+1]);
+            }
+        }
+        this->begin_idx = 0;
+        this->end_idx = this->graph_points.size();
+        this->type = GraphType::SPLINE;
     } else {
         std::istringstream iss(str);
         std::string              item;

src/libslic3r/Fill/Fill.cpp

@@ -86,7 +86,9 @@ struct SurfaceFillParams : FillParams
             RETURN_COMPARE_NON_EQUAL(config->gap_fill_acceleration);
             RETURN_COMPARE_NON_EQUAL(config->gap_fill_speed);
             RETURN_COMPARE_NON_EQUAL(config->print_extrusion_multiplier);
-            RETURN_COMPARE_NON_EQUAL(config->region_gcode.value);
+            RETURN_COMPARE_NON_EQUAL(config->region_gcode.value)
+            RETURN_COMPARE_NON_EQUAL(config->small_area_infill_flow_compensation.value)
+            RETURN_COMPARE_NON_EQUAL(config->small_area_infill_flow_compensation_model.value);
         }
         if (config == nullptr || rhs.config == nullptr || max_sparse_infill_spacing == 0)
             RETURN_COMPARE_NON_EQUAL(flow.width());
@@ -115,6 +117,8 @@ struct SurfaceFillParams : FillParams
             || config->gap_fill_speed != rhs.config->gap_fill_speed
             || config->print_extrusion_multiplier != rhs.config->print_extrusion_multiplier
             || config->region_gcode != rhs.config->region_gcode
+            || config->small_area_infill_flow_compensation != rhs.config->small_area_infill_flow_compensation
+            || config->small_area_infill_flow_compensation_model != rhs.config->small_area_infill_flow_compensation_model
             ))
             return false;
         // then check params

src/libslic3r/GCode.cpp

@@ -5595,16 +5595,40 @@ std::vector<double> cut_corner_cache = {
     0.252510726678311,0.262777267777188,0.27352986689699,0.284799648665007,0.296620441746888,0.309029079319231,0.322065740515038,0.335774339512048,0.350202970204428,0.365404415947691,
     0.381436735764648,0.398363940736199,0.416256777189962,0.435193636891737,0.455261618934834 };
 
-
-void GCode::_extrude_line(std::string& gcode_str, const Line& line, const double e_per_mm, const std::string& comment) {
+void GCode::_extrude_line(std::string& gcode_str, const Line& line, const double e_per_mm, const std::string& comment,
+                          ExtrusionRole role) {
     if (line.a.coincides_with_epsilon(line.b)) {
         assert(false); // todo: investigate if it happens (it happens in perimeters)
         return;
     }
+    std::string comment_copy = comment;
+    double unscaled_line_length = unscaled(line.length());
+    double extrusion_value = e_per_mm * unscaled_line_length;
+    // small_area_infill_flow_compensation
+    // this is only done in _extrude_line and not in _extrude_line_cut_corner because _extrude_line_cut_corner doesn't apply to solid infill, but only for external perimeters.
+    if (!this->on_first_layer() && (role == ExtrusionRole::erSolidInfill || role == ExtrusionRole::erTopSolidInfill) &&
+        m_config.small_area_infill_flow_compensation.value &&
+        m_config.small_area_infill_flow_compensation_model.value.data_size() > 1) {
+        GraphData graph = m_config.small_area_infill_flow_compensation_model.value;
+        assert(graph.begin_idx >= 0 && graph.begin_idx + 1 < graph.end_idx && graph.end_idx <= graph.graph_points.size());
+        // ensure it start at length = 0, and ensure it ends with a compensation of 1.
+        graph.graph_points[graph.begin_idx].x() = 0;
+        graph.graph_points[graph.end_idx - 1].y() = 1;
+        //interpolate and verify
+        double new_extrusion_value = extrusion_value * graph.interpolate(unscaled_line_length);
+        assert(new_extrusion_value > 0.0);
+        if (new_extrusion_value > 0.0 && new_extrusion_value != extrusion_value) {
+            extrusion_value = new_extrusion_value;
+            if (m_config.gcode_comments) {
+                comment_copy += Slic3r::format(_(L(" | Old Flow Value: %0.5f Length: %0.5f")), extrusion_value, unscaled_line_length);
+            }
+        }
+    }
+    // end small_area_infill_flow_compensation
     gcode_str += m_writer.extrude_to_xy(
         this->point_to_gcode(line.b),
-        e_per_mm * unscaled(line.length()),
-        comment);
+        extrusion_value,
+        comment_copy);
 }
 
 void GCode::_extrude_line_cut_corner(std::string& gcode_str, const Line& line, const double e_per_mm, const std::string& comment, Point& last_pos, const double path_width) {
@@ -5745,7 +5769,7 @@ std::string GCode::_extrude(const ExtrusionPath &path, const std::string &descri
             for (const Line& line : path.polyline.lines()) {
                 if (path.role() != erExternalPerimeter || config().external_perimeter_cut_corners.value == 0) {
                     // normal & legacy pathcode
-                    _extrude_line(gcode, line, e_per_mm, comment);
+                    _extrude_line(gcode, line, e_per_mm, comment, path.role());
                 } else {
                     _extrude_line_cut_corner(gcode, line, e_per_mm, comment, last_pos, path.width);
                 }
@@ -5763,7 +5787,7 @@ std::string GCode::_extrude(const ExtrusionPath &path, const std::string &descri
                         const Line line = Line(path.polyline.get_points()[point_index - 1], path.polyline.get_points()[point_index]);
                         if (path.role() != erExternalPerimeter || config().external_perimeter_cut_corners.value == 0) {
                             // normal & legacy pathcode
-                            _extrude_line(gcode, line, e_per_mm, comment);
+                            _extrude_line(gcode, line, e_per_mm, comment, path.role());
                         } else {
                             _extrude_line_cut_corner(gcode, line, e_per_mm, comment, last_pos, path.width);
                         }

src/libslic3r/GCode.hpp

@@ -519,7 +519,7 @@ class GCode : ExtrusionVisitorConst  {
 
     double compute_e_per_mm(double path_mm3_per_mm);
     std::string _extrude(const ExtrusionPath &path, const std::string &description, double speed = -1);
-    void _extrude_line(std::string& gcode_str, const Line& line, const double e_per_mm, const std::string& comment);
+    void _extrude_line(std::string& gcode_str, const Line& line, const double e_per_mm, const std::string& comment, ExtrusionRole role);
     void _extrude_line_cut_corner(std::string& gcode_str, const Line& line, const double e_per_mm, const std::string& comment, Point& last_pos, const double path_width);
     std::string _before_extrude(const ExtrusionPath &path, const std::string &description, double speed = -1);
     double_t    _compute_speed_mm_per_sec(const ExtrusionPath &path, double speed, std::string *comment);

src/libslic3r/Preset.cpp

@@ -679,6 +679,7 @@ static std::vector<std::string> s_Preset_print_options {
         "bridge_overlap_min",
         "first_layer_flow_ratio",
         "clip_multipart_objects", "enforce_full_fill_volume", "external_infill_margin", "bridged_infill_margin",
+        "small_area_infill_flow_compensation", "small_area_infill_flow_compensation_model",
         // compensation
         "first_layer_size_compensation",
         "first_layer_size_compensation_layers",
@@ -737,7 +738,7 @@ static std::vector<std::string> s_Preset_print_options {
         "milling_speed",
         //Arachne
         "perimeter_generator", "wall_transition_length", "wall_transition_filter_deviation", "wall_transition_angle",
-        "wall_distribution_count", "min_feature_size", "min_bead_width"
+        "wall_distribution_count", "min_feature_size", "min_bead_width",
 };
 
 static std::vector<std::string> s_Preset_filament_options {

src/libslic3r/PrintConfig.cpp

@@ -2510,6 +2510,42 @@ void PrintConfigDef::init_fff_params()
     def->sidetext = L("%");
     def->set_default_value(new ConfigOptionPercent(10));
 
+    def = this->add("small_area_infill_flow_compensation", coBool);
+    def->label = L("Enable small area flow compensation");
+    def->category = OptionCategory::infill;
+    def->tooltip = L("Enable flow compensation for small infill areas."
+                    "\nFirst layer is always disabled, to not compromise adhesion.");
+    def->mode = comExpert | comSuSi;
+    def->set_default_value(new ConfigOptionBool(false));
+
+    def = this->add("small_area_infill_flow_compensation_model", coGraph);
+    def->label = L("Flow Compensation Model");
+    def->category = OptionCategory::infill;
+    def->tooltip = L("Flow Compensation Model, used to adjust the flow for small solid infill "
+                     "lines. The model is a graph of flow correction factors (between 0 and 1) per extrusion length (in mm)."
+                     "\nThe first point length has to be 0mm. the last point need to have a flow correction of 1.");
+    def->mode = comExpert | comSuSi;
+    def->set_default_value(new ConfigOptionGraph(GraphData(0,10, GraphData::GraphType::SPLINE,
+        {{0,0},{0.2,0.44},{0.4,0.61},{0.6,0.7},{0.8,0.76},{1.5,0.86},{2,0.89},{3,0.92},{5,0.95},{10,1}}
+    )));
+    def->graph_settings = std::make_shared<GraphSettings>();
+    def->graph_settings->title       = L("Flow Compensation Model");
+    def->graph_settings->description = def->tooltip;
+    def->graph_settings->x_label     = L("Length of an extrusion (mm)");
+    def->graph_settings->y_label     = L("Flow correction (ratio between 0 and 1)");
+    def->graph_settings->null_label  = L("No values");
+    def->graph_settings->label_min_x = "";
+    def->graph_settings->label_max_x = L("Maximum length");
+    def->graph_settings->label_min_y = L("Minimum ratio");
+    def->graph_settings->label_max_y = L("Maximum ratio");
+    def->graph_settings->min_x       = 0;
+    def->graph_settings->max_x       = 100;
+    def->graph_settings->step_x      = 0.1;
+    def->graph_settings->min_y       = 0;
+    def->graph_settings->max_y       = 1;
+    def->graph_settings->step_y      = 0.01;
+    def->graph_settings->allowed_types = {GraphData::GraphType::LINEAR, GraphData::GraphType::SPLINE, GraphData::GraphType::SQUARE};
+
     def = this->add("first_layer_acceleration", coFloatOrPercent);
     def->label = L("Max");
     def->full_label = L("First layer acceleration");
@@ -8467,6 +8503,8 @@ std::unordered_set<std::string> prusa_export_to_remove_keys = {
 "skirt_brim",
 "skirt_distance_from_brim",
 "skirt_extrusion_width",
+"small_area_infill_flow_compensation",
+"small_area_infill_flow_compensation_model",
 "small_perimeter_max_length",
 "small_perimeter_min_length",
 "solid_fill_pattern",

src/libslic3r/PrintConfig.hpp

@@ -952,6 +952,8 @@ PRINT_CONFIG_CLASS_DEFINE(
     ((ConfigOptionFloat,                print_retract_length))
     ((ConfigOptionFloat,                print_retract_lift))
     ((ConfigOptionString,               region_gcode))
+    ((ConfigOptionBool,                 small_area_infill_flow_compensation))
+    ((ConfigOptionGraph,                small_area_infill_flow_compensation_model))
     ((ConfigOptionFloatOrPercent,       small_perimeter_speed))
     ((ConfigOptionFloatOrPercent,       small_perimeter_min_length))
     ((ConfigOptionFloatOrPercent,       small_perimeter_max_length))

src/libslic3r/PrintObject.cpp

@@ -1031,6 +1031,8 @@ FillLightning::GeneratorPtr PrintObject::prepare_lightning_infill_data()
                 || opt_key == "seam_notch_outer"
                 || opt_key == "seam_travel_cost"
                 || opt_key == "seam_visibility"
+                || opt_key == "small_area_infill_flow_compensation"
+                || opt_key == "small_area_infill_flow_compensation_model"
                 || opt_key == "small_perimeter_speed"
                 || opt_key == "small_perimeter_min_length"
                 || opt_key == "small_perimeter_max_length"

src/slic3r/GUI/ConfigManipulation.cpp

@@ -434,6 +434,11 @@ void ConfigManipulation::toggle_print_fff_options(DynamicPrintConfig* config)
 
     toggle_field("fill_angle", (have_infill || has_solid_infill) && ((ConfigOptionVectorBase*)config->option("fill_angle_template"))->size() == 0);
 
+
+    toggle_field("small_area_infill_flow_compensation", has_solid_infill);
+    bool have_small_area_infill_flow_compensation = has_solid_infill && config->opt_bool("small_area_infill_flow_compensation");
+    toggle_field("small_area_infill_flow_compensation_model", have_small_area_infill_flow_compensation);
+
     toggle_field("top_solid_min_thickness", ! has_spiral_vase && has_top_solid_infill);
     toggle_field("bottom_solid_min_thickness", ! has_spiral_vase && has_bottom_solid_infill);