Scarf joint seam enhancement: conditional scarf joint and slowdown for scarf joint only (#4317)

* Allow apply scarf joint seams to perimeters without sharp corners only

* 1. Fix an error when detect whether a loop is smooth
2. Expose scarf_angle_threshold to UI

* fix linux build error

* minor code changes

* Support slowdown speed for scarf joint only

* update tips

* improve the logic a bit

* Fixed a bug that scarf speed may not respected for overhangs

* Add a new scarf flow ratio option

src/libslic3r/ExtrusionEntity.cpp

@@ -7,6 +7,7 @@
 #include <cmath>
 #include <limits>
 #include <sstream>
+#include "Utils.hpp"
 
 #define L(s) (s)
 
@@ -340,6 +341,65 @@ double ExtrusionLoop::min_mm3_per_mm() const
     return min_mm3_per_mm;
 }
 
+// Orca: This function is used to check if the loop is smooth(continuous) or not. 
+// TODO: the main logic is largly copied from the calculate_polygon_angles_at_vertices function in SeamPlacer file. Need to refactor the code in the future.
+bool ExtrusionLoop::is_smooth(double angle_threshold, double min_arm_length) const
+{
+    // go through all the points in the loop and check if the angle between two segments(AB and BC) is less than the threshold
+    size_t idx_prev = 0;
+    size_t idx_curr = 0;
+    size_t idx_next = 0;
+
+    float distance_to_prev = 0;
+    float distance_to_next = 0;
+
+    const auto _polygon = polygon();
+    const Points& points = _polygon.points;
+
+    std::vector<float> lengths{};
+    for (size_t point_idx = 0; point_idx < points.size() - 1; ++point_idx) {
+        lengths.push_back((unscale(points[point_idx]) - unscale(points[point_idx + 1])).norm());
+    }
+    lengths.push_back(std::max((unscale(points[0]) - unscale(points[points.size() - 1])).norm(), 0.1));
+
+    // push idx_prev far enough back as initialization
+    while (distance_to_prev < min_arm_length) {
+        idx_prev = Slic3r::prev_idx_modulo(idx_prev, points.size());
+        distance_to_prev += lengths[idx_prev];
+    }
+
+    for (size_t _i = 0; _i < points.size(); ++_i) {
+        // pull idx_prev to current as much as possible, while respecting the min_arm_length
+        while (distance_to_prev - lengths[idx_prev] > min_arm_length) {
+            distance_to_prev -= lengths[idx_prev];
+            idx_prev = Slic3r::next_idx_modulo(idx_prev, points.size());
+        }
+
+        // push idx_next forward as far as needed
+        while (distance_to_next < min_arm_length) {
+            distance_to_next += lengths[idx_next];
+            idx_next = Slic3r::next_idx_modulo(idx_next, points.size());
+        }
+
+        // Calculate angle between idx_prev, idx_curr, idx_next.
+        const Point& p0 = points[idx_prev];
+        const Point& p1 = points[idx_curr];
+        const Point& p2 = points[idx_next];
+        const auto a = angle(p0 - p1, p2 - p1);
+        if (a > 0 ? a < angle_threshold : a > -angle_threshold) {
+            return false;
+        }
+
+        // increase idx_curr by one
+        float curr_distance = lengths[idx_curr];
+        idx_curr++;
+        distance_to_prev += curr_distance;
+        distance_to_next -= curr_distance;
+    }
+
+    return true;
+}
+
 ExtrusionLoopSloped::ExtrusionLoopSloped(ExtrusionPaths&   original_paths,
                                          double            seam_gap,
                                          double            slope_min_length,

src/libslic3r/ExtrusionEntity.hpp

@@ -479,7 +479,8 @@ public:
             append(dst, p.polyline.points);
     }
     double total_volume() const override { double volume =0.; for (const auto& path : paths) volume += path.total_volume(); return volume; }
-
+    // check if the loop is smooth, angle_threshold is in radians, default is 10 degrees
+    bool is_smooth(double angle_threshold = 0.174, double min_arm_length = 0.025) const;
     //static inline std::string role_to_string(ExtrusionLoopRole role);
 
 #ifndef NDEBUG

src/libslic3r/GCode.cpp

@@ -4557,11 +4557,14 @@ std::string GCode::extrude_loop(ExtrusionLoop loop, std::string description, dou
         loop.split_at(last_pos, false);
 
     const auto seam_scarf_type = m_config.seam_slope_type.value;
-    const bool enable_seam_slope = ((seam_scarf_type == SeamScarfType::External && !is_hole) || seam_scarf_type == SeamScarfType::All) &&
+    bool enable_seam_slope = ((seam_scarf_type == SeamScarfType::External && !is_hole) || seam_scarf_type == SeamScarfType::All) &&
         !m_config.spiral_mode &&
         (loop.role() == erExternalPerimeter || (loop.role() == erPerimeter && m_config.seam_slope_inner_walls)) &&
         layer_id() > 0;
 
+    if (enable_seam_slope && m_config.seam_slope_conditional.value) {
+        enable_seam_slope = loop.is_smooth(m_config.scarf_angle_threshold.value * M_PI / 180., EXTRUDER_CONFIG(nozzle_diameter));
+    }
     // clip the path to avoid the extruder to get exactly on the first point of the loop;
     // if polyline was shorter than the clipping distance we'd get a null polyline, so
     // we discard it in that case
@@ -5068,6 +5071,8 @@ std::string GCode::_extrude(const ExtrusionPath &path, std::string description,
         _mm3_per_mm *= m_config.bottom_solid_infill_flow_ratio;
     else if (path.role() == erInternalBridgeInfill)
         _mm3_per_mm *= m_config.internal_bridge_flow;
+    else if(sloped)
+        _mm3_per_mm *= m_config.scarf_joint_flow_ratio;
 
 
     double e_per_mm = m_writer.extruder()->e_per_mm3() * _mm3_per_mm;
@@ -5082,6 +5087,10 @@ std::string GCode::_extrude(const ExtrusionPath &path, std::string description,
                 double new_speed = m_config.get_abs_value(overhang_speed_key_map[overhang_degree].c_str());
                 speed = new_speed == 0.0 ? speed : new_speed;
             }
+
+            if (sloped) {
+                speed = std::min(speed, m_config.scarf_joint_speed.get_abs_value(m_config.get_abs_value("inner_wall_speed")));
+            }
         } else if (path.role() == erExternalPerimeter) {
             speed = m_config.get_abs_value("outer_wall_speed");
             if (m_config.overhang_speed_classic.value && m_config.enable_overhang_speed.value &&
@@ -5089,6 +5098,9 @@ std::string GCode::_extrude(const ExtrusionPath &path, std::string description,
                 double new_speed = m_config.get_abs_value(overhang_speed_key_map[overhang_degree].c_str());
                 speed = new_speed == 0.0 ? speed : new_speed;
             }
+            if (sloped) {
+                speed = std::min(speed, m_config.scarf_joint_speed.get_abs_value(m_config.get_abs_value("outer_wall_speed")));
+            }
         } 
         else if(path.role() == erInternalBridgeInfill) {
             speed = m_config.get_abs_value("internal_bridge_speed");
@@ -5172,6 +5184,9 @@ std::string GCode::_extrude(const ExtrusionPath &path, std::string description,
         (is_bridge(path.role()) || is_perimeter(path.role()))) {
             bool is_external = is_external_perimeter(path.role());
             double ref_speed   = is_external ? m_config.get_abs_value("outer_wall_speed") : m_config.get_abs_value("inner_wall_speed");
+            if (sloped) {
+                ref_speed = std::min(ref_speed, m_config.scarf_joint_speed.get_abs_value(ref_speed));
+            }
             ConfigOptionPercents         overhang_overlap_levels({75, 50, 25, 13, 12.99, 0});
 
         	if (m_config.slowdown_for_curled_perimeters){
@@ -5235,6 +5250,10 @@ std::string GCode::_extrude(const ExtrusionPath &path, std::string description,
     }
 
     double F = speed * 60;  // convert mm/sec to mm/min
+    if(abs(F - 5753.504) < 0.002)
+    {
+        std::cout << "F: " << F << std::endl;
+    }
 
     //Orca: process custom gcode for extrusion role change
     if (path.role() != m_last_extrusion_role && !m_config.change_extrusion_role_gcode.value.empty()) {

src/libslic3r/Layer.cpp

@@ -186,6 +186,10 @@ void Layer::make_perimeters()
                         && config.fuzzy_skin_point_distance       == other_config.fuzzy_skin_point_distance
                         && config.fuzzy_skin_first_layer          == other_config.fuzzy_skin_first_layer
                         && config.seam_slope_type         == other_config.seam_slope_type
+                        && config.seam_slope_conditional == other_config.seam_slope_conditional
+                        && config.scarf_angle_threshold  == other_config.scarf_angle_threshold
+                        && config.scarf_joint_speed       == other_config.scarf_joint_speed
+                        && config.scarf_joint_flow_ratio       == other_config.scarf_joint_flow_ratio
                         && config.seam_slope_start_height == other_config.seam_slope_start_height
                         && config.seam_slope_entire_loop  == other_config.seam_slope_entire_loop
                         && config.seam_slope_min_length   == other_config.seam_slope_min_length

src/libslic3r/Preset.cpp

@@ -820,7 +820,7 @@ static std::vector<std::string> s_Preset_print_options {
      "wipe_tower_rotation_angle", "tree_support_branch_distance_organic", "tree_support_branch_diameter_organic", "tree_support_branch_angle_organic",
      "hole_to_polyhole", "hole_to_polyhole_threshold", "hole_to_polyhole_twisted", "mmu_segmented_region_max_width", "mmu_segmented_region_interlocking_depth",
      "small_area_infill_flow_compensation", "small_area_infill_flow_compensation_model",
-     "seam_slope_type", "seam_slope_start_height", "seam_slope_entire_loop", "seam_slope_min_length", "seam_slope_steps", "seam_slope_inner_walls",
+     "seam_slope_type", "seam_slope_conditional", "scarf_angle_threshold", "scarf_joint_speed", "scarf_joint_flow_ratio", "seam_slope_start_height", "seam_slope_entire_loop", "seam_slope_min_length", "seam_slope_steps", "seam_slope_inner_walls",
 };
 
 static std::vector<std::string> s_Preset_filament_options {

src/libslic3r/PrintConfig.cpp

@@ -3547,7 +3547,45 @@ def = this->add("filament_loading_speed", coFloats);
     def->enum_labels.push_back(L("Contour and hole"));
     def->mode = comAdvanced;
     def->set_default_value(new ConfigOptionEnum<SeamScarfType>(SeamScarfType::None));
-    
+
+    def = this->add("seam_slope_conditional", coBool);
+    def->label = L("Conditional scarf joint");
+    def->tooltip = L("Apply scarf joints only to smooth perimeters where traditional seams do not conceal the seams at sharp corners effectively.");
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionBool(false));
+
+    def = this->add("scarf_angle_threshold", coInt);
+    def->label = L("Conditional angle threshold");
+    def->tooltip = L(
+        "This option sets the threshold angle for applying a conditional scarf joint seam.\nIf the maximum angle within the perimeter loop "
+        "exceeds this value (indicating the absence of sharp corners), a scarf joint seam will be used. The default value is 155°.");
+    def->mode = comAdvanced;
+    def->sidetext = L("°");
+    def->min = 0;
+    def->max = 180;
+    def->set_default_value(new ConfigOptionInt(155));
+
+    def = this->add("scarf_joint_speed", coFloatOrPercent);
+    def->label = L("Scarf joint speed");
+    def->category = L("Quality");
+    def->tooltip  = L(
+        "This option sets the printing speed for scarf joints. It is recommended to print scarf joints at a slow speed (less than 100 "
+         "mm/s).  It's also advisable to enable 'Extrusion rate smoothing' if the set speed varies significantly from the speed of the "
+         "outer or inner walls. If the speed specified here is higher than the speed of the outer or inner walls, the printer will default "
+         "to the slower of the two speeds. When specified as a percentage (e.g., 80%), the speed is calculated based on the respective "
+         "outer or inner wall speed. The default value is set to 100%.");
+    def->sidetext = L("mm/s or %");
+    def->min = 1;
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionFloatOrPercent(100, true));
+
+    def = this->add("scarf_joint_flow_ratio", coFloat);
+    def->label = L("Scarf joint flow ratio");
+    def->tooltip = L("This factor affects the amount of material for scarf joints.");
+    def->mode = comAdvanced;
+    def->max = 2;
+    def->set_default_value(new ConfigOptionFloat(1));
+
     def = this->add("seam_slope_start_height", coFloatOrPercent);
     def->label = L("Scarf start height");
     def->tooltip = L("Start height of the scarf.\n"

src/libslic3r/PrintConfig.hpp

@@ -953,11 +953,17 @@ PRINT_CONFIG_CLASS_DEFINE(
 
     // Orca: seam slopes
     ((ConfigOptionEnum<SeamScarfType>,  seam_slope_type))
+    ((ConfigOptionBool,                 seam_slope_conditional))
+    ((ConfigOptionInt,                  scarf_angle_threshold))
     ((ConfigOptionFloatOrPercent,       seam_slope_start_height))
     ((ConfigOptionBool,                 seam_slope_entire_loop))
     ((ConfigOptionFloat,                seam_slope_min_length))
     ((ConfigOptionInt,                  seam_slope_steps))
     ((ConfigOptionBool,                 seam_slope_inner_walls))
+    ((ConfigOptionFloatOrPercent,       scarf_joint_speed))
+    ((ConfigOptionFloat,                scarf_joint_flow_ratio))
+
+
 )
 
 PRINT_CONFIG_CLASS_DEFINE(

src/libslic3r/PrintObject.cpp

@@ -1143,6 +1143,10 @@ bool PrintObject::invalidate_state_by_config_options(
         } else if (
                opt_key == "seam_position"
             || opt_key == "seam_slope_type"
+            || opt_key == "seam_slope_conditional"
+            || opt_key == "scarf_angle_threshold"
+            || opt_key == "scarf_joint_speed"
+            || opt_key == "scarf_joint_flow_ratio"
             || opt_key == "seam_slope_start_height"
             || opt_key == "seam_slope_entire_loop"
             || opt_key == "seam_slope_min_length"

src/slic3r/GUI/ConfigManipulation.cpp

@@ -756,12 +756,16 @@ void ConfigManipulation::toggle_print_fff_options(DynamicPrintConfig *config, co
     
     toggle_field("seam_slope_type", !has_spiral_vase);
     bool has_seam_slope = !has_spiral_vase && config->opt_enum<SeamScarfType>("seam_slope_type") != SeamScarfType::None;
+    toggle_line("seam_slope_conditional", has_seam_slope);
     toggle_line("seam_slope_start_height", has_seam_slope);
     toggle_line("seam_slope_entire_loop", has_seam_slope);
     toggle_line("seam_slope_min_length", has_seam_slope);
     toggle_line("seam_slope_steps", has_seam_slope);
     toggle_line("seam_slope_inner_walls", has_seam_slope);
+    toggle_line("scarf_joint_speed", has_seam_slope);
+    toggle_line("scarf_joint_flow_ratio", has_seam_slope);
     toggle_field("seam_slope_min_length", !config->opt_bool("seam_slope_entire_loop"));
+    toggle_line("scarf_angle_threshold", has_seam_slope && config->opt_bool("seam_slope_conditional"));
 }
 
 void ConfigManipulation::update_print_sla_config(DynamicPrintConfig* config, const bool is_global_config/* = false*/)

src/slic3r/GUI/Tab.cpp

@@ -1977,10 +1977,14 @@ void TabPrint::build()
         optgroup->append_single_option_line("staggered_inner_seams", "seam");
         optgroup->append_single_option_line("seam_gap","seam");
         optgroup->append_single_option_line("seam_slope_type", "seam#scarf-joint-seam");
+        optgroup->append_single_option_line("seam_slope_conditional", "seam#scarf-joint-seam");
+        optgroup->append_single_option_line("scarf_angle_threshold", "seam#scarf-joint-seam");
+        optgroup->append_single_option_line("scarf_joint_speed", "seam#scarf-joint-seam");
         optgroup->append_single_option_line("seam_slope_start_height", "seam#scarf-joint-seam");
         optgroup->append_single_option_line("seam_slope_entire_loop", "seam#scarf-joint-seam");
         optgroup->append_single_option_line("seam_slope_min_length", "seam#scarf-joint-seam");
         optgroup->append_single_option_line("seam_slope_steps", "seam#scarf-joint-seam");
+        optgroup->append_single_option_line("scarf_joint_flow_ratio", "seam#scarf-joint-seam");
         optgroup->append_single_option_line("seam_slope_inner_walls", "seam#scarf-joint-seam");
         optgroup->append_single_option_line("role_based_wipe_speed","seam");
         optgroup->append_single_option_line("wipe_speed", "seam");