Scale emulated spiral Z-hop segments based on slicing resolution (#11556)

Spiral Z-Hop resolution

Use slicing resolution to determine segment count for emulated spiral Z-hop

What’s changed

The number of linear segments used to approximate a spiral Z-hop is now derived from the PrintConfig resolution value.

The segment count is clamped to a safe range (4–24) to avoid excessive G-code generation or MCU queue overflow.

Why

Previously a fixed 24 segments were always used, regardless of model resolution.

For small-radius spiral lifts this was excessive and could overwhelm some printers.

Adapting segment count to resolution ensures smooth motion where needed, but lighter G-code where possible.

Details

m_resolution is now stored via apply_print_config().

_spiral_travel_to_z() uses this value to compute segment count dynamically.

Only the linear-segment fallback path is affected; G2/G3 arc-fitting remains unchanged.

src/libslic3r/GCodeWriter.cpp

@@ -42,6 +42,7 @@ void GCodeWriter::apply_print_config(const PrintConfig &print_config)
     };
     m_max_jerk_z = print_config.machine_max_jerk_z.values.front();
     m_max_jerk_e = print_config.machine_max_jerk_e.values.front();
+    m_resolution = print_config.resolution.value;
 }
 
 void GCodeWriter::set_extruders(std::vector<unsigned int> extruder_ids)
@@ -787,8 +788,18 @@ std::string GCodeWriter::_spiral_travel_to_z(double z, const Vec2d &ij_offset, c
 
     if (!this->config.enable_arc_fitting) { // Orca: if arc fitting is disabled, approximate the arc with small linear segments
         std::ostringstream oss;
-        const double z_start = m_pos(2);                // starting Z height
+        const double z_start = m_pos(2); // starting Z height
-        const int segments = 24;                        // number of linear segments to use for approximating the arc
+
+        // --------------------------------------------------------------------
+        // Determine number of segments based on Resolution
+        // --------------------------------------------------------------------
+        const double ref_resolution = 0.01; // reference resolution in mm
+        const double ref_segments  = 16.0;  // reference number of segments at reference resolution
+        
+        // number of linear segments to use for approximating the arc, clamp between 4 and 24
+        const int segments = std::clamp(int(std::round(ref_segments * (ref_resolution / m_resolution))), 4, 24);
+        // --------------------------------------------------------------------
+
         const double px = m_pos(0) - m_x_offset;        // take plate offset into consideration
         const double py = m_pos(1) - m_y_offset;        // take plate offset into consideration
         const double cx = px + ij_offset(0);            // center x

src/libslic3r/GCodeWriter.hpp

@@ -168,6 +168,9 @@ public:
     //BBS: x, y offset for gcode generated
     double          m_x_offset{ 0 };
     double          m_y_offset{ 0 };
+
+    // Orca: slicing resolution in mm
+    double          m_resolution = 0.01;
     
     std::string m_gcode_label_objects_start;
     std::string m_gcode_label_objects_end;