Multimaterial purging lines fixed on rectangular beds with non-standard origin (#3805)

src/libslic3r/GCode.cpp

@@ -291,7 +291,7 @@ std::string WipeTowerIntegration::append_tcr(GCode &gcodegen, const WipeTower::T
 
     std::string gcode;
 
-    // Toolchangeresult.gcode assumes the wipe tower corner is at the origin
+    // Toolchangeresult.gcode assumes the wipe tower corner is at the origin (except for priming lines)
     // We want to rotate and shift all extrusions (gcode postprocessing) and starting and ending position
     float alpha = m_wipe_tower_rotation/180.f * float(M_PI);
     Vec2f start_pos = tcr.start_pos;

src/libslic3r/GCode/WipeTower.cpp

@@ -492,6 +492,9 @@ WipeTower::WipeTower(const PrintConfig& config, const std::vector<std::vector<fl
     const std::vector<Vec2d>& bed_points = config.bed_shape.values;
     m_bed_shape = (bed_points.size() == 4 ? RectangularBed : CircularBed);
     m_bed_width = float(BoundingBoxf(bed_points).size().x());
+    m_bed_bottom_left = m_bed_shape == RectangularBed
+                  ? Vec2f(bed_points.front().x(), bed_points.front().y())
+                  : Vec2f::Zero();
 }
 
 
@@ -566,6 +569,8 @@ std::vector<WipeTower::ToolChangeResult> WipeTower::prime(
     // In case of a circular bed, place it so it goes across the diameter and hope it will fit
     if (m_bed_shape == CircularBed)
         cleaning_box.translate(-m_bed_width/2 + m_bed_width * 0.03f, -m_bed_width * 0.12f);
+    if (m_bed_shape == RectangularBed)
+        cleaning_box.translate(m_bed_bottom_left);
 
     std::vector<ToolChangeResult> results;
 

src/libslic3r/GCode/WipeTower.hpp

@@ -236,6 +236,7 @@ private:
         CircularBed
     } m_bed_shape;
     float m_bed_width; // width of the bed bounding box
+    Vec2f m_bed_bottom_left; // bottom-left corner coordinates (for rectangular beds)
 
 	float m_perimeter_width = 0.4f * Width_To_Nozzle_Ratio; // Width of an extrusion line, also a perimeter spacing for 100% infill.
 	float m_extrusion_flow = 0.038f; //0.029f;// Extrusion flow is derived from m_perimeter_width, layer height and filament diameter.