Fix SPE-2068: Helical layer changes out of bed bounds.

src/libslic3r/GCode.cpp

@@ -2673,7 +2673,11 @@ Polygon Bed::get_inner_offset(const std::vector<Vec2d>& shape, const double padd
     transform(begin(shape), end(shape), back_inserter(shape_scaled), [](const Vec2d& point){
         return scaled(point);
     });
-    return shrink({Polygon{shape_scaled}}, scaled(padding)).front();
+    Polygons inner_offset{shrink({Polygon{shape_scaled}}, scaled(padding))};
+    if (inner_offset.empty()) {
+        return Polygon{};
+    }
+    return inner_offset.front();
 }
 }
 
@@ -2692,21 +2696,18 @@ std::optional<std::string> GCodeGenerator::get_helical_layer_change_gcode(
 
     const Point n_gon_start_point{this->last_pos()};
 
-    static GCode::Impl::Bed bed{
+    GCode::Impl::Bed bed{
         this->m_config.bed_shape.values,
-        circle_radius
+        circle_radius * 2
     };
     if (!bed.contains_within_padding(this->point_to_gcode(n_gon_start_point))) {
         return std::nullopt;
     }
 
-    const Point n_gon_centeroid{
-        n_gon_start_point
-        + scaled(Vec2d{
-            (bed.centroid - unscaled(n_gon_start_point)).normalized()
-            * circle_radius
-        })
-    };
+    const Vec2crd n_gon_vector{scaled(Vec2d{
+        (bed.centroid - this->point_to_gcode(n_gon_start_point)).normalized() * circle_radius
+    })};
+    const Point n_gon_centeroid{n_gon_start_point + n_gon_vector};
 
     const Polygon n_gon{GCode::Impl::generate_regular_polygon(
         n_gon_centeroid,