Belt: remove dead code

belt_remapped_bbox() had no callers; belt_min_z() and
m_belt_global_xy_correction were written but never read;
LayerTools::has_belt_brim was set but never read; belt_surface_z was a
named zero.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

src/libslic3r/GCode/ToolOrdering.cpp

@@ -1023,7 +1023,6 @@ void ToolOrdering::collect_extruders(const PrintObject &object, const std::vecto
                 continue;
             LayerTools &layer_tools = this->tools_for_layer(band.print_z);
             layer_tools.extruders.push_back(brim_filament);
-            layer_tools.has_belt_brim = true;
         }
     }
 
@@ -1042,7 +1041,6 @@ void ToolOrdering::collect_extruders(const PrintObject &object, const std::vecto
                 continue;
             LayerTools &layer_tools = this->tools_for_layer(object.layers()[i]->print_z);
             layer_tools.extruders.push_back(brim_filament);
-            layer_tools.has_belt_brim = true;
         }
     }
 

src/libslic3r/GCode/ToolOrdering.hpp

@@ -179,10 +179,6 @@ public:
     // Should a skirt be printed at this layer?
     // Layers are marked for infinite skirt aka draft shield. Not all the layers have to be printed.
     bool                        has_skirt = false;
-    // Belt printers: is this one of the brim-only apron layers below the object's
-    // first layer?  Kept separate from has_object so skirt marking and wiping
-    // overrides are unaffected.
-    bool                        has_belt_brim = false;
     // Will there be anything extruded on this layer for the wipe tower?
     // Due to the support layers possibly interleaving the object layers,
     // wipe tower will be disabled for some support only layers.

src/libslic3r/Print.hpp

@@ -231,12 +231,6 @@ class ConstSupportLayerPtrsAdaptor : public ConstVectorOfPtrsAdaptor<SupportLaye
     ConstSupportLayerPtrsAdaptor(const SupportLayerPtrs *data) : ConstVectorOfPtrsAdaptor<SupportLayer>(data) {}
 };
 
-// The model's raw bounding box, in the frame the belt floor parameters refer to.
-inline BoundingBoxf3 belt_remapped_bbox(const ModelObject &model_object, const PrintConfig & /*config*/)
-{
-    return model_object.raw_bounding_box();
-}
-
 // Single instance of a PrintObject.
 // As multiple PrintObjects may be generated for a single ModelObject (their instances differ in rotation around Z),
 // ModelObject's instancess will be distributed among these multiple PrintObjects.
@@ -721,8 +715,6 @@ private:
     bool                                    m_belt_brim_pending { false };
     // Belt printer: min_z of mesh after belt shear (before Z-shift), for z_offset calc.
     double                                  m_belt_min_z { 0.0 };
-    // Belt printer: XY correction from global pre-slice mode, applied to G-code origin.
-    Vec2d                                   m_belt_global_xy_correction { Vec2d::Zero() };
     // Belt printer: exact belt_floor_z_shift computed during posSlice from a
     // vertex-level scan of the post-transform mesh.  Cached separately from
     // m_slicing_params so that rebuilding m_slicing_params on a non-belt-affecting
@@ -733,8 +725,6 @@ private:
     bool                                    m_belt_floor_z_shift_cache_valid { false };
 public:
     double belt_global_z_offset() const { return m_belt_global_z_offset; }
-    double belt_min_z() const { return m_belt_min_z; }
-    Vec2d  belt_global_xy_correction() const { return m_belt_global_xy_correction; }
 private:
 
 

src/libslic3r/PrintObjectSlice.cpp

@@ -902,7 +902,6 @@ void PrintObject::slice()
     // them.
     m_belt_min_z              = 0.;
     m_belt_global_z_offset    = 0.;
-    m_belt_global_xy_correction = Vec2d::Zero();
     this->clear_layers();
     m_layers = new_layers(this, generate_object_layers(m_slicing_params, layer_height_profile, m_config.precise_z_height.value));
     this->slice_volumes();
@@ -995,7 +994,6 @@ void PrintObject::slice()
             // couples slicer_z back into both machine_y and machine_z.  Compensating
             // layer.print_z by belt_z_shift here makes the back-transform produce
             // correct machine-frame coordinates whether or not a global mode is active.
-            const double belt_surface_z = 0.;   // the belt surface is Z=0 in centered slicer space
             // The compensation must mirror the Z-shift actually applied, which
             // is max(0, -m_belt_min_z): when the transformed mesh starts ABOVE
             // slicer Z=0 (m_belt_min_z > 0 — possible for counter-rotated or
@@ -1003,7 +1001,7 @@ void PrintObject::slice()
             // no lift was applied, and an unclamped m_belt_min_z here would
             // leak straight into the layer Z values, floating the whole object
             // off the belt by exactly that amount.
-            double belt_z_shift = std::min(m_belt_min_z, 0.) - belt_surface_z;
+            double belt_z_shift = std::min(m_belt_min_z, 0.);   // the belt surface is Z=0 in centered slicer space
             double global_z_offset = belt_z_shift;
 
             // Centering correction: trafo_centered pretranslates by
@@ -1034,7 +1032,6 @@ void PrintObject::slice()
                 Vec3d d(unscale<double>(inst_shift.x()), unscale<double>(inst_shift.y()), 0.);
                 Vec3d c = T.linear() * d - d;
                 global_z_offset += c.z();
-                m_belt_global_xy_correction = Vec2d(c.x(), c.y());
 
                 BOOST_LOG_TRIVIAL(trace) << "Belt preslice_global: correction=("
                     << c.x() << ", " << c.y() << ", " << c.z() << ")"
@@ -1042,7 +1039,7 @@ void PrintObject::slice()
             }
 
             BOOST_LOG_TRIVIAL(trace) << "Belt global: z_offset=" << global_z_offset
-                << " (relative to min across " << this->print()->objects().size() << " objects)";
+                << " (" << this->print()->objects().size() << " objects on the plate)";
             m_belt_global_z_offset = global_z_offset;
             if (std::abs(global_z_offset) > EPSILON) {
                 for (Layer *layer : m_layers)