CLIPPER_OFFSET_SCALE was made a power of two, the scaling functions

inside ClipperUtils are now using bit shifts instead of multiplication
by doubles, which makes the scaling precise.

Removed the scale parameter from all offset functions.

Modified the safety offset to calculate offset per polygon instead
of over all polygons at once. The old way was not safe and very slow,
sometimes this meant a kiss of death for supports for example.

lib/Slic3r/GUI/Plater/2D.pm

@@ -173,7 +173,7 @@ sub repaint {
             
             # if sequential printing is enabled and we have more than one object, draw clearance area
             if ($self->{config}->complete_objects && (map @{$_->instances}, @{$self->{model}->objects}) > 1) {
-                my ($clearance) = @{offset([$thumbnail->convex_hull], (scale($self->{config}->extruder_clearance_radius) / 2), 1, JT_ROUND, scale(0.1))};
+                my ($clearance) = @{offset([$thumbnail->convex_hull], (scale($self->{config}->extruder_clearance_radius) / 2), JT_ROUND, scale(0.1))};
                 $dc->SetPen($self->{clearance_pen});
                 $dc->SetBrush($self->{transparent_brush});
                 $dc->DrawPolygon($self->scaled_points_to_pixel($clearance, 1), 0, 0);
@@ -185,7 +185,7 @@ sub repaint {
     if (@{$self->{objects}} && $self->{config}->skirts) {
         my @points = map @{$_->contour}, map @$_, map @{$_->instance_thumbnails}, @{$self->{objects}};
         if (@points >= 3) {
-            my ($convex_hull) = @{offset([convex_hull(\@points)], scale max($self->{config}->brim_width + $self->{config}->skirt_distance), 1, JT_ROUND, scale(0.1))};
+            my ($convex_hull) = @{offset([convex_hull(\@points)], scale max($self->{config}->brim_width + $self->{config}->skirt_distance), JT_ROUND, scale(0.1))};
             $dc->SetPen($self->{skirt_pen});
             $dc->SetBrush($self->{transparent_brush});
             $dc->DrawPolygon($self->scaled_points_to_pixel($convex_hull, 1), 0, 0);

lib/Slic3r/Geometry/Clipper.pm

@@ -7,7 +7,7 @@ our @ISA = qw(Exporter);
 our @EXPORT_OK = qw(offset offset_ex
     diff_ex diff union_ex intersection_ex xor_ex JT_ROUND JT_MITER
     JT_SQUARE is_counter_clockwise union_pt offset2 offset2_ex
-    intersection intersection_pl diff_pl union CLIPPER_OFFSET_SCALE
+    intersection intersection_pl diff_pl union
     union_pt_chained diff_ppl intersection_ppl);
 
 1;

lib/Slic3r/Print.pm

@@ -276,7 +276,7 @@ sub make_skirt {
     my $distance = scale max($self->config->skirt_distance, $self->config->brim_width);
     for (my $i = $skirts; $i > 0; $i--) {
         $distance += scale $spacing;
-        my $loop = offset([$convex_hull], $distance, 1, JT_ROUND, scale(0.1))->[0];
+        my $loop = offset([$convex_hull], $distance, JT_ROUND, scale(0.1))->[0];
         my $eloop = Slic3r::ExtrusionLoop->new_from_paths(
             Slic3r::ExtrusionPath->new(
                 polyline        => Slic3r::Polygon->new(@$loop)->split_at_first_point,
@@ -369,7 +369,7 @@ sub make_brim {
         # -0.5 because islands are not represented by their centerlines
         # (first offset more, then step back - reverse order than the one used for 
         # perimeters because here we're offsetting outwards)
-        push @loops, @{offset2(\@islands, ($i + 0.5) * $flow->scaled_spacing, -1.0 * $flow->scaled_spacing, 100000, JT_SQUARE)};
+        push @loops, @{offset2(\@islands, ($i + 0.5) * $flow->scaled_spacing, -1.0 * $flow->scaled_spacing, JT_SQUARE)};
     }
     
     $self->brim->append(map Slic3r::ExtrusionLoop->new_from_paths(

lib/Slic3r/Print/Object.pm

@@ -7,7 +7,7 @@ use List::Util qw(min max sum first);
 use Slic3r::Flow ':roles';
 use Slic3r::Geometry qw(X Y Z PI scale unscale chained_path epsilon);
 use Slic3r::Geometry::Clipper qw(diff diff_ex intersection intersection_ex union union_ex 
-    offset offset_ex offset2 offset2_ex intersection_ppl CLIPPER_OFFSET_SCALE JT_MITER);
+    offset offset_ex offset2 offset2_ex intersection_ppl JT_MITER);
 use Slic3r::Print::State ':steps';
 use Slic3r::Surface ':types';
 
@@ -863,7 +863,7 @@ sub discover_horizontal_shells {
                         # and it's not wanted in a hollow print even if it would make sense when
                         # obeying the solid shell count option strictly (DWIM!)
                         my $margin = $neighbor_layerm->flow(FLOW_ROLE_EXTERNAL_PERIMETER)->scaled_width;
-                        my $regularized = offset2($new_internal_solid, -$margin, +$margin, CLIPPER_OFFSET_SCALE, JT_MITER, 5);
+                        my $regularized = offset2($new_internal_solid, -$margin, +$margin, JT_MITER, 5);
                         my $too_narrow = diff(
                             $new_internal_solid,
                             $regularized,
@@ -893,7 +893,7 @@ sub discover_horizontal_shells {
                         # have the same angle, so the next shell would be grown even more and so on.
                         my $too_narrow = diff(
                             $new_internal_solid,
-                            offset2($new_internal_solid, -$margin, +$margin, CLIPPER_OFFSET_SCALE, JT_MITER, 5),
+                            offset2($new_internal_solid, -$margin, +$margin, JT_MITER, 5),
                             1,
                         );
                         

lib/Slic3r/Print/SupportMaterial.pm

@@ -8,7 +8,7 @@ use Slic3r::ExtrusionPath ':roles';
 use Slic3r::Flow ':roles';
 use Slic3r::Geometry qw(epsilon scale scaled_epsilon PI rad2deg deg2rad convex_hull);
 use Slic3r::Geometry::Clipper qw(offset diff union union_ex intersection offset_ex offset2
-    intersection_pl offset2_ex diff_pl CLIPPER_OFFSET_SCALE JT_MITER JT_ROUND);
+    intersection_pl offset2_ex diff_pl JT_MITER JT_ROUND);
 use Slic3r::Surface ':types';
 
 has 'print_config'      => (is => 'rw', required => 1);
@@ -299,9 +299,8 @@ sub contact_area {
                             offset(
                                 $diff, 
                                 $_,
-                                CLIPPER_OFFSET_SCALE,
                                 JT_ROUND,
-                                scale(0.05)*CLIPPER_OFFSET_SCALE),
+                                scale(0.05)),
                             $slices_margin
                         );
                     }
@@ -584,9 +583,8 @@ sub generate_base_layers {
                         $fillet_radius_scaled, 
                         -$fillet_radius_scaled,
                         # Use a geometric offsetting for filleting.
-                        CLIPPER_OFFSET_SCALE,
                         JT_ROUND,
-                        0.2*$fillet_radius_scaled*CLIPPER_OFFSET_SCALE),
+                        0.2*$fillet_radius_scaled),
                     $trim_polygons,
                     0); # don't apply the safety offset.
             }

xs/src/libslic3r/ClipperUtils.cpp

@@ -9,8 +9,51 @@
 
 #include <Shiny/Shiny.h>
 
+// Factor to convert from coord_t (which is int32) to an int64 type used by the Clipper library
+// for general offsetting (the offset(), offset2(), offset_ex() functions) and for the safety offset,
+// which is optionally executed by other functions (union, intersection, diff).
+// By the way, is the scalling for offset needed at all?
+#define CLIPPER_OFFSET_POWER_OF_2 17
+// 2^17=131072
+#define CLIPPER_OFFSET_SCALE (1 << CLIPPER_OFFSET_POWER_OF_2)
+#define CLIPPER_OFFSET_SCALE_ROUNDING_DELTA ((1 << (CLIPPER_OFFSET_POWER_OF_2 - 1)) - 1)
+
 namespace Slic3r {
 
+#ifdef CLIPPER_UTILS_DEBUG
+bool clipper_export_enabled = false;
+// For debugging the Clipper library, for providing bug reports to the Clipper author.
+bool export_clipper_input_polygons_bin(const char *path, const ClipperLib::Paths &input_subject, const ClipperLib::Paths &input_clip)
+{
+	FILE *pfile = fopen(path, "wb");
+	if (pfile == NULL)
+		return false;
+
+	uint32_t sz = uint32_t(input_subject.size());
+	fwrite(&sz, 1, sizeof(sz), pfile);
+	for (size_t i = 0; i < input_subject.size(); ++i) {
+		const ClipperLib::Path &path = input_subject[i];
+		sz = uint32_t(path.size());
+		::fwrite(&sz, 1, sizeof(sz), pfile);
+		::fwrite(path.data(), sizeof(ClipperLib::IntPoint), sz, pfile);
+	}
+	sz = uint32_t(input_clip.size());
+	::fwrite(&sz, 1, sizeof(sz), pfile);
+	for (size_t i = 0; i < input_clip.size(); ++i) {
+		const ClipperLib::Path &path = input_clip[i];
+		sz = uint32_t(path.size());
+		::fwrite(&sz, 1, sizeof(sz), pfile);
+		::fwrite(path.data(), sizeof(ClipperLib::IntPoint), sz, pfile);
+	}
+	::fclose(pfile);
+	return true;
+
+err:
+	::fclose(pfile);
+	return false;
+}
+#endif /* CLIPPER_UTILS_DEBUG */
+
 //-----------------------------------------------------------
 // legacy code from Clipper documentation
 void AddOuterPolyNodeToExPolygons(ClipperLib::PolyNode& polynode, Slic3r::ExPolygons* expolygons)
@@ -120,37 +163,51 @@ Slic3rMultiPoints_to_ClipperPaths(const T &input, ClipperLib::Paths* output)
     }
 }
 
-void
+void scaleClipperPolygon(ClipperLib::Path &polygon)
-scaleClipperPolygon(ClipperLib::Path &polygon, const double scale)
 {
     PROFILE_FUNC();
-
     for (ClipperLib::Path::iterator pit = polygon.begin(); pit != polygon.end(); ++pit) {
-        //FIXME multiplication of int64_t by double!
+        pit->X <<= CLIPPER_OFFSET_POWER_OF_2;
-        // Replace by bit shifts?
+        pit->Y <<= CLIPPER_OFFSET_POWER_OF_2;
-        (*pit).X *= scale;
-        (*pit).Y *= scale;
     }
 }
 
-void
+void scaleClipperPolygons(ClipperLib::Paths &polygons)
-scaleClipperPolygons(ClipperLib::Paths &polygons, const double scale)
 {
     PROFILE_FUNC();
-
+    for (ClipperLib::Paths::iterator it = polygons.begin(); it != polygons.end(); ++it)
-    for (ClipperLib::Paths::iterator it = polygons.begin(); it != polygons.end(); ++it) {
         for (ClipperLib::Path::iterator pit = (*it).begin(); pit != (*it).end(); ++pit) {
-            //FIXME multiplication of int64_t by double!
+            pit->X <<= CLIPPER_OFFSET_POWER_OF_2;
-            // Replace by bit shifts?
+            pit->Y <<= CLIPPER_OFFSET_POWER_OF_2;
-            (*pit).X *= scale;
-            (*pit).Y *= scale;
         }
+}
+
+void unscaleClipperPolygon(ClipperLib::Path &polygon)
+{
+    PROFILE_FUNC();
+    for (ClipperLib::Path::iterator pit = polygon.begin(); pit != polygon.end(); ++pit) {
+        pit->X += CLIPPER_OFFSET_SCALE_ROUNDING_DELTA;
+        pit->Y += CLIPPER_OFFSET_SCALE_ROUNDING_DELTA;
+        pit->X >>= CLIPPER_OFFSET_POWER_OF_2;
+        pit->Y >>= CLIPPER_OFFSET_POWER_OF_2;
     }
 }
 
+void unscaleClipperPolygons(ClipperLib::Paths &polygons)
+{
+    PROFILE_FUNC();
+    for (ClipperLib::Paths::iterator it = polygons.begin(); it != polygons.end(); ++it)
+        for (ClipperLib::Path::iterator pit = (*it).begin(); pit != (*it).end(); ++pit) {
+            pit->X += CLIPPER_OFFSET_SCALE_ROUNDING_DELTA;
+            pit->Y += CLIPPER_OFFSET_SCALE_ROUNDING_DELTA;
+            pit->X >>= CLIPPER_OFFSET_POWER_OF_2;
+            pit->Y >>= CLIPPER_OFFSET_POWER_OF_2;
+        }
+}
+
 void
 offset(const Slic3r::Polygons &polygons, ClipperLib::Paths* retval, const float delta,
-    double scale, ClipperLib::JoinType joinType, double miterLimit)
+    ClipperLib::JoinType joinType, double miterLimit)
 {
     PROFILE_FUNC();
     // read input
@@ -158,12 +215,12 @@ offset(const Slic3r::Polygons &polygons, ClipperLib::Paths* retval, const float
     Slic3rMultiPoints_to_ClipperPaths(polygons, &input);
     
     // scale input
-    scaleClipperPolygons(input, scale);
+    scaleClipperPolygons(input);
     
     // perform offset
     ClipperLib::ClipperOffset co;
     if (joinType == jtRound) {
-        co.ArcTolerance = miterLimit;
+        co.ArcTolerance = miterLimit * double(CLIPPER_OFFSET_SCALE);
     } else {
         co.MiterLimit = miterLimit;
     }
@@ -173,20 +230,20 @@ offset(const Slic3r::Polygons &polygons, ClipperLib::Paths* retval, const float
     }
     {
         PROFILE_BLOCK(offset_Execute);
-        co.Execute(*retval, (delta*scale));
+        co.Execute(*retval, delta * float(CLIPPER_OFFSET_SCALE));
     }
     
     // unscale output
-    scaleClipperPolygons(*retval, 1/scale);
+    unscaleClipperPolygons(*retval);
 }
 
 void
 offset(const Slic3r::Polygons &polygons, Slic3r::Polygons* retval, const float delta,
-    double scale, ClipperLib::JoinType joinType, double miterLimit)
+    ClipperLib::JoinType joinType, double miterLimit)
 {
     // perform offset
     ClipperLib::Paths output;
-    offset(polygons, &output, delta, scale, joinType, miterLimit);
+    offset(polygons, &output, delta, joinType, miterLimit);
     
     // convert into ExPolygons
     ClipperPaths_to_Slic3rMultiPoints(output, retval);
@@ -194,45 +251,45 @@ offset(const Slic3r::Polygons &polygons, Slic3r::Polygons* retval, const float d
 
 Slic3r::Polygons
 offset(const Slic3r::Polygons &polygons, const float delta,
-    double scale, ClipperLib::JoinType joinType, double miterLimit)
+    ClipperLib::JoinType joinType, double miterLimit)
 {
     Slic3r::Polygons pp;
-    offset(polygons, &pp, delta, scale, joinType, miterLimit);
+    offset(polygons, &pp, delta, joinType, miterLimit);
     return pp;
 }
 
 void
 offset(const Slic3r::Polylines &polylines, ClipperLib::Paths* retval, const float delta,
-    double scale, ClipperLib::JoinType joinType, double miterLimit)
+    ClipperLib::JoinType joinType, double miterLimit)
 {
     // read input
     ClipperLib::Paths input;
     Slic3rMultiPoints_to_ClipperPaths(polylines, &input);
     
     // scale input
-    scaleClipperPolygons(input, scale);
+    scaleClipperPolygons(input);
     
     // perform offset
     ClipperLib::ClipperOffset co;
     if (joinType == jtRound) {
-        co.ArcTolerance = miterLimit;
+        co.ArcTolerance = miterLimit * double(CLIPPER_OFFSET_SCALE);
     } else {
         co.MiterLimit = miterLimit;
     }
     co.AddPaths(input, joinType, ClipperLib::etOpenButt);
-    co.Execute(*retval, (delta*scale));
+    co.Execute(*retval, delta * float(CLIPPER_OFFSET_SCALE));
     
     // unscale output
-    scaleClipperPolygons(*retval, 1/scale);
+    unscaleClipperPolygons(*retval);
 }
 
 void
 offset(const Slic3r::Polylines &polylines, Slic3r::Polygons* retval, const float delta,
-    double scale, ClipperLib::JoinType joinType, double miterLimit)
+    ClipperLib::JoinType joinType, double miterLimit)
 {
     // perform offset
     ClipperLib::Paths output;
-    offset(polylines, &output, delta, scale, joinType, miterLimit);
+    offset(polylines, &output, delta, joinType, miterLimit);
     
     // convert into ExPolygons
     ClipperPaths_to_Slic3rMultiPoints(output, retval);
@@ -240,11 +297,11 @@ offset(const Slic3r::Polylines &polylines, Slic3r::Polygons* retval, const float
 
 void
 offset(const Slic3r::Surface &surface, Slic3r::Surfaces* retval, const float delta,
-    double scale, ClipperLib::JoinType joinType, double miterLimit)
+    ClipperLib::JoinType joinType, double miterLimit)
 {
     // perform offset
     Slic3r::ExPolygons expp;
-    offset(surface.expolygon, &expp, delta, scale, joinType, miterLimit);
+    offset(surface.expolygon, &expp, delta, joinType, miterLimit);
     
     // clone the input surface for each expolygon we got
     retval->clear();
@@ -258,11 +315,11 @@ offset(const Slic3r::Surface &surface, Slic3r::Surfaces* retval, const float del
 
 void
 offset(const Slic3r::Polygons &polygons, Slic3r::ExPolygons* retval, const float delta,
-    double scale, ClipperLib::JoinType joinType, double miterLimit)
+    ClipperLib::JoinType joinType, double miterLimit)
 {
     // perform offset
     ClipperLib::Paths output;
-    offset(polygons, &output, delta, scale, joinType, miterLimit);
+    offset(polygons, &output, delta, joinType, miterLimit);
     
     // convert into ExPolygons
     ClipperPaths_to_Slic3rExPolygons(output, retval);
@@ -272,19 +329,19 @@ offset(const Slic3r::Polygons &polygons, Slic3r::ExPolygons* retval, const float
 // a single polygon with multiple non-overlapping holes.
 // Each contour and hole is offsetted separately, then the holes are subtracted from the outer contours.
 void offset(const Slic3r::ExPolygon &expolygon, ClipperLib::Paths* retval, const float delta,
-    double scale, ClipperLib::JoinType joinType, double miterLimit)
+    ClipperLib::JoinType joinType, double miterLimit)
 {
 //    printf("new ExPolygon offset\n");
     // 1) Offset the outer contour.
-    const float delta_scaled = float(delta * scale);
+    const float delta_scaled = delta * float(CLIPPER_OFFSET_SCALE);
     ClipperLib::Paths contours;
     {
         ClipperLib::Path input;
         Slic3rMultiPoint_to_ClipperPath(expolygon.contour, &input);
-        scaleClipperPolygon(input, scale);
+        scaleClipperPolygon(input);
         ClipperLib::ClipperOffset co;
         if (joinType == jtRound)
-            co.ArcTolerance = miterLimit;
+            co.ArcTolerance = miterLimit * double(CLIPPER_OFFSET_SCALE);
         else
             co.MiterLimit = miterLimit;
         co.AddPath(input, joinType, ClipperLib::etClosedPolygon);
@@ -298,10 +355,10 @@ void offset(const Slic3r::ExPolygon &expolygon, ClipperLib::Paths* retval, const
         for (Polygons::const_iterator it_hole = expolygon.holes.begin(); it_hole != expolygon.holes.end(); ++ it_hole) {
             ClipperLib::Path input;
             Slic3rMultiPoint_to_ClipperPath_reversed(*it_hole, &input);
-            scaleClipperPolygon(input, scale);
+            scaleClipperPolygon(input);
             ClipperLib::ClipperOffset co;
             if (joinType == jtRound)
-                co.ArcTolerance = miterLimit;
+                co.ArcTolerance = miterLimit * double(CLIPPER_OFFSET_SCALE);
             else
                 co.MiterLimit = miterLimit;
             co.AddPath(input, joinType, ClipperLib::etClosedPolygon);
@@ -322,15 +379,15 @@ void offset(const Slic3r::ExPolygon &expolygon, ClipperLib::Paths* retval, const
     }
     
     // 4) Unscale the output.
-    scaleClipperPolygons(*retval, 1/scale);
+    unscaleClipperPolygons(*retval);
 }
 
 Slic3r::Polygons offset(const Slic3r::ExPolygon &expolygon, const float delta,
-    double scale, ClipperLib::JoinType joinType, double miterLimit)
+    ClipperLib::JoinType joinType, double miterLimit)
 {
     // perform offset
     ClipperLib::Paths output;
-    offset(expolygon, &output, delta, scale, joinType, miterLimit);
+    offset(expolygon, &output, delta, joinType, miterLimit);
     
     // convert into ExPolygons
     Slic3r::Polygons retval;
@@ -339,11 +396,11 @@ Slic3r::Polygons offset(const Slic3r::ExPolygon &expolygon, const float delta,
 }
 
 Slic3r::ExPolygons offset_ex(const Slic3r::ExPolygon &expolygon, const float delta,
-    double scale, ClipperLib::JoinType joinType, double miterLimit)
+    ClipperLib::JoinType joinType, double miterLimit)
 {
     // perform offset
     ClipperLib::Paths output;
-    offset(expolygon, &output, delta, scale, joinType, miterLimit);
+    offset(expolygon, &output, delta, joinType, miterLimit);
     
     // convert into ExPolygons
     Slic3r::ExPolygons retval;
@@ -355,10 +412,10 @@ Slic3r::ExPolygons offset_ex(const Slic3r::ExPolygon &expolygon, const float del
 // a single polygon with multiple non-overlapping holes.
 // Each contour and hole is offsetted separately, then the holes are subtracted from the outer contours.
 void offset(const Slic3r::ExPolygons &expolygons, ClipperLib::Paths* retval, const float delta,
-    double scale, ClipperLib::JoinType joinType, double miterLimit)
+    ClipperLib::JoinType joinType, double miterLimit)
 {
 //    printf("new ExPolygon offset\n");
-    const float delta_scaled = float(delta * scale);
+    const float delta_scaled = delta * float(CLIPPER_OFFSET_SCALE);
     ClipperLib::Paths contours;
     ClipperLib::Paths holes;
     contours.reserve(expolygons.size());
@@ -374,10 +431,10 @@ void offset(const Slic3r::ExPolygons &expolygons, ClipperLib::Paths* retval, con
         {
             ClipperLib::Path input;
             Slic3rMultiPoint_to_ClipperPath(it_expoly->contour, &input);
-            scaleClipperPolygon(input, scale);
+            scaleClipperPolygon(input);
             ClipperLib::ClipperOffset co;
             if (joinType == jtRound)
-                co.ArcTolerance = miterLimit;
+                co.ArcTolerance = miterLimit * double(CLIPPER_OFFSET_SCALE);
             else
                 co.MiterLimit = miterLimit;
             co.AddPath(input, joinType, ClipperLib::etClosedPolygon);
@@ -391,10 +448,10 @@ void offset(const Slic3r::ExPolygons &expolygons, ClipperLib::Paths* retval, con
             for (Polygons::const_iterator it_hole = it_expoly->holes.begin(); it_hole != it_expoly->holes.end(); ++ it_hole) {
                 ClipperLib::Path input;
                 Slic3rMultiPoint_to_ClipperPath_reversed(*it_hole, &input);
-                scaleClipperPolygon(input, scale);
+                scaleClipperPolygon(input);
                 ClipperLib::ClipperOffset co;
                 if (joinType == jtRound)
-                    co.ArcTolerance = miterLimit;
+                    co.ArcTolerance = miterLimit * double(CLIPPER_OFFSET_SCALE);
                 else
                     co.MiterLimit = miterLimit;
                 co.AddPath(input, joinType, ClipperLib::etClosedPolygon);
@@ -416,15 +473,15 @@ void offset(const Slic3r::ExPolygons &expolygons, ClipperLib::Paths* retval, con
     }
     
     // 4) Unscale the output.
-    scaleClipperPolygons(*retval, 1/scale);
+    unscaleClipperPolygons(*retval);
 }
 
 Slic3r::Polygons offset(const Slic3r::ExPolygons &expolygons, const float delta,
-    double scale, ClipperLib::JoinType joinType, double miterLimit)
+    ClipperLib::JoinType joinType, double miterLimit)
 {
     // perform offset
     ClipperLib::Paths output;
-    offset(expolygons, &output, delta, scale, joinType, miterLimit);
+    offset(expolygons, &output, delta, joinType, miterLimit);
     
     // convert into ExPolygons
     Slic3r::Polygons retval;
@@ -433,11 +490,11 @@ Slic3r::Polygons offset(const Slic3r::ExPolygons &expolygons, const float delta,
 }
 
 Slic3r::ExPolygons offset_ex(const Slic3r::ExPolygons &expolygons, const float delta,
-    double scale, ClipperLib::JoinType joinType, double miterLimit)
+    ClipperLib::JoinType joinType, double miterLimit)
 {
     // perform offset
     ClipperLib::Paths output;
-    offset(expolygons, &output, delta, scale, joinType, miterLimit);
+    offset(expolygons, &output, delta, joinType, miterLimit);
     
     // convert into ExPolygons
     Slic3r::ExPolygons retval;
@@ -447,20 +504,20 @@ Slic3r::ExPolygons offset_ex(const Slic3r::ExPolygons &expolygons, const float d
 
 Slic3r::ExPolygons
 offset_ex(const Slic3r::Polygons &polygons, const float delta,
-    double scale, ClipperLib::JoinType joinType, double miterLimit)
+    ClipperLib::JoinType joinType, double miterLimit)
 {
     Slic3r::ExPolygons expp;
-    offset(polygons, &expp, delta, scale, joinType, miterLimit);
+    offset(polygons, &expp, delta, joinType, miterLimit);
     return expp;
 }
 
 void
 offset2(const Slic3r::Polygons &polygons, ClipperLib::Paths* retval, const float delta1,
-    const float delta2, const double scale, const ClipperLib::JoinType joinType, const double miterLimit)
+    const float delta2, const ClipperLib::JoinType joinType, const double miterLimit)
 {
     if (delta1 * delta2 >= 0) {
         // Both deltas are the same signum
-        offset(polygons, retval, delta1 + delta2, scale, joinType, miterLimit);
+        offset(polygons, retval, delta1 + delta2, joinType, miterLimit);
         return;
     }
 #ifdef CLIPPER_UTILS_DEBUG
@@ -479,12 +536,12 @@ offset2(const Slic3r::Polygons &polygons, ClipperLib::Paths* retval, const float
     Slic3rMultiPoints_to_ClipperPaths(polygons, &input);
     
     // scale input
-    scaleClipperPolygons(input, scale);
+    scaleClipperPolygons(input);
     
     // prepare ClipperOffset object
     ClipperLib::ClipperOffset co;
     if (joinType == jtRound) {
-        co.ArcTolerance = miterLimit;
+        co.ArcTolerance = miterLimit * double(CLIPPER_OFFSET_SCALE);
     } else {
         co.MiterLimit = miterLimit;
     }
@@ -492,30 +549,30 @@ offset2(const Slic3r::Polygons &polygons, ClipperLib::Paths* retval, const float
     // perform first offset
     ClipperLib::Paths output1;
     co.AddPaths(input, joinType, ClipperLib::etClosedPolygon);
-    co.Execute(output1, (delta1*scale));
+    co.Execute(output1, delta1 * float(CLIPPER_OFFSET_SCALE));
 #ifdef CLIPPER_UTILS_DEBUG
-    svg.draw(output1, 1./CLIPPER_OFFSET_SCALE, "red", stroke_width);
+    svg.draw(output1, 1. / double(CLIPPER_OFFSET_SCALE), "red", stroke_width);
 #endif /* CLIPPER_UTILS_DEBUG */
     
     // perform second offset
     co.Clear();
     co.AddPaths(output1, joinType, ClipperLib::etClosedPolygon);
-    co.Execute(*retval, (delta2*scale));
+    co.Execute(*retval, delta2 * float(CLIPPER_OFFSET_SCALE));
 #ifdef CLIPPER_UTILS_DEBUG
-    svg.draw(*retval, 1./CLIPPER_OFFSET_SCALE, "green", stroke_width);
+    svg.draw(*retval, 1. / double(CLIPPER_OFFSET_SCALE), "green", stroke_width);
 #endif /* CLIPPER_UTILS_DEBUG */
 
     // unscale output
-    scaleClipperPolygons(*retval, 1/scale);
+    unscaleClipperPolygons(*retval);
 }
 
 void
 offset2(const Slic3r::Polygons &polygons, Slic3r::Polygons* retval, const float delta1,
-    const float delta2, const double scale, const ClipperLib::JoinType joinType, const double miterLimit)
+    const float delta2, const ClipperLib::JoinType joinType, const double miterLimit)
 {
     // perform offset
     ClipperLib::Paths output;
-    offset2(polygons, &output, delta1, delta2, scale, joinType, miterLimit);
+    offset2(polygons, &output, delta1, delta2, joinType, miterLimit);
     
     // convert into ExPolygons
     ClipperPaths_to_Slic3rMultiPoints(output, retval);
@@ -523,20 +580,20 @@ offset2(const Slic3r::Polygons &polygons, Slic3r::Polygons* retval, const float
 
 Slic3r::Polygons
 offset2(const Slic3r::Polygons &polygons, const float delta1,
-    const float delta2, const double scale, const ClipperLib::JoinType joinType, const double miterLimit)
+    const float delta2, const ClipperLib::JoinType joinType, const double miterLimit)
 {
     Slic3r::Polygons pp;
-    offset2(polygons, &pp, delta1, delta2, scale, joinType, miterLimit);
+    offset2(polygons, &pp, delta1, delta2, joinType, miterLimit);
     return pp;
 }
 
 void
 offset2(const Slic3r::Polygons &polygons, Slic3r::ExPolygons* retval, const float delta1,
-    const float delta2, const double scale, const ClipperLib::JoinType joinType, const double miterLimit)
+    const float delta2, const ClipperLib::JoinType joinType, const double miterLimit)
 {
     // perform offset
     ClipperLib::Paths output;
-    offset2(polygons, &output, delta1, delta2, scale, joinType, miterLimit);
+    offset2(polygons, &output, delta1, delta2, joinType, miterLimit);
     
     // convert into ExPolygons
     ClipperPaths_to_Slic3rExPolygons(output, retval);
@@ -544,10 +601,10 @@ offset2(const Slic3r::Polygons &polygons, Slic3r::ExPolygons* retval, const floa
 
 Slic3r::ExPolygons
 offset2_ex(const Slic3r::Polygons &polygons, const float delta1,
-    const float delta2, const double scale, const ClipperLib::JoinType joinType, const double miterLimit)
+    const float delta2, const ClipperLib::JoinType joinType, const double miterLimit)
 {
     Slic3r::ExPolygons expp;
-    offset2(polygons, &expp, delta1, delta2, scale, joinType, miterLimit);
+    offset2(polygons, &expp, delta1, delta2, joinType, miterLimit);
     return expp;
 }
 
@@ -580,6 +637,13 @@ void _clipper_do(const ClipperLib::ClipType clipType, const Slic3r::Polygons &su
         PROFILE_BLOCK(_clipper_do_polygons_AddPaths);
         clipper.AddPaths(input_subject, ClipperLib::ptSubject, true);
         clipper.AddPaths(input_clip, ClipperLib::ptClip, true);
+
+#ifdef CLIPPER_UTILS_DEBUG
+        if (clipper_export_enabled) {
+            static int iRun = 0;
+			export_clipper_input_polygons_bin(debug_out_path("_clipper_do_polygons_AddPaths-polygons-%d", ++iRun).c_str(), input_subject, input_clip);
+        }
+#endif /* CLIPPER_UTILS_DEBUG */
     }
     
     // perform operation
@@ -986,22 +1050,39 @@ void safety_offset(ClipperLib::Paths* paths)
     PROFILE_FUNC();
 
     // scale input
-    scaleClipperPolygons(*paths, CLIPPER_OFFSET_SCALE);
+    scaleClipperPolygons(*paths);
     
     // perform offset (delta = scale 1e-05)
     ClipperLib::ClipperOffset co;
-    co.MiterLimit = 2;
+#ifdef CLIPPER_UTILS_DEBUG
-    {
+	if (clipper_export_enabled) {
-        PROFILE_BLOCK(safety_offset_AddPaths);
+		static int iRun = 0;
-        co.AddPaths(*paths, ClipperLib::jtMiter, ClipperLib::etClosedPolygon);
+		export_clipper_input_polygons_bin(debug_out_path("safety_offset-polygons-%d", ++iRun).c_str(), *paths, ClipperLib::Paths());
-    }
+	}
-    {
+#endif /* CLIPPER_UTILS_DEBUG */
-        PROFILE_BLOCK(safety_offset_Execute);
+    ClipperLib::Paths out;
-        co.Execute(*paths, 10.0 * CLIPPER_OFFSET_SCALE);
+    for (size_t i = 0; i < paths->size(); ++ i) {
+		co.Clear();
+        co.MiterLimit = 2;
+        {
+            PROFILE_BLOCK(safety_offset_AddPaths);
+            co.AddPath((*paths)[i], ClipperLib::jtMiter, ClipperLib::etClosedPolygon);
+        }
+        {
+            PROFILE_BLOCK(safety_offset_Execute);
+            // offset outside by 10um
+            ClipperLib::Paths out_this;
+            co.Execute(out_this, 10.f * float(CLIPPER_OFFSET_SCALE));
+            if (out.empty())
+                out = std::move(out_this);
+            else
+                std::move(std::begin(out_this), std::end(out_this), std::back_inserter(out));
+        }
     }
+    *paths = std::move(out);
     
     // unscale output
-    scaleClipperPolygons(*paths, 1.0/CLIPPER_OFFSET_SCALE);
+    unscaleClipperPolygons(*paths);
 }
 
 Polygons top_level_islands(const Slic3r::Polygons &polygons)

xs/src/libslic3r/ClipperUtils.hpp

@@ -14,13 +14,6 @@ using ClipperLib::jtSquare;
 
 namespace Slic3r {
 
-// Factor to convert from coord_t (which is int32) to an int64 type used by the Clipper library.
-//FIXME Vojtech: Better to use a power of 2 coefficient and to use bit shifts for scaling.
-// How about 2^17=131072?
-// By the way, is the scalling needed at all? Cura runs all the computation with a fixed point precision of 1um, while Slic3r scales to 1nm,
-// further scaling by 10e5 brings us to 
-#define CLIPPER_OFFSET_SCALE 100000.0
-
 //-----------------------------------------------------------
 // legacy code from Clipper documentation
 void AddOuterPolyNodeToExPolygons(ClipperLib::PolyNode& polynode, Slic3r::ExPolygons& expolygons);
@@ -40,29 +33,29 @@ void scaleClipperPolygons(ClipperLib::Paths &polygons, const double scale);
 
 // offset Polygons
 void offset(const Slic3r::Polygons &polygons, ClipperLib::Paths* retval, const float delta,
-    double scale = CLIPPER_OFFSET_SCALE, ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
+    ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
     double miterLimit = 3);
 void offset(const Slic3r::Polygons &polygons, Slic3r::Polygons* retval, const float delta,
-    double scale = CLIPPER_OFFSET_SCALE, ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
+    ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
     double miterLimit = 3);
 Slic3r::Polygons offset(const Slic3r::Polygons &polygons, const float delta,
-    double scale = CLIPPER_OFFSET_SCALE, ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
+    ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
     double miterLimit = 3);
 
 // This is a safe variant of the polygon offset, tailored for a single ExPolygon:
 // a single polygon with multiple non-overlapping holes.
 // Each contour and hole is offsetted separately, then the holes are subtracted from the outer contours.
 void offset(const Slic3r::ExPolygon &expolygon, ClipperLib::Paths* retval, const float delta,
-    double scale = CLIPPER_OFFSET_SCALE, ClipperLib::JoinType joinType = ClipperLib::jtMiter,
+    ClipperLib::JoinType joinType = ClipperLib::jtMiter,
     double miterLimit = 3);
 void offset(const Slic3r::ExPolygons &expolygons, ClipperLib::Paths* retval, const float delta,
-    double scale = CLIPPER_OFFSET_SCALE, ClipperLib::JoinType joinType = ClipperLib::jtMiter,
+    ClipperLib::JoinType joinType = ClipperLib::jtMiter,
     double miterLimit = 3);
 Slic3r::Polygons offset(const Slic3r::ExPolygon &expolygon, const float delta,
-    double scale = CLIPPER_OFFSET_SCALE, ClipperLib::JoinType joinType = ClipperLib::jtMiter,
+    ClipperLib::JoinType joinType = ClipperLib::jtMiter,
     double miterLimit = 3);
 Slic3r::Polygons offset(const Slic3r::ExPolygons &expolygons, const float delta,
-    double scale = CLIPPER_OFFSET_SCALE, ClipperLib::JoinType joinType = ClipperLib::jtMiter,
+    ClipperLib::JoinType joinType = ClipperLib::jtMiter,
     double miterLimit = 3);
 Slic3r::ExPolygons offset_ex(const Slic3r::ExPolygon &expolygon, const float delta,
     double scale, ClipperLib::JoinType joinType, double miterLimit);
@@ -71,36 +64,36 @@ Slic3r::ExPolygons offset_ex(const Slic3r::ExPolygons &expolygons, const float d
 
 // offset Polylines
 void offset(const Slic3r::Polylines &polylines, ClipperLib::Paths* retval, const float delta,
-    double scale = CLIPPER_OFFSET_SCALE, ClipperLib::JoinType joinType = ClipperLib::jtSquare, 
+    ClipperLib::JoinType joinType = ClipperLib::jtSquare, 
     double miterLimit = 3);
 void offset(const Slic3r::Polylines &polylines, Slic3r::Polygons* retval, const float delta,
-    double scale = CLIPPER_OFFSET_SCALE, ClipperLib::JoinType joinType = ClipperLib::jtSquare, 
+    ClipperLib::JoinType joinType = ClipperLib::jtSquare, 
     double miterLimit = 3);
 void offset(const Slic3r::Surface &surface, Slic3r::Surfaces* retval, const float delta,
-    double scale = CLIPPER_OFFSET_SCALE, ClipperLib::JoinType joinType = ClipperLib::jtSquare, 
+    ClipperLib::JoinType joinType = ClipperLib::jtSquare, 
     double miterLimit = 3);
 
 void offset(const Slic3r::Polygons &polygons, Slic3r::ExPolygons* retval, const float delta,
-    double scale = CLIPPER_OFFSET_SCALE, ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
+    ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
     double miterLimit = 3);
 Slic3r::ExPolygons offset_ex(const Slic3r::Polygons &polygons, const float delta,
-    double scale = CLIPPER_OFFSET_SCALE, ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
+    ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
     double miterLimit = 3);
 
 void offset2(const Slic3r::Polygons &polygons, ClipperLib::Paths* retval, const float delta1,
-    const float delta2, double scale = CLIPPER_OFFSET_SCALE, ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
+    const float delta2, ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
     double miterLimit = 3);
 void offset2(const Slic3r::Polygons &polygons, Slic3r::Polygons* retval, const float delta1,
-    const float delta2, double scale = CLIPPER_OFFSET_SCALE, ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
+    const float delta2, ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
     double miterLimit = 3);
 Slic3r::Polygons offset2(const Slic3r::Polygons &polygons, const float delta1,
-    const float delta2, double scale = CLIPPER_OFFSET_SCALE, ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
+    const float delta2, ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
     double miterLimit = 3);
 void offset2(const Slic3r::Polygons &polygons, Slic3r::ExPolygons* retval, const float delta1,
-    const float delta2, double scale = CLIPPER_OFFSET_SCALE, ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
+    const float delta2, ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
     double miterLimit = 3);
 Slic3r::ExPolygons offset2_ex(const Slic3r::Polygons &polygons, const float delta1,
-    const float delta2, double scale = CLIPPER_OFFSET_SCALE, ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
+    const float delta2, ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
     double miterLimit = 3);
 
 template <class T>

xs/src/libslic3r/Fill/FillRectilinear2.cpp

@@ -372,11 +372,9 @@ public:
         bool sticks_removed = remove_sticks(polygons_src);
 //        if (sticks_removed) printf("Sticks removed!\n");
         polygons_outer = offset(polygons_src, aoffset1,
-            CLIPPER_OFFSET_SCALE,
             ClipperLib::jtMiter,
             mitterLimit);
         polygons_inner = offset(polygons_outer, aoffset2 - aoffset1,
-            CLIPPER_OFFSET_SCALE,
             ClipperLib::jtMiter,
             mitterLimit);
 		// Filter out contours with zero area or small area, contours with 2 points only.

xs/src/libslic3r/LayerRegion.cpp

@@ -91,9 +91,9 @@ LayerRegion::make_perimeters(const SurfaceCollection &slices, SurfaceCollection*
     g.process();
 }
 
-//#define EXTERNAL_SURFACES_OFFSET_PARAMETERS CLIPPER_OFFSET_SCALE, ClipperLib::jtMiter, 3.
+//#define EXTERNAL_SURFACES_OFFSET_PARAMETERS ClipperLib::jtMiter, 3.
-//#define EXTERNAL_SURFACES_OFFSET_PARAMETERS CLIPPER_OFFSET_SCALE, ClipperLib::jtMiter, 1.5
+//#define EXTERNAL_SURFACES_OFFSET_PARAMETERS ClipperLib::jtMiter, 1.5
-#define EXTERNAL_SURFACES_OFFSET_PARAMETERS CLIPPER_OFFSET_SCALE, ClipperLib::jtSquare, 0.
+#define EXTERNAL_SURFACES_OFFSET_PARAMETERS ClipperLib::jtSquare, 0.
 
 void
 LayerRegion::process_external_surfaces(const Layer* lower_layer)
@@ -194,7 +194,7 @@ LayerRegion::process_external_surfaces(const Layer* lower_layer)
                         break;
                     }
                 // Grown by 3mm.
-                Polygons polys = offset(bridges[i].expolygon, float(margin), EXTERNAL_SURFACES_OFFSET_PARAMETERS);
+                Polygons polys = offset(to_polygons(bridges[i].expolygon), float(margin), EXTERNAL_SURFACES_OFFSET_PARAMETERS);
                 if (idx_island == -1) {
                     printf("Bridge did not fall into the source region!\r\n");
                 } else {

xs/src/libslic3r/Print.cpp

@@ -610,7 +610,7 @@ Print::validate() const
                 // grow convex hull with the clearance margin
                 {
                     Polygons grown_hull;
-                    offset(convex_hull, &grown_hull, scale_(this->config.extruder_clearance_radius.value)/2, 1, jtRound, scale_(0.1));
+                    offset(convex_hull, &grown_hull, scale_(this->config.extruder_clearance_radius.value)/2, jtRound, scale_(0.1));
                     convex_hull = grown_hull.front();
                 }
                 

xs/src/libslic3r/PrintObject.cpp

@@ -692,8 +692,7 @@ PrintObject::discover_vertical_shells()
 #if 1
             // Intentionally inflate a bit more than how much the region has been shrunk, 
             // so there will be some overlap between this solid infill and the other infill regions (mainly the sparse infill).
-            shell = offset2(shell, - 0.5f * min_perimeter_infill_spacing, 0.8f * min_perimeter_infill_spacing,
+            shell = offset2(shell, - 0.5f * min_perimeter_infill_spacing, 0.8f * min_perimeter_infill_spacing, ClipperLib::jtSquare);
-                CLIPPER_OFFSET_SCALE, ClipperLib::jtSquare);
             if (shell.empty())
                 continue;
 #else
@@ -705,7 +704,7 @@ PrintObject::discover_vertical_shells()
             // get a triangle in $too_narrow; if we grow it below then the shell
             // would have a different shape from the external surface and we'd still
             // have the same angle, so the next shell would be grown even more and so on.
-            Polygons too_narrow = diff(shell, offset2(shell, -margin, margin, CLIPPER_OFFSET_SCALE, ClipperLib::jtMiter, 5.), true);
+            Polygons too_narrow = diff(shell, offset2(shell, -margin, margin, ClipperLib::jtMiter, 5.), true);
             if (! too_narrow.empty()) {
                 // grow the collapsing parts and add the extra area to  the neighbor layer 
                 // as well as to our original surfaces so that we support this 

xs/xsp/Clipper.xsp

@@ -16,58 +16,53 @@ _constant()
     JT_MITER        = jtMiter
     JT_ROUND        = jtRound
     JT_SQUARE       = jtSquare
-    CLIPPER_OFFSET_SCALE = CLIPPER_OFFSET_SCALE
   CODE:
     RETVAL = ix;
   OUTPUT: RETVAL
 
 Polygons
-offset(polygons, delta, scale = CLIPPER_OFFSET_SCALE, joinType = ClipperLib::jtMiter, miterLimit = 3)
+offset(polygons, delta, joinType = ClipperLib::jtMiter, miterLimit = 3)
     Polygons                polygons
     const float             delta
-    double                  scale
     ClipperLib::JoinType    joinType
     double                  miterLimit
     CODE:
-        offset(polygons, &RETVAL, delta, scale, joinType, miterLimit);
+        offset(polygons, &RETVAL, delta, joinType, miterLimit);
     OUTPUT:
         RETVAL
 
 ExPolygons
-offset_ex(polygons, delta, scale = CLIPPER_OFFSET_SCALE, joinType = ClipperLib::jtMiter, miterLimit = 3)
+offset_ex(polygons, delta, joinType = ClipperLib::jtMiter, miterLimit = 3)
     Polygons                polygons
     const float             delta
-    double                  scale
     ClipperLib::JoinType    joinType
     double                  miterLimit
     CODE:
-        offset(polygons, &RETVAL, delta, scale, joinType, miterLimit);
+        offset(polygons, &RETVAL, delta, joinType, miterLimit);
     OUTPUT:
         RETVAL
 
 Polygons
-offset2(polygons, delta1, delta2, scale = CLIPPER_OFFSET_SCALE, joinType = ClipperLib::jtMiter, miterLimit = 3)
+offset2(polygons, delta1, delta2, joinType = ClipperLib::jtMiter, miterLimit = 3)
     Polygons                polygons
     const float             delta1
     const float             delta2
-    double                  scale
     ClipperLib::JoinType    joinType
     double                  miterLimit
     CODE:
-        offset2(polygons, &RETVAL, delta1, delta2, scale, joinType, miterLimit);
+        offset2(polygons, &RETVAL, delta1, delta2, joinType, miterLimit);
     OUTPUT:
         RETVAL
 
 ExPolygons
-offset2_ex(polygons, delta1, delta2, scale = CLIPPER_OFFSET_SCALE, joinType = ClipperLib::jtMiter, miterLimit = 3)
+offset2_ex(polygons, delta1, delta2, joinType = ClipperLib::jtMiter, miterLimit = 3)
     Polygons                polygons
     const float             delta1
     const float             delta2
-    double                  scale
     ClipperLib::JoinType    joinType
     double                  miterLimit
     CODE:
-        offset2(polygons, &RETVAL, delta1, delta2, scale, joinType, miterLimit);
+        offset2(polygons, &RETVAL, delta1, delta2, joinType, miterLimit);
     OUTPUT:
         RETVAL
 

xs/xsp/Polyline.xsp

@@ -80,13 +80,12 @@ Polyline::rotate(angle, center_sv)
         THIS->rotate(angle, center);
 
 Polygons
-Polyline::grow(delta, scale = CLIPPER_OFFSET_SCALE, joinType = ClipperLib::jtSquare, miterLimit = 3)
+Polyline::grow(delta, joinType = ClipperLib::jtSquare, miterLimit = 3)
     const float             delta
-    double                  scale
     ClipperLib::JoinType    joinType
     double                  miterLimit
     CODE:
-        offset(*THIS, &RETVAL, delta, scale, joinType, miterLimit);
+        offset(*THIS, &RETVAL, delta, joinType, miterLimit);
     OUTPUT:
         RETVAL
 

xs/xsp/Surface.xsp

@@ -83,13 +83,12 @@ Surface::polygons()
         RETVAL
 
 Surfaces
-Surface::offset(delta, scale = CLIPPER_OFFSET_SCALE, joinType = ClipperLib::jtMiter, miterLimit = 3)
+Surface::offset(delta, joinType = ClipperLib::jtMiter, miterLimit = 3)
     const float             delta
-    double                  scale
     ClipperLib::JoinType    joinType
     double                  miterLimit
     CODE:
-        offset(*THIS, &RETVAL, delta, scale, joinType, miterLimit);
+        offset(*THIS, &RETVAL, delta, joinType, miterLimit);
     OUTPUT:
         RETVAL