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.

1 files changed, 17 insertions, 24 deletions

diff --git a/xs/src/libslic3r/ClipperUtils.hpp b/xs/src/libslic3r/ClipperUtils.hpp
index 188867fe5..783453807 100644
--- a/xs/src/libslic3r/ClipperUtils.hpp
+++ b/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>