libarea: added OffsetWithClipper function

Also added a few extra setting variables.

OffsetWithClipper perform offset operation using
ClipperLib::ClipperOffset.

src/Mod/Path/libarea/Area.cpp

@@ -10,7 +10,11 @@
 
 double CArea::m_accuracy = 0.01;
 double CArea::m_units = 1.0;
+bool CArea::m_clipper_simple = false;
+double CArea::m_clipper_clean_distance = 0.0;
 bool CArea::m_fit_arcs = true;
+int CArea::m_min_arc_points = 4;
+int CArea::m_max_arc_points = 100;
 double CArea::m_single_area_processing_length = 0.0;
 double CArea::m_processing_done = 0.0;
 bool CArea::m_please_abort = false;

src/Mod/Path/libarea/Area.h

@@ -7,6 +7,7 @@
 #define AREA_HEADER
 
 #include "Curve.h"
+#include "clipper.hpp"
 
 enum PocketMode
 {
@@ -42,7 +43,11 @@ public:
 	std::list<CCurve> m_curves;
 	static double m_accuracy;
 	static double m_units; // 1.0 for mm, 25.4 for inches. All points are multiplied by this before going to the engine
+	static bool m_clipper_simple;
+	static double m_clipper_clean_distance;
 	static bool m_fit_arcs;
+    static int m_min_arc_points;
+    static int m_max_arc_points;
 	static double m_processing_done; // 0.0 to 100.0, set inside MakeOnePocketCurve
 	static double m_single_area_processing_length;
 	static double m_after_MakeOffsets_length;
@@ -50,6 +55,7 @@ public:
 	static double m_split_processing_length;
 	static bool m_set_processing_length_in_split;
 	static bool m_please_abort; // the user sets this from another thread, to tell MakeOnePocketCurve to finish with no result.
+    static double m_clipper_scale;
 
 	void append(const CCurve& curve);
 	void Subtract(const CArea& a2);
@@ -58,6 +64,11 @@ public:
 	static CArea UniteCurves(std::list<CCurve> &curves);
 	void Xor(const CArea& a2);
 	void Offset(double inwards_value);
+    void OffsetWithClipper(double offset, 
+                            ClipperLib::JoinType joinType=ClipperLib::jtRound, 
+                            ClipperLib::EndType endType=ClipperLib::etOpenRound,
+                            double miterLimit = 5.0, 
+                            double roundPrecision = 0.0);
 	void Thicken(double value);
 	void FitArcs();
 	unsigned int num_curves(){return static_cast<int>(m_curves.size());}

src/Mod/Path/libarea/AreaClipper.cpp

@@ -12,7 +12,7 @@ using namespace ClipperLib;
 bool CArea::HolesLinked(){ return false; }
 
 //static const double PI = 3.1415926535897932;
-static double Clipper4Factor = 10000.0;
+double CArea::m_clipper_scale = 10000.0;
 
 class DoubleAreaPoint
 {
@@ -20,8 +20,8 @@ public:
 	double X, Y;
 
 	DoubleAreaPoint(double x, double y){X = x; Y = y;}
-	DoubleAreaPoint(const IntPoint& p){X = (double)(p.X) / Clipper4Factor; Y = (double)(p.Y) / Clipper4Factor;}
+	DoubleAreaPoint(const IntPoint& p){X = (double)(p.X) / CArea::m_clipper_scale; Y = (double)(p.Y) / CArea::m_clipper_scale;}
-	IntPoint int_point(){return IntPoint((long64)(X * Clipper4Factor), (long64)(Y * Clipper4Factor));}
+	IntPoint int_point(){return IntPoint((long64)(X * CArea::m_clipper_scale), (long64)(Y * CArea::m_clipper_scale));}
 };
 
 static std::list<DoubleAreaPoint> pts_for_AddVertex;
@@ -81,10 +81,10 @@ static void AddVertex(const CVertex& vertex, const CVertex* prev_vertex)
 		else
 			Segments=(int)ceil(-phit/dphi);
 
-		if (Segments < 1)
+        if (Segments < CArea::m_min_arc_points)
-			Segments=1;
+            Segments = CArea::m_min_arc_points;
-		if (Segments > 100)
+        if (Segments > CArea::m_max_arc_points)
-			Segments=100;
+            Segments=CArea::m_max_arc_points;
 
 		dphi=phit/(Segments);
 
@@ -139,6 +139,7 @@ static void MakeLoop(const DoubleAreaPoint &pt0, const DoubleAreaPoint &pt1, con
 static void OffsetWithLoops(const TPolyPolygon &pp, TPolyPolygon &pp_new, double inwards_value)
 {
 	Clipper c;
+    c.StrictlySimple(CArea::m_clipper_simple);
 
 	bool inwards = (inwards_value > 0);
 	bool reverse = false;
@@ -251,6 +252,7 @@ static void MakeObround(const Point &pt0, const CVertex &vt1, double radius)
 static void OffsetSpansWithObrounds(const CArea& area, TPolyPolygon &pp_new, double radius)
 {
 	Clipper c;
+    c.StrictlySimple(CArea::m_clipper_simple);
 
 
 	for(std::list<CCurve>::const_iterator It = area.m_curves.begin(); It != area.m_curves.end(); It++)
@@ -355,8 +357,11 @@ static void MakePoly(const CCurve& curve, TPolygon &p)
 	}
 }
 
-static void SetFromResult( CCurve& curve, const TPolygon& p, bool reverse = true )
+static void SetFromResult( CCurve& curve, TPolygon& p, bool reverse = true )
 {
+    if(CArea::m_clipper_clean_distance >= Point::tolerance)
+        CleanPolygon(p,CArea::m_clipper_clean_distance);
+
 	for(unsigned int j = 0; j < p.size(); j++)
 	{
 		const IntPoint &pt = p[j];
@@ -372,14 +377,14 @@ static void SetFromResult( CCurve& curve, const TPolygon& p, bool reverse = true
 	if(CArea::m_fit_arcs)curve.FitArcs();
 }
 
-static void SetFromResult( CArea& area, const TPolyPolygon& pp, bool reverse = true )
+static void SetFromResult( CArea& area, TPolyPolygon& pp, bool reverse = true )
 {
 	// delete existing geometry
 	area.m_curves.clear();
 
 	for(unsigned int i = 0; i < pp.size(); i++)
 	{
-		const TPolygon& p = pp[i];
+		TPolygon& p = pp[i];
 
 		area.m_curves.push_back(CCurve());
 		CCurve &curve = area.m_curves.back();
@@ -390,6 +395,7 @@ static void SetFromResult( CArea& area, const TPolyPolygon& pp, bool reverse = t
 void CArea::Subtract(const CArea& a2)
 {
 	Clipper c;
+    c.StrictlySimple(CArea::m_clipper_simple);
 	TPolyPolygon pp1, pp2;
 	MakePolyPoly(*this, pp1);
 	MakePolyPoly(a2, pp2);
@@ -403,6 +409,7 @@ void CArea::Subtract(const CArea& a2)
 void CArea::Intersect(const CArea& a2)
 {
 	Clipper c;
+    c.StrictlySimple(CArea::m_clipper_simple);
 	TPolyPolygon pp1, pp2;
 	MakePolyPoly(*this, pp1);
 	MakePolyPoly(a2, pp2);
@@ -416,6 +423,7 @@ void CArea::Intersect(const CArea& a2)
 void CArea::Union(const CArea& a2)
 {
 	Clipper c;
+    c.StrictlySimple(CArea::m_clipper_simple);
 	TPolyPolygon pp1, pp2;
 	MakePolyPoly(*this, pp1);
 	MakePolyPoly(a2, pp2);
@@ -430,6 +438,7 @@ void CArea::Union(const CArea& a2)
 CArea CArea::UniteCurves(std::list<CCurve> &curves)
 {
 	Clipper c;
+    c.StrictlySimple(CArea::m_clipper_simple);
 
 	TPolyPolygon pp;
 
@@ -452,6 +461,7 @@ CArea CArea::UniteCurves(std::list<CCurve> &curves)
 void CArea::Xor(const CArea& a2)
 {
 	Clipper c;
+    c.StrictlySimple(CArea::m_clipper_simple);
 	TPolyPolygon pp1, pp2;
 	MakePolyPoly(*this, pp1);
 	MakePolyPoly(a2, pp2);
@@ -471,6 +481,37 @@ void CArea::Offset(double inwards_value)
 	this->Reorder();
 }
 
+void CArea::OffsetWithClipper(double offset, 
+                              JoinType joinType/* =jtRound */,
+                              EndType endType/* =etOpenRound */,
+                              double miterLimit/*  = 5.0 */,
+                              double roundPrecision/*  = 0.0 */)
+{
+    offset *= m_units*m_clipper_scale;
+    if(roundPrecision == 0.0) {
+        // Clipper roundPrecision definition: https://goo.gl/4odfQh
+		double dphi=acos(1.0-m_accuracy*m_clipper_scale/fabs(offset));
+        int Segments=(int)ceil(PI/dphi);
+        if (Segments < 2*CArea::m_min_arc_points)
+            Segments = 2*CArea::m_min_arc_points;
+        if (Segments > CArea::m_max_arc_points)
+            Segments=CArea::m_max_arc_points;
+        dphi = PI/Segments;
+        roundPrecision = (1.0-cos(dphi))*fabs(offset);
+    }else
+        roundPrecision *= m_clipper_scale;
+
+    ClipperOffset clipper(miterLimit,roundPrecision);
+	TPolyPolygon pp, pp2;
+	MakePolyPoly(*this, pp, false);
+    int i=0;
+    for(const CCurve &c : m_curves) 
+        clipper.AddPath(pp[i++],joinType,c.IsClosed()?etClosedPolygon:endType);
+    clipper.Execute(pp2,(long64)(offset));
+	SetFromResult(*this, pp2, false);
+    this->Reorder();
+}
+
 void CArea::Thicken(double value)
 {
 	TPolyPolygon pp;