Added a new join type (JoinType::Bevel) for offsetting //AngusJohnson…

…#615

CPP/Clipper2Lib/include/clipper2/clipper.offset.h

@@ -1,6 +1,6 @@
 /*******************************************************************************
 * Author    :  Angus Johnson                                                   *
-* Date      :  15 May 2023                                                     *
+* Date      :  24 September 2023                                               *
 * Website   :  http://www.angusj.com                                           *
 * Copyright :  Angus Johnson 2010-2023                                         *
 * Purpose   :  Path Offset (Inflate/Shrink)                                    *
@@ -15,7 +15,9 @@
 
 namespace Clipper2Lib {
 
-enum class JoinType { Square, Round, Miter };
+enum class JoinType { Square, Bevel, Round, Miter };
+//Square : Joins are 'squared' at exactly the offset distance (more complex code)
+//Bevel  : Similar to Square, but the offset distance varies with angle (simple code & faster)
 
 enum class EndType {Polygon, Joined, Butt, Square, Round};
 //Butt   : offsets both sides of a path, with square blunt ends
@@ -51,7 +53,7 @@ class ClipperOffset {
 	PathD norms;
 	Paths64 solution;
 	std::vector<Group> groups_;
-	JoinType join_type_ = JoinType::Square;
+	JoinType join_type_ = JoinType::Bevel;
 	EndType end_type_ = EndType::Polygon;
 
 	double miter_limit_ = 0.0;
@@ -64,6 +66,7 @@ class ClipperOffset {
 #endif
 	DeltaCallback64 deltaCallback64_ = nullptr;
 
+	void DoBevel(Group& group, const Path64& path, size_t j, size_t k);
 	void DoSquare(Group& group, const Path64& path, size_t j, size_t k);
 	void DoMiter(Group& group, const Path64& path, size_t j, size_t k, double cos_a);
 	void DoRound(Group& group, const Path64& path, size_t j, size_t k, double angle);

CPP/Clipper2Lib/src/clipper.offset.cpp

@@ -1,6 +1,6 @@
 /*******************************************************************************
 * Author    :  Angus Johnson                                                   *
-* Date      :  19 September 2023                                               *
+* Date      :  24 September 2023                                               *
 * Website   :  http://www.angusj.com                                           *
 * Copyright :  Angus Johnson 2010-2023                                         *
 * Purpose   :  Path Offset (Inflate/Shrink)                                    *
@@ -200,6 +200,24 @@ PointD IntersectPoint(const PointD& pt1a, const PointD& pt1b,
 	}
 }
 
+void ClipperOffset::DoBevel(Group& group, const Path64& path, size_t j, size_t k)
+{
+	PointD pt1, pt2;
+	if (j == k)
+	{
+		double abs_delta = std::abs(group_delta_);
+		pt1 = PointD(path[j].x - abs_delta * norms[j].x, path[j].y - abs_delta * norms[j].y);
+		pt2 = PointD(path[j].x + abs_delta * norms[j].x, path[j].y + abs_delta * norms[j].y);
+	} 
+	else
+	{
+		pt1 = PointD(path[j].x + group_delta_ * norms[k].x, path[j].y + group_delta_ * norms[k].y);
+		pt2 = PointD(path[j].x + group_delta_ * norms[j].x, path[j].y + group_delta_ * norms[j].y);
+	}
+	group.path.push_back(Point64(pt1));
+	group.path.push_back(Point64(pt2));
+}
+
 void ClipperOffset::DoSquare(Group& group, const Path64& path, size_t j, size_t k)
 {
 	PointD vec;
@@ -342,10 +360,13 @@ void ClipperOffset::OffsetPoint(Group& group, Path64& path, size_t j, size_t k)
 		if (cos_a > temp_lim_ - 1) DoMiter(group, path, j, k, cos_a);
 		else DoSquare(group, path, j, k);
 	}
-	else if (cos_a > 0.99 || join_type_ == JoinType::Square) // 0.99 ~= 8.1 deg.
-		DoSquare(group, path, j, k);
-	else
+	else if (cos_a > 0.99 || join_type_ == JoinType::Bevel) 
+		// ie > 2.5 deg (see above) but less than ~8 deg ( acos(0.99) )
+		DoBevel(group, path, j, k);
+	else if (join_type_ == JoinType::Round)
 		DoRound(group, path, j, k, std::atan2(sin_a, cos_a));
+	else
+		DoSquare(group, path, j, k);
 }
 
 void ClipperOffset::OffsetPolygon(Group& group, Path64& path)
@@ -394,17 +415,7 @@ void ClipperOffset::OffsetOpenPath(Group& group, Path64& path)
 		switch (end_type_)
 		{
 		case EndType::Butt:
-#ifdef USINGZ
-			group.path.push_back(Point64(
-				path[0].x - norms[0].x * group_delta_,
-				path[0].y - norms[0].y * group_delta_,
-				path[0].z));
-#else
-			group.path.push_back(Point64(
-				path[0].x - norms[0].x * group_delta_,
-				path[0].y - norms[0].y * group_delta_));
-#endif
-			group.path.push_back(GetPerpendic(path[0], norms[0], group_delta_));
+			DoBevel(group, path, 0, 0);
 			break;
 		case EndType::Round:
 			DoRound(group, path, 0, 0, PI);
@@ -436,17 +447,7 @@ void ClipperOffset::OffsetOpenPath(Group& group, Path64& path)
 		switch (end_type_)
 		{
 		case EndType::Butt:
-#ifdef USINGZ
-			group.path.push_back(Point64(
-				path[highI].x - norms[highI].x * group_delta_,
-				path[highI].y - norms[highI].y * group_delta_,
-				path[highI].z));
-#else
-			group.path.push_back(Point64(
-				path[highI].x - norms[highI].x * group_delta_,
-				path[highI].y - norms[highI].y * group_delta_));
-#endif
-			group.path.push_back(GetPerpendic(path[highI], norms[highI], group_delta_));
+			DoBevel(group, path, highI, highI);
 			break;
 		case EndType::Round:
 			DoRound(group, path, highI, highI, PI);

CPP/Examples/Inflate/Inflate.cpp

@@ -13,10 +13,10 @@ void System(const std::string& filename);
 
 int main(int argc, char* argv[])
 {
-  //DoSimpleShapes();
+  DoSimpleShapes();
   DoRabbit();
 
-  std::getchar();
+  //std::getchar();
 }
 
 void DoSimpleShapes() 
@@ -26,23 +26,29 @@ void DoSimpleShapes()
 
   FillRule fr2 = FillRule::EvenOdd;
   SvgWriter svg2;
-  op1.push_back(MakePath({ 80,60, 20,20, 180,20, 180,80, 20,180, 180,180 }));
-  op2 = InflatePaths(op1, 20, JoinType::Square, EndType::Butt);
+  op1.push_back(MakePath({ 80,60, 20,20, 180,20, 180,70, 25,150, 20,180, 180,180 }));
+  op2 = InflatePaths(op1, 20, JoinType::Miter, EndType::Square, 3);
   SvgAddOpenSubject(svg2, op1, fr2, false);
   SvgAddSolution(svg2, Paths64ToPathsD(op2), fr2, false);
-  SvgAddCaption(svg2, "Square Joins; Butt Ends", 20, 220);
+  SvgAddCaption(svg2, "Miter Joins; Square Ends", 20, 210);
 
-  op1 = TranslatePaths(op1, 250, 0);
-  op2 = InflatePaths(op1, 20, JoinType::Miter, EndType::Square, 3);
+  op1 = TranslatePaths<int64_t>(op1, 210, 0);
+  op2 = InflatePaths(op1, 20, JoinType::Square, EndType::Square);
+  SvgAddOpenSubject(svg2, op1, fr2, false);
+  SvgAddSolution(svg2, Paths64ToPathsD(op2), fr2, false);
+  SvgAddCaption(svg2, "Square Joins; Square Ends", 230, 210);
+
+  op1 = TranslatePaths<int64_t>(op1, 210, 0);
+  op2 = InflatePaths(op1, 20, JoinType::Bevel, EndType::Butt, 3);
   SvgAddOpenSubject(svg2, op1, fr2, false);
   SvgAddSolution(svg2, Paths64ToPathsD(op2), fr2, false);
-  SvgAddCaption(svg2, "Miter Joins; Square Ends", 300, 220);
+  SvgAddCaption(svg2, "Bevel Joins; Butt Ends", 440, 210);
 
-  op1 = TranslatePaths(op1, 250, 0);
+  op1 = TranslatePaths<int64_t>(op1, 210, 0);
   op2 = InflatePaths(op1, 20, JoinType::Round, EndType::Round);
   SvgAddOpenSubject(svg2, op1, fr2, false);
   SvgAddSolution(svg2, Paths64ToPathsD(op2), fr2, false);
-  SvgAddCaption(svg2, "Round Joins; Round Ends", 580, 220);
+  SvgAddCaption(svg2, "Round Joins; Round Ends", 650, 210);
 
   SvgSaveToFile(svg2, "open_paths.svg", 800, 600, 20);
   System("open_paths.svg");
@@ -68,7 +74,7 @@ void DoSimpleShapes()
   //different join types within the same offset operation
   ClipperOffset co;
   co.AddPaths(p, JoinType::Miter, EndType::Joined);
-  p = TranslatePaths(p, 120, 100);
+  p = TranslatePaths<int64_t>(p, 120, 100);
   pp.insert(pp.end(), p.begin(), p.end());
   co.AddPaths(p, JoinType::Round, EndType::Joined);
   co.Execute(20, p);

CPP/Utils/clipper.svg.cpp

@@ -260,7 +260,7 @@ namespace Clipper2Lib {
       file << "  <g font-family=\"" << ti->font_name << "\" font-size=\"" <<
         ti->font_size << "\" fill=\"" << ColorToHtml(ti->font_color) <<
         "\" fill-opacity=\"" << GetAlphaAsFrac(ti->font_color) << "\">\n";
-      file << "    <text x=\"" << (ti->x + margin) << "\" y=\"" << (ti->y+margin) << "\">" <<
+      file << "    <text x=\"" << (ti->x * scale + offsetX) << "\" y=\"" << (ti->y * scale + offsetY) << "\">" <<
         ti->text << "</text>\n  </g>\n\n";
     }
 

CSharp/Clipper2Lib.Examples/InflateDemo/Main.cs

@@ -1,8 +1,8 @@
 /*******************************************************************************
 * Author    :  Angus Johnson                                                   *
-* Date      :  19 July 2023                                                    *
+* Date      :  24 September 2023                                               *
 * Website   :  http://www.angusj.com                                           *
-* Copyright :  Angus Johnson 2010-2022                                         *
+* Copyright :  Angus Johnson 2010-2023                                         *
 * License   :  http://www.boost.org/LICENSE_1_0.txt                            *
 *******************************************************************************/
 
@@ -32,28 +32,39 @@ public static void DoSimpleShapes()
 
       for (int i = 0; i < 5; ++i)
       {
-        //nb: the following '10' parameter greatly increases miter limit
+        //nb: the last parameter here (10) greatly increases miter limit
         p = Clipper.InflatePaths(p, 5, JoinType.Miter, EndType.Polygon, 10);
         pp.AddRange(p);
       }
 
       //rectangle offset - both squared and rounded
       p.Clear();
-      p.Add(Clipper.MakePath(new int[] { 100, 0, 340, 0, 340, 200, 100, 200 }));
-      pp.AddRange(p);
+      ClipperOffset co = new();
+
       //nb: using the ClipperOffest class directly here to control 
       //different join types within the same offset operation
-      ClipperOffset co = new();
+      p.Add(Clipper.MakePath(new int[] { 100, 0, 340, 0, 340, 200, 100, 200 }));
+      pp.AddRange(p);
+      co.AddPaths(p, JoinType.Bevel, EndType.Joined);
+
+      p = Clipper.TranslatePaths(p, 60, 50);
+      pp.AddRange(p);
       co.AddPaths(p, JoinType.Square, EndType.Joined);
-      p = Clipper.TranslatePaths(p, 120, 100);
+
+      p = Clipper.TranslatePaths(p, 60, 50);
       pp.AddRange(p);
       co.AddPaths(p, JoinType.Round, EndType.Joined);
+
+
       co.Execute(20, p);
       pp.AddRange(p);
 
       string filename = "../../../inflate.svg";
       SvgWriter svg = new();
       SvgUtils.AddSolution(svg, pp, false);
+      SvgUtils.AddCaption(svg, "Beveled join", 100, -27);
+      SvgUtils.AddCaption(svg, "Squared join", 160, 23);
+      SvgUtils.AddCaption(svg, "Rounded join", 220, 73);
       SvgUtils.SaveToFile(svg, filename, FillRule.EvenOdd, 800, 600, 20);
       ClipperFileIO.OpenFileWithDefaultApp(filename);
     }
@@ -69,7 +80,7 @@ public static void DoRabbit()
         pd = Clipper.InflatePaths(pd, -2.5, JoinType.Round, EndType.Polygon);
         // SimplifyPaths - is not essential but it not only 
         // speeds up the loop but it also tidies the result
-        pd = Clipper.SimplifyPaths(pd, 0.2);
+        pd = Clipper.SimplifyPaths(pd, 0.25);
         solution.AddRange(pd);
       }
 

CSharp/Clipper2Lib/Clipper.Offset.cs

@@ -1,6 +1,6 @@
 /*******************************************************************************
 * Author    :  Angus Johnson                                                   *
-* Date      :  19 September 2023                                               *
+* Date      :  24 September 2023                                               *
 * Website   :  http://www.angusj.com                                           *
 * Copyright :  Angus Johnson 2010-2023                                         *
 * Purpose   :  Path Offset (Inflate/Shrink)                                    *
@@ -15,9 +15,10 @@ namespace Clipper2Lib
 {
   public enum JoinType
   {
+    Miter,
     Square,
-    Round,
-    Miter
+    Bevel,
+    Round
   };
 
   public enum EndType
@@ -323,6 +324,25 @@ private PointD GetPerpendicD(Point64 pt, PointD norm)
 #endif
     }
 
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private void DoBevel(Group group, Path64 path, int j, int k)
+    {
+      Point64 pt1, pt2;
+      if (j == k)
+      {
+        double absDelta = Math.Abs(_groupDelta);
+        pt1 = new Point64(path[j].X - absDelta * _normals[j].x, path[j].Y - absDelta * _normals[j].y);
+        pt2 = new Point64(path[j].X + absDelta * _normals[j].x, path[j].Y + absDelta * _normals[j].y);
+      }
+      else
+      {
+        pt1 = new Point64(path[j].X + _groupDelta * _normals[k].x, path[j].Y + _groupDelta * _normals[k].y);
+        pt2 = new Point64(path[j].X + _groupDelta * _normals[j].x, path[j].Y + _groupDelta * _normals[j].y);
+      }
+      group.outPath.Add(pt1);
+      group.outPath.Add(pt2);
+    }
+
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     private void DoSquare(Group group, Path64 path, int j, int k)
     {
@@ -483,12 +503,14 @@ private void OffsetPoint(Group group, Path64 path, int j, ref int k)
         if (cosA > _mitLimSqr - 1) DoMiter(group, path, j, k, cosA);
         else DoSquare(group, path, j, k);
       }
-      else if (cosA > 0.99 || _joinType == JoinType.Square)
+      else if (cosA > 0.99 || _joinType == JoinType.Bevel)
         //angle less than 8 degrees or a squared join
-        DoSquare(group, path, j, k);
-      else
+        DoBevel(group, path, j, k);
+      else if (_joinType == JoinType.Round)
         DoRound(group, path, j, k, Math.Atan2(sinA, cosA));
-
+      else
+        DoSquare(group, path, j, k);
+
       k = j;
     }
 
@@ -537,17 +559,7 @@ private void OffsetOpenPath(Group group, Path64 path)
         switch (_endType)
         {
           case EndType.Butt:
-#if USINGZ
-            group.outPath.Add(new Point64(
-                path[0].X - _normals[0].x * _groupDelta,
-                path[0].Y - _normals[0].y * _groupDelta,
-                path[0].Z));
-#else
-            group.outPath.Add(new Point64(
-                path[0].X - _normals[0].x * _groupDelta,
-                path[0].Y - _normals[0].y * _groupDelta));
-#endif
-            group.outPath.Add(GetPerpendic(path[0], _normals[0]));
+            DoBevel(group, path, 0, 0);
             break;
           case EndType.Round:
             DoRound(group, path, 0, 0, Math.PI);
@@ -575,17 +587,7 @@ private void OffsetOpenPath(Group group, Path64 path)
         switch (_endType)
         {
           case EndType.Butt:
-#if USINGZ
-            group.outPath.Add(new Point64(
-                path[highI].X - _normals[highI].x * _groupDelta,
-                path[highI].Y - _normals[highI].y * _groupDelta,
-                path[highI].Z));
-#else
-            group.outPath.Add(new Point64(
-                path[highI].X - _normals[highI].x * _groupDelta,
-                path[highI].Y - _normals[highI].y * _groupDelta));
-#endif
-            group.outPath.Add(GetPerpendic(path[highI], _normals[highI]));
+            DoBevel(group, path, highI, highI);
             break;
           case EndType.Round:
             DoRound(group, path, highI, highI, Math.PI);

CSharp/Utils/SVG/Clipper.SVG.cs

@@ -305,7 +305,7 @@ public bool SaveToFile(string filename, int maxWidth = 0, int maxHeight = 0, int
       {
         writer.Write("<g font-family=\"Verdana\" font-style=\"normal\" " +
                      "font-weight=\"normal\" font-size=\"{0}\" fill=\"{1}\">\n", captionInfo.fontSize, ColorToHtml(captionInfo.fontColor));
-        writer.Write("<text x=\"{0}\" y=\"{1}\">{2}</text>\n</g>\n", captionInfo.posX + margin, captionInfo.posY + margin, captionInfo.text);
+        writer.Write("<text x=\"{0}\" y=\"{1}\">{2}</text>\n</g>\n", captionInfo.posX * scale + offsetX, captionInfo.posY * scale + offsetX, captionInfo.text);
       }
 
       writer.Write("</svg>\n");