From aa0787f2b49aa7641fdda939ff4be87d942d3a3f Mon Sep 17 00:00:00 2001
From: jean-pierre charras <jp.charras@wanadoo.fr>
Date: Mon, 28 Feb 2022 15:32:10 +0100
Subject: [PATCH] Gerber plotter: fix broken plot of SHAPE_LINE_CHAIN with
 arcs. Also simplify SHAPE_T::POLY plot. Fixes #10989
 https://gitlab.com/kicad/code/kicad/issues/10989

---
 common/plotters/GERBER_plotter.cpp | 27 ++++++++++++++++++++++-----
 pcbnew/plot_brditems_plotter.cpp   | 19 +++++++++++--------
 2 files changed, 33 insertions(+), 13 deletions(-)

diff --git a/common/plotters/GERBER_plotter.cpp b/common/plotters/GERBER_plotter.cpp
index b64cd004b2..63f53f82cb 100644
--- a/common/plotters/GERBER_plotter.cpp
+++ b/common/plotters/GERBER_plotter.cpp
@@ -843,8 +843,16 @@ void GERBER_PLOTTER::plotArc( const SHAPE_ARC& aArc, bool aPlotInRegion )
     VECTOR2I  start( aArc.GetP0() );
     VECTOR2I  end( aArc.GetP1() );
     VECTOR2I  center( aArc.GetCenter() );
-    EDA_ANGLE start_angle = aArc.GetStartAngle();
-    EDA_ANGLE end_angle = aArc.GetEndAngle();
+    EDA_ANGLE startAngle = aArc.GetStartAngle();
+    EDA_ANGLE endAngle = aArc.GetEndAngle();
+
+    if( startAngle > endAngle )
+    {
+        if( endAngle < ANGLE_0 )
+            endAngle.Normalize();
+        else
+            startAngle = startAngle.Normalize() - ANGLE_360;
+    }
 
     if( !aPlotInRegion )
         MoveTo( start);
@@ -856,7 +864,7 @@ void GERBER_PLOTTER::plotArc( const SHAPE_ARC& aArc, bool aPlotInRegion )
 
     fprintf( m_outputFile, "G75*\n" );        // Multiquadrant (360 degrees) mode
 
-    if( start_angle < end_angle )
+    if( startAngle > endAngle )
         fprintf( m_outputFile, "G03*\n" );    // Active circular interpolation, CCW
     else
         fprintf( m_outputFile, "G02*\n" );    // Active circular interpolation, CW
@@ -1011,6 +1019,10 @@ void GERBER_PLOTTER::PlotPoly( const SHAPE_LINE_CHAIN& aPoly, FILL_T aFill, int
                 const SHAPE_ARC& arc = aPoly.Arc( arcindex );
 
                 plotArc( arc, ii > 0 );
+
+                // skip points on arcs, since we plot the arc itself
+                while( ii+1 < aPoly.PointCount() && arcindex == aPoly.ArcIndex( ii+1 ) )
+                    ii++;
             }
         }
 
@@ -1041,12 +1053,17 @@ void GERBER_PLOTTER::PlotPoly( const SHAPE_LINE_CHAIN& aPoly, FILL_T aFill, int
                 const SHAPE_ARC& arc = aPoly.Arc( arcindex );
 
                 plotArc( arc, ii > 0 );
-            }
+
+                // skip points on arcs, since we plot the arc itself
+                while( ii+1 < aPoly.PointCount() && arcindex == aPoly.ArcIndex( ii+1 ) )
+                    ii++;
+             }
         }
 
         // Ensure the thick outline is closed for filled polygons
         // (if not filled, could be only a polyline)
-        if( aFill != FILL_T::NO_FILL && ( aPoly.CPoint( 0 ) != aPoly.CPoint( -1 ) ) )
+        if( ( aPoly.CPoint( 0 ) != aPoly.CPoint( -1 ) )
+            && ( aPoly.IsClosed() || aFill != FILL_T::NO_FILL ) )
             LineTo( VECTOR2I( aPoly.CPoint( 0 ) ) );
 
         PenFinish();
diff --git a/pcbnew/plot_brditems_plotter.cpp b/pcbnew/plot_brditems_plotter.cpp
index db612b3004..1d8e49eec6 100644
--- a/pcbnew/plot_brditems_plotter.cpp
+++ b/pcbnew/plot_brditems_plotter.cpp
@@ -707,7 +707,7 @@ void BRDITEMS_PLOTTER::PlotFootprintShape( const FP_SHAPE* aShape )
                     }
                 }
 
-                if( sketch || thickness > 0 )
+                if( sketch )
                 {
                     for( size_t i = 1; i < cornerList.size(); i++ )
                     {
@@ -719,8 +719,7 @@ void BRDITEMS_PLOTTER::PlotFootprintShape( const FP_SHAPE* aShape )
                                              GetPlotMode(), &gbr_metadata );
 
                 }
-
-                if( !sketch && aShape->IsFilled() )
+                else
                 {
                     // This must be simplified and fractured to prevent overlapping polygons
                     // from generating invalid Gerber files
@@ -966,7 +965,7 @@ void BRDITEMS_PLOTTER::PlotPcbShape( const PCB_SHAPE* aShape )
         case SHAPE_T::POLY:
             if( aShape->IsPolyShapeValid() )
             {
-                if( sketch || thickness > 0 )
+                if( sketch )
                 {
                     for( auto it = aShape->GetPolyShape().CIterateSegments( 0 ); it; it++ )
                     {
@@ -975,8 +974,7 @@ void BRDITEMS_PLOTTER::PlotPcbShape( const PCB_SHAPE* aShape )
                                                  &gbr_metadata );
                     }
                 }
-
-                if( !sketch && aShape->IsFilled() )
+                else
                 {
                     m_plotter->SetCurrentLineWidth( thickness, &gbr_metadata );
 
@@ -985,13 +983,18 @@ void BRDITEMS_PLOTTER::PlotPcbShape( const PCB_SHAPE* aShape )
                     // ( for the future or to show a non expected shape )
                     // This must be simplified and fractured to prevent overlapping polygons
                     // from generating invalid Gerber files
-                    auto tmpPoly = SHAPE_POLY_SET( aShape->GetPolyShape() );
+                    SHAPE_POLY_SET tmpPoly = SHAPE_POLY_SET( aShape->GetPolyShape() );
                     tmpPoly.Fracture( SHAPE_POLY_SET::PM_FAST );
+                    FILL_T fill = aShape->IsFilled() ? FILL_T::FILLED_SHAPE : FILL_T::NO_FILL;
 
                     for( int jj = 0; jj < tmpPoly.OutlineCount(); ++jj )
                     {
                         SHAPE_LINE_CHAIN& poly = tmpPoly.Outline( jj );
-                        m_plotter->PlotPoly( poly, FILL_T::FILLED_SHAPE, thickness, &gbr_metadata );
+
+                        // Ensure the polygon is closed:
+                        poly.SetClosed( true );
+
+                        m_plotter->PlotPoly( poly, fill, thickness, &gbr_metadata );
                     }
                 }
             }