Prevent creating arcs with slightly offset endpoints

libs/kimath/include/geometry/shape_arc.h

@@ -46,7 +46,8 @@ public:
     {};
 
     /**
-     * SHAPE_ARC ctor.
+     * SHAPE_ARC ctor using center, start, angle.  Center and angle are used to calculate the mid
+     * and end points of the arc, and are not stored
      * @param aArcCenter is the arc center
      * @param aArcStartPoint is the arc start point
      * @param aCenterAngle is the arc angle in degrees
@@ -84,6 +85,17 @@ public:
         return new SHAPE_ARC( *this );
     }
 
+    /**
+     * Constructs this arc from the given start, end and angle.
+     * @param aStart is the arc starting point
+     * @param aEnd is the arc endpoint
+     * @param aAngle is the arc included angle
+     * @param aWidth is the arc line thickness
+     * @return *this
+     */
+    SHAPE_ARC& ConstructFromStartEndAngle( const VECTOR2I& aStart, const VECTOR2I& aEnd,
+                                           double aAngle, double aWidth = 0 );
+
     const VECTOR2I& GetP0() const { return m_start; }
     const VECTOR2I& GetP1() const { return m_end; }
     const VECTOR2I& GetArcMid() const { return m_mid; }

libs/kimath/src/geometry/direction_45.cpp

@@ -66,7 +66,6 @@ const SHAPE_LINE_CHAIN DIRECTION_45::BuildInitialTrace( const VECTOR2I& aP0, con
      * the distance from A to aP1 (diagLength) to calculate the radius of the arc.
      */
 
-    VECTOR2I arcStart, arcCenter;
     int tangentLength;
 
     if( w > h )
@@ -87,6 +86,9 @@ const SHAPE_LINE_CHAIN DIRECTION_45::BuildInitialTrace( const VECTOR2I& aP0, con
     // TODO: if tangentLength zero, we could still place a small arc at the start...
     if( aFillet )
     {
+        VECTOR2I arcStart;
+        VECTOR2D arcCenter;
+
         double diag2 = tangentLength >= 0 ? mp1.SquaredEuclideanNorm() : mp0.SquaredEuclideanNorm();
         double diagLength = std::sqrt( ( 2 * diag2 ) - ( 2 * diag2 * std::cos( 3 * M_PI_4 ) ) );
         int    arcRadius  = KiROUND( diagLength / ( 2.0 * std::cos( 67.5 * M_PI / 180.0 ) ) );
@@ -107,7 +109,6 @@ const SHAPE_LINE_CHAIN DIRECTION_45::BuildInitialTrace( const VECTOR2I& aP0, con
                 arcStart  = aP0 + mp1 + mp0.Resize( mp1.EuclideanNorm() );
                 arcCenter = arcStart + centerDir.Resize( arcRadius );
                 SHAPE_ARC new_arc( arcCenter, aP0, 45 * rotationSign );
-
                 pl.Append( new_arc );
                 pl.Append( aP1 );
             }
@@ -116,14 +117,12 @@ const SHAPE_LINE_CHAIN DIRECTION_45::BuildInitialTrace( const VECTOR2I& aP0, con
                 // Negative tangentLength, diagonal start: arc goes at the end
                 arcStart  = aP0 + mp1.Resize( std::abs( tangentLength ) );
                 arcCenter = aP1 + centerDir.Resize( arcRadius );
-                SHAPE_ARC new_arc( arcCenter, arcStart, 45 * rotationSign );
+
+                SHAPE_ARC new_arc;
+                new_arc.ConstructFromStartEndAngle( arcStart, aP1, 45 * rotationSign );
 
                 pl.Append( aP0 );
                 pl.Append( new_arc );
-
-                // TODO: nicer way of fixing these up
-                if( new_arc.GetP1() != aP1 )
-                    pl.Replace( -1, -1, aP1 );
             }
         }
         else
@@ -136,14 +135,12 @@ const SHAPE_LINE_CHAIN DIRECTION_45::BuildInitialTrace( const VECTOR2I& aP0, con
                 // Positive tangentLength: arc goes at the end
                 arcStart  = aP0 + mp0.Resize( tangentLength );
                 arcCenter = arcStart + centerDir.Resize( arcRadius );
-                SHAPE_ARC new_arc( arcCenter, arcStart, 45 * rotationSign );
+
+                SHAPE_ARC new_arc;
+                new_arc.ConstructFromStartEndAngle( arcStart, aP1, 45 * rotationSign );
 
                 pl.Append( aP0 );
                 pl.Append( new_arc );
-
-                // TODO: nicer way of fixing these up
-                if( new_arc.GetP1() != aP1 )
-                    pl.Replace( -1, -1, aP1 );
             }
             else
             {

libs/kimath/src/geometry/shape_arc.cpp

@@ -32,7 +32,7 @@
 
 SHAPE_ARC::SHAPE_ARC( const VECTOR2I& aArcCenter, const VECTOR2I& aArcStartPoint,
                       double aCenterAngle, int aWidth ) :
-    SHAPE( SH_ARC ), m_width( aWidth )
+        SHAPE( SH_ARC ), m_width( aWidth )
 {
     m_start = aArcStartPoint;
     m_mid = aArcStartPoint;
@@ -170,6 +170,24 @@ SHAPE_ARC::SHAPE_ARC( const SHAPE_ARC& aOther )
 }
 
 
+SHAPE_ARC& SHAPE_ARC::ConstructFromStartEndAngle( const VECTOR2I& aStart, const VECTOR2I& aEnd,
+                                                  double aAngle, double aWidth )
+{
+    m_start = aStart;
+    m_mid   = aStart;
+    m_end   = aEnd;
+    m_width = aWidth;
+
+    VECTOR2I center( GetArcCenter( aStart, aEnd, aAngle ) );
+
+    RotatePoint( m_mid, center, -aAngle * 10.0 / 2.0 );
+
+    update_bbox();
+
+    return *this;
+}
+
+
 bool SHAPE_ARC::Collide( const SEG& aSeg, int aClearance, int* aActual, VECTOR2I* aLocation ) const
 {
     int minDist = aClearance + m_width / 2;