PNS: Detect collisions including newline width

The new line collision search uses BBox() to check for colliding
objects.  BBox in the SHAPE_LINE_CHAIN did not include width as the
chains were assumed to be zero-width.  This is not the case for
PNS::LINE elements.

We mostly don't notice this because DRC checks for SEGMENT collisions
but it becomes obvious/annoying when we cannot place a track for unknown
reasons and the snap-back doesn't take line width into account.

Fixes #3776 | https://gitlab.com/kicad/code/kicad/issues/3776

libs/kimath/include/geometry/shape_line_chain.h

@@ -79,19 +79,21 @@ public:
      * Constructor
      * Initializes an empty line chain.
      */
-    SHAPE_LINE_CHAIN() :
+    SHAPE_LINE_CHAIN() : SHAPE( SH_LINE_CHAIN ), m_closed( false ), m_width( 0 )
-        SHAPE( SH_LINE_CHAIN ), m_closed( false )
     {}
 
     /**
      * Copy Constructor
      */
-    SHAPE_LINE_CHAIN( const SHAPE_LINE_CHAIN& aShape ) :
+    SHAPE_LINE_CHAIN( const SHAPE_LINE_CHAIN& aShape )
-        SHAPE( SH_LINE_CHAIN ), m_points( aShape.m_points ), m_closed( aShape.m_closed )
+            : SHAPE( SH_LINE_CHAIN ),
+              m_points( aShape.m_points ),
+              m_closed( aShape.m_closed ),
+              m_width( aShape.m_width )
     {}
 
     SHAPE_LINE_CHAIN( const std::vector<wxPoint>& aV, bool aClosed = false )
-            : SHAPE( SH_LINE_CHAIN ), m_closed( aClosed )
+            : SHAPE( SH_LINE_CHAIN ), m_closed( aClosed ), m_width( 0 )
     {
         m_points.reserve( aV.size() );
 
@@ -100,14 +102,13 @@ public:
     }
 
     SHAPE_LINE_CHAIN( const std::vector<VECTOR2I>& aV, bool aClosed = false )
-            : SHAPE( SH_LINE_CHAIN ), m_closed( aClosed )
+            : SHAPE( SH_LINE_CHAIN ), m_closed( aClosed ), m_width( 0 )
     {
         m_points = aV;
     }
 
-    SHAPE_LINE_CHAIN( const ClipperLib::Path& aPath ) :
+    SHAPE_LINE_CHAIN( const ClipperLib::Path& aPath )
-        SHAPE( SH_LINE_CHAIN ),
+            : SHAPE( SH_LINE_CHAIN ), m_closed( true ), m_width( 0 )
-        m_closed( true )
     {
         m_points.reserve( aPath.size() );
 
@@ -154,6 +155,24 @@ public:
         return m_closed;
     }
 
+    /**
+     * Sets the width of all segments in the chain
+     * @param aWidth width in internal units
+     */
+    void SetWidth( int aWidth )
+    {
+        m_width = aWidth;
+    }
+
+    /**
+     * Gets the current width of the segments in the chain
+     * @return width in internal units
+     */
+    int Width() const
+    {
+        return m_width;
+    }
+
     /**
      * Function SegmentCount()
      *
@@ -271,8 +290,8 @@ public:
         BOX2I bbox;
         bbox.Compute( m_points );
 
-        if( aClearance != 0 )
+        if( aClearance != 0 || m_width != 0 )
-            bbox.Inflate( aClearance );
+            bbox.Inflate( aClearance + m_width );
 
         return bbox;
     }
@@ -280,6 +299,9 @@ public:
     void GenerateBBoxCache()
     {
         m_bbox.Compute( m_points );
+
+        if( m_width != 0 )
+            m_bbox.Inflate( m_width );
     }
 
     /**
@@ -674,6 +696,12 @@ private:
     /// is the line chain closed?
     bool m_closed;
 
+    /// Width of the segments (for BBox calculations in RTree)
+    /// TODO Adjust usage of SHAPE_LINE_CHAIN to account for where we need a width and where not
+    /// Alternatively, we could split the class into a LINE_CHAIN (no width) and SHAPE_LINE_CHAIN that derives from
+    /// SHAPE as well that does have a width.  Not sure yet on the correct path.
+    int m_width;
+
     /// cached bounding box
     BOX2I m_bbox;
 };

pcbnew/router/pns_line.h

@@ -122,6 +122,7 @@ public:
     void SetShape( const SHAPE_LINE_CHAIN& aLine )
     {
         m_line = aLine;
+        m_line.SetWidth( m_width );
     }
 
     ///> Returns the shape of the line
@@ -170,6 +171,7 @@ public:
     void SetWidth( int aWidth )
     {
         m_width = aWidth;
+        m_line.SetWidth( aWidth );
     }
 
     ///> Returns line width