From 3a8744d0541cf3bcfb06d4d37c9dadc66ed5e556 Mon Sep 17 00:00:00 2001
From: Tomasz Wlostowski <tomasz.wlostowski@cern.ch>
Date: Tue, 27 Apr 2021 00:24:37 +0200
Subject: [PATCH] router: introduce concept of a root lines in the OPTIMIZER.

By 'root lines' we mean the oldest traceable ancestor of each track moved by the router
(i.e. after shoving for a while, the root of each shoved line is it's latest non-shoved version).

With this we can teach the OPTIMIZER more tricks, such as the LIMIT_CORNER_COUNT constraint. It ensures
the results of the optimization will not be less cornery than the original line, reducing the feeling
of the optimizer being too intrusive.
---
 pcbnew/router/pns_optimizer.cpp | 33 ++++++++++++++++++++++++++++++++-
 pcbnew/router/pns_optimizer.h   | 29 +++++++++++++++++++++++++++--
 2 files changed, 59 insertions(+), 3 deletions(-)

diff --git a/pcbnew/router/pns_optimizer.cpp b/pcbnew/router/pns_optimizer.cpp
index 70e7e7e84b..e1da771d87 100644
--- a/pcbnew/router/pns_optimizer.cpp
+++ b/pcbnew/router/pns_optimizer.cpp
@@ -272,6 +272,21 @@ bool RESTRICT_VERTEX_RANGE_CONSTRAINT::Check( int aVertex1, int aVertex2, const
     return true;
 }
 
+
+bool CORNER_COUNT_LIMIT_CONSTRAINT::Check( int aVertex1, int aVertex2, const LINE* aOriginLine,
+                                                const SHAPE_LINE_CHAIN& aCurrentPath,
+                                                const SHAPE_LINE_CHAIN& aReplacement )
+{
+    LINE newPath( *aOriginLine, aCurrentPath );
+    newPath.Line().Replace( aVertex1, aVertex2, aReplacement );
+    int cc = newPath.CountCorners( m_angleMask );
+    if( cc >= m_minCorners && cc <= m_maxCorners )
+        return true;
+
+    return false;
+}
+
+
 /**
  * Determine if a point is located within a given polygon
  *
@@ -587,8 +602,16 @@ bool OPTIMIZER::mergeColinear( LINE* aLine )
 }
 
 
-bool OPTIMIZER::Optimize( LINE* aLine, LINE* aResult )
+bool OPTIMIZER::Optimize( LINE* aLine, LINE* aResult, LINE* aRoot )
 {
+    g_dbg = ROUTER::GetInstance()->GetInterface()->GetDebugDecorator();
+
+    if( aRoot )
+    {
+        g_dbg->AddLine( aRoot->CLine(), 3, 100000 );
+    }
+
+
     if( !aResult )
     {
         aResult = aLine;
@@ -602,6 +625,14 @@ bool OPTIMIZER::Optimize( LINE* aLine, LINE* aResult )
     bool hasArcs = aLine->ArcCount();
     bool rv = false;
 
+    if( (m_effortLevel & LIMIT_CORNER_COUNT) && aRoot )
+    {
+        const int angleMask = DIRECTION_45::ANG_OBTUSE;
+        int rootObtuseCorners = aRoot->CountCorners( angleMask );
+        auto c = new CORNER_COUNT_LIMIT_CONSTRAINT( m_world, rootObtuseCorners, aLine->SegmentCount(), angleMask );
+        AddConstraint( c );
+    }
+
     if( m_effortLevel & PRESERVE_VERTEX )
     {
         auto c = new PRESERVE_VERTEX_CONSTRAINT( m_world, m_preservedVertex );
diff --git a/pcbnew/router/pns_optimizer.h b/pcbnew/router/pns_optimizer.h
index f63f021527..401ba9c53f 100644
--- a/pcbnew/router/pns_optimizer.h
+++ b/pcbnew/router/pns_optimizer.h
@@ -104,7 +104,9 @@ public:
         PRESERVE_VERTEX       = 0x20,
         RESTRICT_VERTEX_RANGE = 0x40,
         MERGE_COLINEAR        = 0x80,    ///< Merge co-linear segments
-        RESTRICT_AREA         = 0x100
+        RESTRICT_AREA         = 0x100,
+        LIMIT_CORNER_COUNT    = 0x200  ///< Do not attempt to optimize if the resulting line's
+                                       ///< corner count is outside the predefined range
     };
 
     OPTIMIZER( NODE* aWorld );
@@ -114,7 +116,7 @@ public:
     static bool Optimize( LINE* aLine, int aEffortLevel, NODE* aWorld,
                           const VECTOR2I aV = VECTOR2I(0, 0) );
 
-    bool Optimize( LINE* aLine, LINE* aResult = NULL );
+    bool Optimize( LINE* aLine, LINE* aResult = nullptr, LINE* aRoot = nullptr );
     bool Optimize( DIFF_PAIR* aPair );
 
 
@@ -326,6 +328,29 @@ private:
 };
 
 
+class CORNER_COUNT_LIMIT_CONSTRAINT: public OPT_CONSTRAINT
+{
+public:
+    CORNER_COUNT_LIMIT_CONSTRAINT( NODE* aWorld, int aMinCorners, int aMaxCorners, int aAngleMask ) :
+        OPT_CONSTRAINT( aWorld ),
+        m_minCorners( aMinCorners ),
+        m_maxCorners( aMaxCorners ),
+        m_angleMask( aAngleMask )
+    {
+    };
+
+    virtual bool Check( int aVertex1, int aVertex2, const LINE* aOriginLine,
+                        const SHAPE_LINE_CHAIN& aCurrentPath,
+                        const SHAPE_LINE_CHAIN& aReplacement ) override;
+
+private:
+    int m_minCorners;
+    int m_maxCorners;
+    int m_angleMask;
+};
+
+
+
 };
 
 #endif // __PNS_OPTIMIZER_H