From 4bf35cbed83cd5a0558d258952cd1577fb58eee3 Mon Sep 17 00:00:00 2001
From: Seth Hillbrand <seth@kipro-pcb.com>
Date: Fri, 29 Mar 2024 12:53:15 -0700
Subject: [PATCH] Remove duplicated clearanceEpsilon

We already get clearance epsilon in the clearance resolver.  Don't
subtract it twice or we end up getting DRC errors

Fixes https://gitlab.com/kicad/code/kicad/-/issues/16879

(cherry picked from commit 10c1072479b668d3b453d4bda288569ae94ea467)
---
 pcbnew/router/pns_item.cpp | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/pcbnew/router/pns_item.cpp b/pcbnew/router/pns_item.cpp
index 042fe0e497..486739fbd8 100644
--- a/pcbnew/router/pns_item.cpp
+++ b/pcbnew/router/pns_item.cpp
@@ -103,7 +103,6 @@ bool ITEM::collideSimple( const ITEM* aHead, const NODE* aNode,
     const SHAPE* shapeH = aHead->Shape();
     const HOLE*  holeH = aHead->Hole();
     int          lineWidthH = 0;
-    int          clearanceEpsilon = aNode->GetRuleResolver()->ClearanceEpsilon();
     bool         collisionsFound = false;
 
     if( this == aHead )  // we cannot be self-colliding
@@ -212,8 +211,10 @@ bool ITEM::collideSimple( const ITEM* aHead, const NODE* aNode,
             int      actual;
             VECTOR2I pos;
 
-            if( shapeH->Collide( shapeI, clearance + lineWidthH + lineWidthI - clearanceEpsilon,
-                                 &actual, &pos ) )
+            // The extra "1" here is to account for the fact that the hulls are built to exactly
+            // the clearance distance, so we need to allow for no collision when exactly at the
+            // clearance distance.
+            if( shapeH->Collide( shapeI, clearance + lineWidthH + lineWidthI - 1, &actual, &pos ) )
             {
                 if( checkCastellation && aNode->QueryEdgeExclusions( pos ) )
                     return false;
@@ -241,7 +242,10 @@ bool ITEM::collideSimple( const ITEM* aHead, const NODE* aNode,
         else
         {
             // Fast method
-            if( shapeH->Collide( shapeI, clearance + lineWidthH + lineWidthI - clearanceEpsilon ) )
+            // The extra "1" here is to account for the fact that the hulls are built to exactly
+            // the clearance distance, so we need to allow for no collision when exactly at the
+            // clearance distance.
+            if( shapeH->Collide( shapeI, clearance + lineWidthH + lineWidthI - 1 ) )
             {
                 if( aCtx )
                 {