From d6f4f3aca0c5dd6e9194bcbd87beb45b4d8c47d4 Mon Sep 17 00:00:00 2001
From: John Beard <john.j.beard@gmail.com>
Date: Wed, 9 Jan 2019 12:01:00 +0000
Subject: [PATCH] Geom: Account for quadrant points in arc bbox calc

This means arcs that pass though quadrant points (multiple of
0, 90, 180, 270 degrees) include these points in the bbox.
---
 common/geometry/shape_arc.cpp         | 32 +++++++++++++++++++++++++++
 qa/common/geometry/test_shape_arc.cpp |  7 +-----
 2 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/common/geometry/shape_arc.cpp b/common/geometry/shape_arc.cpp
index 2a596b9b9d..136223d58d 100644
--- a/common/geometry/shape_arc.cpp
+++ b/common/geometry/shape_arc.cpp
@@ -22,6 +22,7 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
  */
 
+#include <algorithm>
 #include <vector>
 
 #include <geometry/geometry_utils.h>
@@ -158,6 +159,37 @@ const BOX2I SHAPE_ARC::BBox( int aClearance ) const
     points.push_back( m_p0 );
     points.push_back( GetP1() );
 
+    double start_angle = GetStartAngle();
+    double end_angle = start_angle + GetCentralAngle();
+
+    // we always count quadrants clockwise (increasing angle)
+    if( start_angle > end_angle )
+        std::swap( start_angle, end_angle );
+
+    int quad_angle_start = std::ceil( start_angle / 90.0 );
+    int quad_angle_end = std::floor( end_angle / 90.0 );
+
+    // count through quadrants included in arc
+    for( int quad_angle = quad_angle_start; quad_angle <= quad_angle_end; ++quad_angle )
+    {
+        const int radius = GetRadius();
+        VECTOR2I  quad_pt = m_pc;
+
+        switch( quad_angle % 4 )
+        {
+        case 0: quad_pt += { radius, 0 }; break;
+        case 1:
+        case -3: quad_pt += { 0, radius }; break;
+        case 2:
+        case -2: quad_pt += { -radius, 0 }; break;
+        case 3:
+        case -1: quad_pt += { 0, -radius }; break;
+        default: assert( false );
+        }
+
+        points.push_back( quad_pt );
+    }
+
     bbox.Compute( points );
 
     if( aClearance != 0 )
diff --git a/qa/common/geometry/test_shape_arc.cpp b/qa/common/geometry/test_shape_arc.cpp
index 26b82234a8..9bcd5bd795 100644
--- a/qa/common/geometry/test_shape_arc.cpp
+++ b/qa/common/geometry/test_shape_arc.cpp
@@ -266,10 +266,7 @@ static const std::vector<ARC_CPA_CASE> arc_cases = {
     },
 };
 
-#ifdef HAVE_EXPECTED_FAILURES
-// One of the bbox tests fails
-
-BOOST_AUTO_TEST_CASE( BasicCPAGeom, *boost::unit_test::expected_failures( 6 ) )
+BOOST_AUTO_TEST_CASE( BasicCPAGeom )
 {
     for( const auto& c : arc_cases )
     {
@@ -284,6 +281,4 @@ BOOST_AUTO_TEST_CASE( BasicCPAGeom, *boost::unit_test::expected_failures( 6 ) )
     }
 }
 
-#endif // HAVE_EXPECTED_FAILURES
-
 BOOST_AUTO_TEST_SUITE_END()