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Fix errors in arc polygonization and test case. 

1) Tests can't expect accuracies around 1 to work.  PCBNew defaults
to 5000.
2) Tests shouldn't artifically expand tolerance just to match the
results.
3) Tests should guarantee that end point is on arc, not just close
to it.
4) Standard polygonization of a circle is inside so splitting the
error needs to increase radius, not decrease.
5) Special-case first and last points so that they're exact.
This commit is contained in:
Jeff Young 2020-10-23 22:37:34 +01:00
parent c5a86126d2
commit 1cb7fbaab1
2 changed files with 39 additions and 33 deletions
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17
libs/kimath/src/geometry/shape_arc.cpp
View File

@ -376,16 +376,19 @@ const SHAPE_LINE_CHAIN SHAPE_ARC::ConvertToPolyline( double aAccuracy ) const
int n;
if( r < aAccuracy )
{
n = 0;
}
else
{
n = GetArcToSegmentCount( r, aAccuracy, ca );
r -= aAccuracy / 2; // Split the error on either side of arc
}
for( int i = 0; i <= n ; i++ )
// Split the error on either side of the arc. Since we want the start and end points
// to be exactly on the arc, the first and last segments need to be shorter to stay within
// the error band (since segments normally start 1/2 the error band outside the arc).
r += aAccuracy / 2;
n = n * 2;
rv.Append( m_start );
for( int i = 1; i < n ; i += 2 )
{
double a = sa;
@ -398,6 +401,8 @@ const SHAPE_LINE_CHAIN SHAPE_ARC::ConvertToPolyline( double aAccuracy ) const
rv.Append( KiROUND( x ), KiROUND( y ) );
}
rv.Append( m_end );
return rv;
}

55
qa/libs/kimath/geometry/test_shape_arc.cpp
View File

@ -493,11 +493,11 @@ struct ARC_TO_POLYLINE_CASE
* @param aPolyline the polyline to check
* @param aCentre the circle centre
* @param aRad the circle radius
* @param aTolEnds the tolerance for the endpoint-centre distance
* @param aTolerance the tolerance for the endpoint-centre distance
* @return true if predicate met
*/
bool ArePolylineEndPointsNearCircle(
const SHAPE_LINE_CHAIN& aPolyline, const VECTOR2I& aCentre, int aRad, int aTolEnds )
bool ArePolylineEndPointsNearCircle( const SHAPE_LINE_CHAIN& aPolyline, const VECTOR2I& aCentre,
int aRad, int aTolerance )
{
std::vector<VECTOR2I> points;
@ -506,7 +506,7 @@ bool ArePolylineEndPointsNearCircle(
points.push_back( aPolyline.CPoint( i ) );
}
return GEOM_TEST::ArePointsNearCircle( points, aCentre, aRad, aTolEnds );
return GEOM_TEST::ArePointsNearCircle( points, aCentre, aRad, aTolerance );
}
@ -519,8 +519,8 @@ bool ArePolylineEndPointsNearCircle(
* @param aTolEnds the tolerance for the midpoint-centre distance
* @return true if predicate met
*/
bool ArePolylineMidPointsNearCircle(
const SHAPE_LINE_CHAIN& aPolyline, const VECTOR2I& aCentre, int aRad, int aTolMidPts )
bool ArePolylineMidPointsNearCircle( const SHAPE_LINE_CHAIN& aPolyline, const VECTOR2I& aCentre,
int aRad, int aTolerance )
{
std::vector<VECTOR2I> points;
@ -530,7 +530,7 @@ bool ArePolylineMidPointsNearCircle(
points.push_back( mid_pt );
}
return GEOM_TEST::ArePointsNearCircle( points, aCentre, aRad, aTolMidPts );
return GEOM_TEST::ArePointsNearCircle( points, aCentre, aRad, aTolerance );
}
@ -549,17 +549,17 @@ BOOST_AUTO_TEST_CASE( ArcToPolyline )
"Semicircle",
{
{ 0, 0 },
{ -10, 0 },
{ -1000000, 0 },
180,
},
},
{
// check larger sizes still have required precisions
// and that reverse angles work too
"Larger semicircle",
// check that very small circles don't fall apart and that reverse angles
// work too
"Extremely small semicircle",
{
{ 0, 0 },
{ -10000, 0 },
{ -1000, 0 },
-180,
},
},
@ -568,44 +568,45 @@ BOOST_AUTO_TEST_CASE( ArcToPolyline )
"Non-round geometry",
{
{ 0, 0 },
{ -1234, 0 },
{ 1234567, 0 },
42.22,
},
},
};
const int width = 0;
const double accuracy = 1.0;
const int width = 0;
// Note: do not expect accuracies around 1 to work. We use integers internally so we're
// liable to rounding errors. In PCBNew accuracy defaults to 5000 and we don't recommend
// anything lower than 1000 (for performance reasons).
const int accuracy = 100;
const int epsilon = 1;
for( const auto& c : cases )
{
BOOST_TEST_CONTEXT( c.m_ctx_name )
{
const SHAPE_ARC this_arc{ c.m_geom.m_center_point, c.m_geom.m_start_point,
c.m_geom.m_center_angle, width };
c.m_geom.m_center_angle, width };
const SHAPE_LINE_CHAIN chain = this_arc.ConvertToPolyline( accuracy );
BOOST_TEST_MESSAGE( "Polyline has " << chain.PointCount() << " points" );
const int pt_tol = 1;
// Start point where expected
// Start point (exactly) where expected
BOOST_CHECK_EQUAL( chain.CPoint( 0 ), c.m_geom.m_start_point );
// End point where expected
BOOST_CHECK_PREDICATE( KI_TEST::IsVecWithinTol<VECTOR2I>,
( chain.CPoint( -1 ) )( this_arc.GetP1() )( pt_tol ) );
// End point (exactly) where expected
BOOST_CHECK_EQUAL( chain.CPoint( -1 ), this_arc.GetP1() );
const int radius = ( c.m_geom.m_center_point - c.m_geom.m_start_point ).EuclideanNorm();
int radius = ( c.m_geom.m_center_point - c.m_geom.m_start_point ).EuclideanNorm();
const int ep_tol = 2;
// Other points within accuracy + epsilon (for rounding) of where they should be
BOOST_CHECK_PREDICATE( ArePolylineEndPointsNearCircle,
( chain )( c.m_geom.m_center_point )( radius )( ep_tol ) );
( chain )( c.m_geom.m_center_point )( radius )( accuracy + epsilon ) );
const int mp_tol = 3;
BOOST_CHECK_PREDICATE( ArePolylineMidPointsNearCircle,
( chain )( c.m_geom.m_center_point )( radius )( mp_tol ) );
( chain )( c.m_geom.m_center_point )( radius )( accuracy + epsilon ) );
}
}
}