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geometry/geometry_utils.cpp: Fix a minimal value (6) to calculate the segments by circle count to approximate a circle. 

Use also this minimal value to calculate  the circle to poly correction factor
Also, remove a useless code.
This commit is contained in:
jean-pierre charras 2019-04-02 09:03:47 +02:00
parent abc605fcfa
commit 0d2dd48cad
1 changed files with 21 additions and 10 deletions
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31
common/geometry/geometry_utils.cpp
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@ -2,7 +2,7 @@
* This program source code file is part of KiCad, a free EDA CAD application.
*
* Copyright (C) 2018 Jean-Pierre Charras, jp.charras at wanadoo.fr
* Copyright (C) 1992-2018 KiCad Developers, see AUTHORS.txt for contributors.
* Copyright (C) 1992-2019 KiCad Developers, see AUTHORS.txt for contributors.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
@ -30,6 +30,9 @@
#include <eda_rect.h>
#include <geometry/geometry_utils.h>
// To approximate a circle by segments, a minimal seg count is mandatory
#define MIN_SEGCOUNT_FOR_CIRCLE 6
int GetArcToSegmentCount( int aRadius, int aErrorMax, double aArcAngleDegree )
{
// calculate the number of segments to approximate a circle by segments
@ -38,11 +41,15 @@ int GetArcToSegmentCount( int aRadius, int aErrorMax, double aArcAngleDegree )
// error relative to the radius value:
double rel_error = (double)aErrorMax / aRadius;
// minimal arc increment in degrees:
double step = 180 / M_PI * acos( 1.0 - rel_error ) * 2;
// the minimal seg count for a arc
int segCount = round_nearest( fabs( aArcAngleDegree ) / step );
double arc_increment = 180 / M_PI * acos( 1.0 - rel_error ) * 2;
// Ensure at least one segment is used
// Ensure a minimal arc increment reasonable value for a circle
// (360.0 degrees). For very small radius values, this is mandatory.
arc_increment = std::min( 360.0/MIN_SEGCOUNT_FOR_CIRCLE, arc_increment );
int segCount = round_nearest( fabs( aArcAngleDegree ) / arc_increment );
// Ensure at least one segment is used (can happen for small arcs)
return std::max( segCount, 1 );
}
@ -53,13 +60,13 @@ double GetCircletoPolyCorrectionFactor( int aSegCountforCircle )
* due to the segment approx.
* For a circle the min radius is radius * cos( 2PI / aSegCountforCircle / 2)
* this is the distance between the center and the middle of the segment.
* therfore, to move the middle of the segment to the circle (distance = radius)
* therefore, to move the middle of the segment to the circle (distance = radius)
* the correctionFactor is 1 /cos( PI/aSegCountforCircle )
*/
if( aSegCountforCircle < 6 )
aSegCountforCircle = 6;
if( 1 || aSegCountforCircle > 64 )
return 1.0 / cos( M_PI / aSegCountforCircle );
if( aSegCountforCircle < MIN_SEGCOUNT_FOR_CIRCLE )
aSegCountforCircle = MIN_SEGCOUNT_FOR_CIRCLE;
return 1.0 / cos( M_PI / aSegCountforCircle );
}
@ -70,16 +77,19 @@ double GetCircletoPolyCorrectionFactor( int aSegCountforCircle )
inline int clipOutCode( const EDA_RECT *aClipBox, int x, int y )
{
int code;
if( y < aClipBox->GetY() )
code = 2;
else if( y > aClipBox->GetBottom() )
code = 1;
else
code = 0;
if( x < aClipBox->GetX() )
code |= 4;
else if( x > aClipBox->GetRight() )
code |= 8;
return code;
}
@ -98,6 +108,7 @@ bool ClipLine( const EDA_RECT *aClipBox, int &x1, int &y1, int &x2, int &y2 )
// Choose a side to clip
int thisoutcode, x, y;
if( outcode1 )
thisoutcode = outcode1;
else