66 lines
2.5 KiB
C++
66 lines
2.5 KiB
C++
/*
|
|
* 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.
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License
|
|
* as published by the Free Software Foundation; either version 2
|
|
* of the License, or (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, you may find one here:
|
|
* http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
|
|
* or you may search the http://www.gnu.org website for the version 2 license,
|
|
* or you may write to the Free Software Foundation, Inc.,
|
|
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
|
|
*/
|
|
|
|
/**
|
|
* @file geometry_utils.cpp
|
|
* @brief a few functions useful in geometry calculations.
|
|
*/
|
|
|
|
#include <math.h>
|
|
#include <common.h>
|
|
#include <geometry/geometry_utils.h>
|
|
|
|
int GetArcToSegmentCount( int aRadius, int aErrorMax, double aArcAngleDegree )
|
|
{
|
|
// calculate the number of segments to approximate a circle by segments
|
|
// given the max distance between the middle of a segment and the circle
|
|
|
|
// 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 = KiROUND( fabs( aArcAngleDegree ) / step );
|
|
|
|
// Ensure at least one segment is used
|
|
return std::max( segCount, 1 );
|
|
}
|
|
|
|
|
|
double GetCircletoPolyCorrectionFactor( int aSegCountforCircle )
|
|
{
|
|
/* calculates the coeff to compensate radius reduction of circle
|
|
* 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)
|
|
* the correctionFactor is 1 /cos( PI/aSegCountforCircle )
|
|
*/
|
|
if( aSegCountforCircle < 6 )
|
|
aSegCountforCircle = 6;
|
|
if( 1 || aSegCountforCircle > 64 )
|
|
return 1.0 / cos( M_PI / aSegCountforCircle );
|
|
}
|
|
|