66 lines
2.5 KiB
C++
66 lines
2.5 KiB
C++
/*
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* This program source code file is part of KiCad, a free EDA CAD application.
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*
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* Copyright (C) 2018 Jean-Pierre Charras, jp.charras at wanadoo.fr
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* Copyright (C) 1992-2018 KiCad Developers, see AUTHORS.txt for contributors.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, you may find one here:
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* http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
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* or you may search the http://www.gnu.org website for the version 2 license,
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* or you may write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
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*/
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/**
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* @file geometry_utils.cpp
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* @brief a few functions useful in geometry calculations.
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*/
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#include <math.h>
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#include <common.h>
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#include <geometry/geometry_utils.h>
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int GetArcToSegmentCount( int aRadius, int aErrorMax, double aArcAngleDegree )
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{
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// calculate the number of segments to approximate a circle by segments
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// given the max distance between the middle of a segment and the circle
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// error relative to the radius value:
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double rel_error = (double)aErrorMax / aRadius;
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// minimal arc increment in degrees:
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double step = 180 / M_PI * acos( 1.0 - rel_error ) * 2;
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// the minimal seg count for a arc
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int segCount = KiROUND( fabs( aArcAngleDegree ) / step );
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// Ensure at least one segment is used
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return std::max( segCount, 1 );
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}
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double GetCircletoPolyCorrectionFactor( int aSegCountforCircle )
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{
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/* calculates the coeff to compensate radius reduction of circle
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* due to the segment approx.
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* For a circle the min radius is radius * cos( 2PI / aSegCountforCircle / 2)
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* this is the distance between the center and the middle of the segment.
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* therfore, to move the middle of the segment to the circle (distance = radius)
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* the correctionFactor is 1 /cos( PI/aSegCountforCircle )
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*/
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double correctionFactor = 1.0 / cos( M_PI / aSegCountforCircle );
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return correctionFactor;
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}
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