140 lines
4.4 KiB
C++
140 lines
4.4 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.h
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* @brief a few functions useful in geometry calculations.
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*/
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#ifndef GEOMETRY_UTILS_H
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#define GEOMETRY_UTILS_H
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#include <math/vector2d.h>
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class EDA_RECT;
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/**
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* @return the number of segments to approximate a arc by segments
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* with a given max error (this number is >= 1)
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* @param aRadius is the radius od the circle or arc
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* @param aErrorMax is the max error
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* This is the max distance between the middle of a segment and the circle.
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* @param aArcAngleDegree is the arc angle in degrees
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*/
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int GetArcToSegmentCount( int aRadius, int aErrorMax, double aArcAngleDegree );
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/**
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* @return the correction factor to approximate a circle by segments
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* @param aSegCountforCircle is the number of segments to approximate the circle
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*
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* When creating a polygon from a circle, the polygon is inside the circle.
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* Only corners are on the circle.
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* This is incorrect when building clearance areas of circles, that need to build
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* the equivalent polygon outside the circle
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* The correction factor is a scaling factor to apply to the radius to build a
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* polygon outside the circle (only the middle of each segment is on the circle
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*/
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double GetCircletoPolyCorrectionFactor( int aSegCountforCircle );
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/**
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* Snap a vector onto the nearest 0, 45 or 90 degree line.
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*
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* The magnitude of the vector is NOT kept, instead the co-ordinates are
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* set equal (and/or opposite) or to zero as needed. The effect of this is
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* that if the starting vector is on a square grid, the resulting snapped
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* vector will still be on the same grid.
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* @param a vector to be snapped
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* @return the snapped vector
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*/
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template<typename T>
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VECTOR2<T> GetVectorSnapped45( const VECTOR2<T>& aVec )
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{
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auto newVec = aVec;
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const VECTOR2<T> absVec { std::abs( aVec.x ), std::abs( aVec.y ) };
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if ( absVec.x > absVec.y * 2 )
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{
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// snap along x-axis
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newVec.y = 0;
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}
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else if ( absVec.y > absVec.x * 2 )
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{
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// snap onto y-axis
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newVec.x = 0;
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}
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else if ( absVec.x > absVec.y )
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{
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// snap away from x-axis towards 45
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newVec.y = std::copysign( aVec.x, aVec.y );
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} else
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{
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// snap away from y-axis towards 45
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newVec.x = std::copysign( aVec.y, aVec.x );
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}
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return newVec;
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}
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/**
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* Test if any part of a line falls within the bounds of a rectangle.
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*
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* Please note that this is only accurate for lines that are one pixel wide.
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*
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* @param aClipBox - The rectangle to test.
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* @param x1 - X coordinate of one end of a line.
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* @param y1 - Y coordinate of one end of a line.
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* @param x2 - X coordinate of the other end of a line.
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* @param y2 - Y coordinate of the other end of a line.
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*
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* @return - False if any part of the line lies within the rectangle.
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*/
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bool ClipLine( const EDA_RECT *aClipBox, int &x1, int &y1, int &x2, int &y2 );
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/**
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* Dashed and dotted line patterns.
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*
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* Note: these are all macros because they're included from files with different
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* IU definitions.
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*/
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#define DOT_WIDTH_MILS 0.0254
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#define DOT_MARK_LEN( aLineWidth ) \
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( std::max( 1.0, IU_PER_MILS * DOT_WIDTH_MILS - aLineWidth ) )
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#define DASH_GAP_LEN( aLineWidth ) \
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( 3.0 * DOT_MARK_LEN( aLineWidth ) + ( 2.0 * aLineWidth ) )
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#define DASH_MARK_LEN( aLineWidth ) \
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( std::max( DASH_GAP_LEN( aLineWidth ), 5.0 * DOT_MARK_LEN( aLineWidth ) ) )
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#endif // #ifndef GEOMETRY_UTILS_H
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