kicad/libs/kimath/include/geometry/geometry_utils.h

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