oval.cpp

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/*
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2014 CERN
 * Copyright (C) 2018-2023 KiCad Developers, see AUTHORS.txt for contributors.
 * @author Tomasz Wlostowski <[email protected]>
 *
 * 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
 */
 
#include "geometry/oval.h"
 
#include <trigo.h> // for RotatePoint
 
 
std::vector<VECTOR2I> GetOvalKeyPoints( const VECTOR2I& aOvalSize, const EDA_ANGLE& aRotation,
 OVAL_KEY_POINT_FLAGS aFlags )
{
 const VECTOR2I half_size = aOvalSize / 2;
 const int half_width = std::min( half_size.x, half_size.y );
 const int half_len = std::max( half_size.x, half_size.y );
 
 // Points on a non-rotated pad at the origin, long-axis is y
 // (so for now, width is left/right, len is up/down)
 std::vector<VECTOR2I> pts;
 
 if ( aFlags & OVAL_CENTER )
 {
 // Centre is easy
 pts.emplace_back( 0, 0 );
 };
 
 if ( aFlags & OVAL_SIDE_MIDPOINTS )
 {
 // Side midpoints
 pts.emplace_back( half_width, 0 );
 pts.emplace_back( -half_width, 0 );
 }
 
 if ( aFlags & OVAL_CAP_TIPS )
 {
 // Cap ends
 pts.emplace_back( 0, half_len );
 pts.emplace_back( 0, -half_len );
 }
 
 // Distance from centre to cap centres
 const int d_centre_to_cap_centre = half_len - half_width;
 
 if ( aFlags & OVAL_CAP_CENTERS )
 {
 // Cap centres
 pts.emplace_back( 0, d_centre_to_cap_centre );
 pts.emplace_back( 0, -d_centre_to_cap_centre );
 }
 
 if ( aFlags & OVAL_SIDE_ENDS )
 {
 // End points of flat sides (always vertical)
 pts.emplace_back( half_width, d_centre_to_cap_centre );
 pts.emplace_back( half_width, -d_centre_to_cap_centre );
 pts.emplace_back( -half_width, d_centre_to_cap_centre );
 pts.emplace_back( -half_width, -d_centre_to_cap_centre );
 }
 
 // If the pad is horizontal (i.e. x > y), we'll rotate the whole thing
 // 90 degrees and work with it as if it was vertical
 const bool swap_xy = half_size.x > half_size.y;
 const EDA_ANGLE rotation = aRotation + ( swap_xy ? -ANGLE_90 : ANGLE_0 );
 
 // Add the quadrant points to the caps only if rotated
 // (otherwise they're just the tips)
 if( ( aFlags & OVAL_CARDINAL_EXTREMES ) && !rotation.IsCardinal() )
 {
 // We need to find two perpendicular lines from the centres
 // of each cap to the cap edge, which will hit the points
 // where the cap is tangent to H/V lines when rotated into place.
 //
 // Because we know the oval is always vertical, this means the
 // two lines are formed between _|, through \/ to |_
 // where the apex is the cap centre.
 
 // The vector from a cap centre to the tip (i.e. vertical)
 const VECTOR2I cap_radial = { 0, half_width };
 
 // Rotate in the opposite direction to the oval's rotation
 // (that will be unwound later)
 EDA_ANGLE radial_line_rotation = -rotation;
 
 radial_line_rotation.Normalize90();
 
 VECTOR2I cap_radial_to_x_axis = cap_radial;
 RotatePoint( cap_radial_to_x_axis, radial_line_rotation );
 
 // Find the other line - it's 90 degrees away, but re-normalise
 // as it could be to the left or right
 radial_line_rotation -= ANGLE_90;
 radial_line_rotation.Normalize90();
 
 VECTOR2I cap_radial_to_y_axis = cap_radial;
 RotatePoint( cap_radial_to_y_axis, radial_line_rotation );
 
 // The quadrant points are then the relevant offsets from each cap centre
 pts.emplace_back( VECTOR2I{ 0, d_centre_to_cap_centre } + cap_radial_to_y_axis );
 pts.emplace_back( VECTOR2I{ 0, d_centre_to_cap_centre } + cap_radial_to_x_axis );
 // The opposite cap offsets go from the other cap centre, the other way
 pts.emplace_back( VECTOR2I{ 0, -d_centre_to_cap_centre } - cap_radial_to_y_axis );
 pts.emplace_back( VECTOR2I{ 0, -d_centre_to_cap_centre } - cap_radial_to_x_axis );
 }
 
 for( VECTOR2I& pt : pts )
 {
 // Transform to the actual orientation
 // Already includes the extra 90 to swap x/y if needed
 RotatePoint( pt, rotation );
 }
 
 return pts;
}