trigo.cpp

Go to the documentation of this file.

/*
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2014 Jean-Pierre Charras, jp.charras at wanadoo.fr
 * Copyright (C) 2014-2022 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
 */
 
#include <limits> // for numeric_limits
#include <stdlib.h> // for abs
#include <type_traits> // for swap
 
#include <geometry/seg.h>
#include <math/util.h>
#include <math/vector2d.h> // for VECTOR2I
#include <trigo.h>
 
// Returns true if the point P is on the segment S.
// faster than TestSegmentHit() because P should be exactly on S
// therefore works fine only for H, V and 45 deg segm (suitable for wires in eeschema)
bool IsPointOnSegment( const VECTOR2I& aSegStart, const VECTOR2I& aSegEnd,
 const VECTOR2I& aTestPoint )
{
 VECTOR2I vectSeg = aSegEnd - aSegStart; // Vector from S1 to S2
 VECTOR2I vectPoint = aTestPoint - aSegStart; // Vector from S1 to P
 
 // Use long long here to avoid overflow in calculations
 if( (long long) vectSeg.x * vectPoint.y - (long long) vectSeg.y * vectPoint.x )
 return false; /* Cross product non-zero, vectors not parallel */
 
 if( ( (long long) vectSeg.x * vectPoint.x + (long long) vectSeg.y * vectPoint.y ) <
 ( (long long) vectPoint.x * vectPoint.x + (long long) vectPoint.y * vectPoint.y ) )
 return false; /* Point not on segment */
 
 return true;
}
 
 
// Returns true if the segment 1 intersected the segment 2.
bool SegmentIntersectsSegment( const VECTOR2I& a_p1_l1, const VECTOR2I& a_p2_l1,
 const VECTOR2I& a_p1_l2, const VECTOR2I& a_p2_l2,
 VECTOR2I* aIntersectionPoint )
{
 
 //We are forced to use 64bit ints because the internal units can overflow 32bit ints when
 // multiplied with each other, the alternative would be to scale the units down (i.e. divide
 // by a fixed number).
 int64_t dX_a, dY_a, dX_b, dY_b, dX_ab, dY_ab;
 int64_t num_a, num_b, den;
 
 //Test for intersection within the bounds of both line segments using line equations of the
 // form:
 // x_k(u_k) = u_k * dX_k + x_k(0)
 // y_k(u_k) = u_k * dY_k + y_k(0)
 // with 0 <= u_k <= 1 and k = [ a, b ]
 
 dX_a = int64_t{ a_p2_l1.x } - a_p1_l1.x;
 dY_a = int64_t{ a_p2_l1.y } - a_p1_l1.y;
 dX_b = int64_t{ a_p2_l2.x } - a_p1_l2.x;
 dY_b = int64_t{ a_p2_l2.y } - a_p1_l2.y;
 dX_ab = int64_t{ a_p1_l2.x } - a_p1_l1.x;
 dY_ab = int64_t{ a_p1_l2.y } - a_p1_l1.y;
 
 den = dY_a * dX_b - dY_b * dX_a ;
 
 //Check if lines are parallel
 if( den == 0 )
 return false;
 
 num_a = dY_ab * dX_b - dY_b * dX_ab;
 num_b = dY_ab * dX_a - dY_a * dX_ab;
 
 // Only compute the intersection point if requested
 if( aIntersectionPoint )
 {
 *aIntersectionPoint = a_p1_l1;
 aIntersectionPoint->x += KiROUND( dX_a * ( double )num_a / ( double )den );
 aIntersectionPoint->y += KiROUND( dY_a * ( double )num_b / ( double )den );
 }
 
 if( den < 0 )
 {
 den = -den;
 num_a = -num_a;
 num_b = -num_b;
 }
 
 //Test sign( u_a ) and return false if negative
 if( num_a < 0 )
 return false;
 
 //Test sign( u_b ) and return false if negative
 if( num_b < 0 )
 return false;
 
 //Test to ensure (u_a <= 1)
 if( num_a > den )
 return false;
 
 //Test to ensure (u_b <= 1)
 if( num_b > den )
 return false;
 
 return true;
}
 
 
bool TestSegmentHit( const VECTOR2I& aRefPoint, const VECTOR2I& aStart, const VECTOR2I& aEnd,
 int aDist )
{
 int xmin = aStart.x;
 int xmax = aEnd.x;
 int ymin = aStart.y;
 int ymax = aEnd.y;
 VECTOR2I delta = aStart - aRefPoint;
 
 if( xmax < xmin )
 std::swap( xmax, xmin );
 
 if( ymax < ymin )
 std::swap( ymax, ymin );
 
 // First, check if we are outside of the bounding box
 if( ( ymin - aRefPoint.y > aDist ) || ( aRefPoint.y - ymax > aDist ) )
 return false;
 
 if( ( xmin - aRefPoint.x > aDist ) || ( aRefPoint.x - xmax > aDist ) )
 return false;
 
 // Next, eliminate easy cases
 if( aStart.x == aEnd.x && aRefPoint.y > ymin && aRefPoint.y < ymax )
 return std::abs( delta.x ) <= aDist;
 
 if( aStart.y == aEnd.y && aRefPoint.x > xmin && aRefPoint.x < xmax )
 return std::abs( delta.y ) <= aDist;
 
 SEG segment( aStart, aEnd );
 return segment.SquaredDistance( aRefPoint ) < SEG::Square( aDist + 1 );
}
 
 
const VECTOR2I CalcArcMid( const VECTOR2I& aStart, const VECTOR2I& aEnd, const VECTOR2I& aCenter,
 bool aMinArcAngle )
{
 VECTOR2I startVector = aStart - aCenter;
 VECTOR2I endVector = aEnd - aCenter;
 
 EDA_ANGLE startAngle( startVector );
 EDA_ANGLE endAngle( endVector );
 EDA_ANGLE midPointRotAngle = ( startAngle - endAngle ).Normalize180() / 2;
 
 if( !aMinArcAngle )
 midPointRotAngle += ANGLE_180;
 
 VECTOR2I newMid = aStart;
 RotatePoint( newMid, aCenter, midPointRotAngle );
 
 return newMid;
}
 
 
void RotatePoint( int* pX, int* pY, const EDA_ANGLE& aAngle )
{
 VECTOR2I pt;
 EDA_ANGLE angle = aAngle;
 
 angle.Normalize();
 
 // Cheap and dirty optimizations for 0, 90, 180, and 270 degrees.
 if( angle == ANGLE_0 )
 {
 pt = VECTOR2I( *pX, *pY );
 }
 else if( angle == ANGLE_90 ) /* sin = 1, cos = 0 */
 {
 pt = VECTOR2I( *pY, -*pX );
 }
 else if( angle == ANGLE_180 ) /* sin = 0, cos = -1 */
 {
 pt = VECTOR2I( -*pX, -*pY );
 }
 else if( angle == ANGLE_270 ) /* sin = -1, cos = 0 */
 {
 pt = VECTOR2I( -*pY, *pX );
 }
 else
 {
 double sinus = angle.Sin();
 double cosinus = angle.Cos();
 
 pt.x = KiROUND( ( *pY * sinus ) + ( *pX * cosinus ) );
 pt.y = KiROUND( ( *pY * cosinus ) - ( *pX * sinus ) );
 }
 
 *pX = pt.x;
 *pY = pt.y;
}
 
 
void RotatePoint( int* pX, int* pY, int cx, int cy, const EDA_ANGLE& angle )
{
 int ox, oy;
 
 ox = *pX - cx;
 oy = *pY - cy;
 
 RotatePoint( &ox, &oy, angle );
 
 *pX = ox + cx;
 *pY = oy + cy;
}
 
 
void RotatePoint( double* pX, double* pY, double cx, double cy, const EDA_ANGLE& angle )
{
 double ox, oy;
 
 ox = *pX - cx;
 oy = *pY - cy;
 
 RotatePoint( &ox, &oy, angle );
 
 *pX = ox + cx;
 *pY = oy + cy;
}
 
 
void RotatePoint( double* pX, double* pY, const EDA_ANGLE& aAngle )
{
 EDA_ANGLE angle = aAngle;
 VECTOR2D pt;
 
 angle.Normalize();
 
 // Cheap and dirty optimizations for 0, 90, 180, and 270 degrees.
 if( angle == ANGLE_0 )
 {
 pt = VECTOR2D( *pX, *pY );
 }
 else if( angle == ANGLE_90 ) /* sin = 1, cos = 0 */
 {
 pt = VECTOR2D( *pY, -*pX );
 }
 else if( angle == ANGLE_180 ) /* sin = 0, cos = -1 */
 {
 pt = VECTOR2D( -*pX, -*pY );
 }
 else if( angle == ANGLE_270 ) /* sin = -1, cos = 0 */
 {
 pt = VECTOR2D( -*pY, *pX );
 }
 else
 {
 double sinus = angle.Sin();
 double cosinus = angle.Cos();
 
 pt.x = ( *pY * sinus ) + ( *pX * cosinus );
 pt.y = ( *pY * cosinus ) - ( *pX * sinus );
 }
 
 *pX = pt.x;
 *pY = pt.y;
}
 
 
const VECTOR2D CalcArcCenter( const VECTOR2D& aStart, const VECTOR2D& aEnd,
 const EDA_ANGLE& aAngle )
{
 EDA_ANGLE angle( aAngle );
 VECTOR2I start = aStart;
 VECTOR2I end = aEnd;
 
 if( angle < ANGLE_0 )
 {
 std::swap( start, end );
 angle = -angle;
 }
 
 if( angle > ANGLE_180 )
 {
 std::swap( start, end );
  angle = ANGLE_360 - angle;
 }
 
 double chord = ( start - end ).EuclideanNorm();
 double r = ( chord / 2.0 ) / ( angle / 2.0 ).Sin();
 double d_squared = r * r - chord* chord / 4.0;
 double d = 0.0;
 
 if( d_squared > 0.0 )
 d = sqrt( d_squared );
 
 VECTOR2D vec2 = (end - start).Resize( d );
 VECTOR2D vc = (end - start).Resize( chord / 2 );
 
 RotatePoint( vec2, -ANGLE_90 );
 
 return VECTOR2D( start + vc + vec2 );
}
 
 
const VECTOR2D CalcArcCenter( const VECTOR2D& aStart, const VECTOR2D& aMid, const VECTOR2D& aEnd )
{
 VECTOR2D center;
 double yDelta_21 = aMid.y - aStart.y;
 double xDelta_21 = aMid.x - aStart.x;
 double yDelta_32 = aEnd.y - aMid.y;
 double xDelta_32 = aEnd.x - aMid.x;
 
 // This is a special case for aMid as the half-way point when aSlope = 0 and bSlope = inf
 // or the other way around. In that case, the center lies in a straight line between
 // aStart and aEnd
 if( ( ( xDelta_21 == 0.0 ) && ( yDelta_32 == 0.0 ) ) ||
 ( ( yDelta_21 == 0.0 ) && ( xDelta_32 == 0.0 ) ) )
 {
 center.x = ( aStart.x + aEnd.x ) / 2.0;
 center.y = ( aStart.y + aEnd.y ) / 2.0 ;
 return center;
 }
 
 // Prevent div=0 errors
 if( xDelta_21 == 0.0 )
  xDelta_21 = std::numeric_limits<double>::epsilon();
 
 if( xDelta_32 == 0.0 )
 xDelta_32 = -std::numeric_limits<double>::epsilon();
 
 double aSlope = yDelta_21 / xDelta_21;
 double bSlope = yDelta_32 / xDelta_32;
 
 double daSlope = aSlope * VECTOR2D( 0.5 / yDelta_21, 0.5 / xDelta_21 ).EuclideanNorm();
 double dbSlope = bSlope * VECTOR2D( 0.5 / yDelta_32, 0.5 / xDelta_32 ).EuclideanNorm();
 
 if( aSlope == bSlope )
 {
 if( aStart == aEnd )
 {
 // This is a special case for a 360 degrees arc. In this case, the center is halfway between
 // the midpoint and either end point
 center.x = ( aStart.x + aMid.x ) / 2.0;
 center.y = ( aStart.y + aMid.y ) / 2.0 ;
 return center;
 }
 else
 {
 // If the points are colinear, the center is at infinity, so offset
 // the slope by a minimal amount
 // Warning: This will induce a small error in the center location
 aSlope += std::numeric_limits<double>::epsilon();
 bSlope -= std::numeric_limits<double>::epsilon();
 }
 }
 
 // Prevent divide by zero error
 if( aSlope == 0.0 )
 aSlope = std::numeric_limits<double>::epsilon();
 
 // What follows is the calculation of the center using the slope of the two lines as well as
 // the propagated error that occurs when rounding to the nearest nanometer. The error can be
 // ±0.5 units but can add up to multiple nanometers after the full calculation is performed.
 // All variables starting with `d` are the delta of that variable. This is approximately equal
 // to the standard deviation.
 // We ignore the possible covariance between variables. We also truncate our series expansion
 // at the first term. These are reasonable assumptions as the worst-case scenario is that we
 // underestimate the potential uncertainty, which would potentially put us back at the status quo
 double abSlopeStartEndY = aSlope * bSlope * ( aStart.y - aEnd.y );
 double dabSlopeStartEndY = abSlopeStartEndY * std::sqrt( ( daSlope / aSlope * daSlope / aSlope )
  + ( dbSlope / bSlope * dbSlope / bSlope )
 + ( M_SQRT1_2 / ( aStart.y - aEnd.y )
 * M_SQRT1_2 / ( aStart.y - aEnd.y ) ) );
 
 double bSlopeStartMidX = bSlope * ( aStart.x + aMid.x );
 double dbSlopeStartMidX = bSlopeStartMidX * std::sqrt( ( dbSlope / bSlope * dbSlope / bSlope )
 + ( M_SQRT1_2 / ( aStart.x + aMid.x )
 * M_SQRT1_2 / ( aStart.x + aMid.x ) ) );
 
 double aSlopeMidEndX = aSlope * ( aMid.x + aEnd.x );
 double daSlopeMidEndX = aSlopeMidEndX * std::sqrt( ( daSlope / aSlope * daSlope / aSlope )
 + ( M_SQRT1_2 / ( aMid.x + aEnd.x )
 * M_SQRT1_2 / ( aMid.x + aEnd.x ) ) );
 
 double twiceBASlopeDiff = 2 * ( bSlope - aSlope );
 double dtwiceBASlopeDiff = 2 * std::sqrt( dbSlope * dbSlope + daSlope * daSlope );
 
 double centerNumeratorX = abSlopeStartEndY + bSlopeStartMidX - aSlopeMidEndX;
 double dCenterNumeratorX = std::sqrt( dabSlopeStartEndY * dabSlopeStartEndY
 + dbSlopeStartMidX * dbSlopeStartMidX
 + daSlopeMidEndX * daSlopeMidEndX );
 
 double centerX = ( abSlopeStartEndY + bSlopeStartMidX - aSlopeMidEndX ) / twiceBASlopeDiff;
 
 double dCenterX = centerX * std::sqrt( ( dCenterNumeratorX / centerNumeratorX * dCenterNumeratorX / centerNumeratorX )
 + ( dtwiceBASlopeDiff / twiceBASlopeDiff * dtwiceBASlopeDiff / twiceBASlopeDiff ) );
 
 
 double centerNumeratorY = ( ( aStart.x + aMid.x ) / 2.0 - centerX );
 double dCenterNumeratorY = std::sqrt( 1.0 / 8.0 + dCenterX * dCenterX );
 
 double centerFirstTerm = centerNumeratorY / aSlope;
 double dcenterFirstTermY = centerFirstTerm * std::sqrt(
 ( dCenterNumeratorY/ centerNumeratorY * dCenterNumeratorY / centerNumeratorY )
 + ( daSlope / aSlope * daSlope / aSlope ) );
 
 double centerY = centerFirstTerm + ( aStart.y + aMid.y ) / 2.0;
 double dCenterY = std::sqrt( dcenterFirstTermY * dcenterFirstTermY + 1.0 / 8.0 );
 
 double rounded100CenterX = std::floor( ( centerX + 50.0 ) / 100.0 ) * 100.0;
 double rounded100CenterY = std::floor( ( centerY + 50.0 ) / 100.0 ) * 100.0;
 double rounded10CenterX = std::floor( ( centerX + 5.0 ) / 10.0 ) * 10.0;
 double rounded10CenterY = std::floor( ( centerY + 5.0 ) / 10.0 ) * 10.0;
 
 // The last step is to find the nice, round numbers near our baseline estimate and see if they are within our uncertainty
 // range. If they are, then we use this round value as the true value. This is justified because ALL values within the
 // uncertainty range are equally true. Using a round number will make sure that we are on a multiple of 1mil or 100nm
 // when calculating centers.
 if( std::abs( rounded100CenterX - centerX ) < dCenterX && std::abs( rounded100CenterY - centerY ) < dCenterY )
 {
 center.x = rounded100CenterX;
 center.y = rounded100CenterY;
 }
 else if( std::abs( rounded10CenterX - centerX ) < dCenterX && std::abs( rounded10CenterY - centerY ) < dCenterY )
 {
 center.x = rounded10CenterX;
 center.y = rounded10CenterY;
 }
 else
 {
 center.x = centerX;
 center.y = centerY;
 }
 
 
 return center;
}
 
 
const VECTOR2I CalcArcCenter( const VECTOR2I& aStart, const VECTOR2I& aMid, const VECTOR2I& aEnd )
{
 VECTOR2D dStart( static_cast<double>( aStart.x ), static_cast<double>( aStart.y ) );
 VECTOR2D dMid( static_cast<double>( aMid.x ), static_cast<double>( aMid.y ) );
 VECTOR2D dEnd( static_cast<double>( aEnd.x ), static_cast<double>( aEnd.y ) );
 VECTOR2D dCenter = CalcArcCenter( dStart, dMid, dEnd );
 
 VECTOR2I iCenter;
 
 iCenter.x = KiROUND( Clamp<double>( double( std::numeric_limits<int>::min() / 2.0 ),
 dCenter.x,
 double( std::numeric_limits<int>::max() / 2.0 ) ) );
 
 iCenter.y = KiROUND( Clamp<double>( double( std::numeric_limits<int>::min() / 2.0 ),
 dCenter.y,
 double( std::numeric_limits<int>::max() / 2.0 ) ) );
 
 return iCenter;
}