ar_autoplacer.cpp

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/*
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2012 Jean-Pierre Charras, [email protected]
 * Copyright (C) 2012 SoftPLC Corporation, Dick Hollenbeck <[email protected]>
 * Copyright (C) 2011 Wayne Stambaugh <[email protected]>
 *
 * Copyright (C) 1992-2023 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 <confirm.h>
#include <pcb_edit_frame.h>
#include <widgets/msgpanel.h>
#include <board.h>
#include <footprint.h>
#include <lset.h>
#include <pcb_shape.h>
#include <pad.h>
#include <board_commit.h>
#include <connectivity/connectivity_data.h>
#include <progress_reporter.h>
 
#include "ar_autoplacer.h"
#include "ar_matrix.h"
#include <memory>
#include <ratsnest/ratsnest_data.h>
 
#define AR_GAIN 16
#define AR_KEEPOUT_MARGIN 500
#define AR_ABORT_PLACEMENT -1
 
#define STEP_AR_MM 1.0
 
/* Bits characterizing cell */
#define CELL_IS_EMPTY 0x00
#define CELL_IS_HOLE 0x01 /* a conducting hole or obstacle */
#define CELL_IS_MODULE 0x02 /* auto placement occupied by a footprint */
#define CELL_IS_EDGE 0x20 /* Area and auto-placement: limiting cell contour (Board, Zone) */
#define CELL_IS_FRIEND 0x40 /* Area and auto-placement: cell part of the net */
#define CELL_IS_ZONE 0x80 /* Area and auto-placement: cell available */
 
 
AR_AUTOPLACER::AR_AUTOPLACER( BOARD* aBoard )
{
 m_board = aBoard;
 m_connectivity = std::make_unique<CONNECTIVITY_DATA>( );
 
 for( FOOTPRINT* footprint : m_board->Footprints() )
 m_connectivity->Add( footprint );
 
 m_gridSize = pcbIUScale.mmToIU( STEP_AR_MM );
 m_progressReporter = nullptr;
 m_refreshCallback = nullptr;
 m_minCost = 0.0;
}
 
 
void AR_AUTOPLACER::placeFootprint( FOOTPRINT* aFootprint, bool aDoNotRecreateRatsnest,
 const VECTOR2I& aPos )
{
 if( !aFootprint )
 return;
 
 aFootprint->SetPosition( aPos );
 m_connectivity->Update( aFootprint );
}
 
 
int AR_AUTOPLACER::genPlacementRoutingMatrix()
{
 m_matrix.UnInitRoutingMatrix();
 
 BOX2I bbox = m_board->GetBoardEdgesBoundingBox();
 
 if( bbox.GetWidth() == 0 || bbox.GetHeight() == 0 )
 return 0;
 
 // Build the board shape
 m_board->GetBoardPolygonOutlines( m_boardShape );
 m_topFreeArea = m_boardShape;
 m_bottomFreeArea = m_boardShape;
 
 m_matrix.ComputeMatrixSize( bbox );
 int nbCells = m_matrix.m_Ncols * m_matrix.m_Nrows;
 
 // Choose the number of board sides.
 m_matrix.m_RoutingLayersCount = 2;
 m_matrix.InitRoutingMatrix();
 m_matrix.m_routeLayerBottom = B_Cu;
 m_matrix.m_routeLayerTop = F_Cu;
 
 // Fill (mark) the cells inside the board:
 fillMatrix();
 
 // Other obstacles can be added here:
 for( auto drawing : m_board->Drawings() )
 {
 switch( drawing->Type() )
 {
 case PCB_SHAPE_T:
 if( drawing->GetLayer() != Edge_Cuts )
 {
 m_matrix.TraceSegmentPcb( (PCB_SHAPE*) drawing, CELL_IS_HOLE | CELL_IS_EDGE,
 m_matrix.m_GridRouting, AR_MATRIX::WRITE_CELL );
 }
 
 break;
 
 default:
 break;
 }
 }
 
 // Initialize top layer. to the same value as the bottom layer
 if( m_matrix.m_BoardSide[AR_SIDE_TOP] )
 memcpy( m_matrix.m_BoardSide[AR_SIDE_TOP], m_matrix.m_BoardSide[AR_SIDE_BOTTOM],
 nbCells * sizeof(AR_MATRIX::MATRIX_CELL) );
 
 return 1;
}
 
 
bool AR_AUTOPLACER::fillMatrix()
{
 std::vector <int> x_coordinates;
 bool success = true;
 int step = m_matrix.m_GridRouting;
 VECTOR2I coord_orgin = m_matrix.GetBrdCoordOrigin(); // Board coordinate of matruix cell (0,0)
 
 // Create a single board outline:
 SHAPE_POLY_SET brd_shape = m_boardShape.CloneDropTriangulation();
 brd_shape.Fracture( SHAPE_POLY_SET::PM_FAST );
 const SHAPE_LINE_CHAIN& outline = brd_shape.Outline(0);
 const BOX2I& rect = outline.BBox();
 
 // Creates the horizontal segments
 // Calculate the y limits of the area
 for( int refy = rect.GetY(), endy = rect.GetBottom(); refy < endy; refy += step )
 {
 // The row index (vertical position) of current line scan inside the placement matrix
 int idy = (refy - coord_orgin.y) / step;
 
 // Ensure we are still inside the placement matrix
 if( idy >= m_matrix.m_Nrows )
 break;
 
 // Ensure we are inside the placement matrix
 if( idy <= 0 )
 continue;
 
 // find all intersection points of an infinite line with polyline sides
 x_coordinates.clear();
 
 for( int v = 0; v < outline.PointCount(); v++ )
 {
 int seg_startX = outline.CPoint( v ).x;
 int seg_startY = outline.CPoint( v ).y;
 int seg_endX = outline.CPoint( v + 1 ).x;
 int seg_endY = outline.CPoint( v + 1 ).y;
 
 /* Trivial cases: skip if ref above or below the segment to test */
 if( ( seg_startY > refy ) && ( seg_endY > refy ) )
 continue;
 
 // segment below ref point, or its Y end pos on Y coordinate ref point: skip
 if( ( seg_startY <= refy ) && (seg_endY <= refy ) )
 continue;
 
 /* at this point refy is between seg_startY and seg_endY
 * see if an horizontal line at Y = refy is intersecting this segment
 */
 // calculate the x position of the intersection of this segment and the
 // infinite line this is more easier if we move the X,Y axis origin to
 // the segment start point:
 
 seg_endX -= seg_startX;
 seg_endY -= seg_startY;
 double newrefy = (double) ( refy - seg_startY );
 double intersec_x;
 
 if ( seg_endY == 0 ) // horizontal segment on the same line: skip
 continue;
 
 // Now calculate the x intersection coordinate of the horizontal line at
 // y = newrefy and the segment from (0,0) to (seg_endX,seg_endY) with the
 // horizontal line at the new refy position the line slope is:
 // slope = seg_endY/seg_endX; and inv_slope = seg_endX/seg_endY
 // and the x pos relative to the new origin is:
 // intersec_x = refy/slope = refy * inv_slope
 // Note: because horizontal segments are already tested and skipped, slope
 // exists (seg_end_y not O)
 double inv_slope = (double) seg_endX / seg_endY;
 intersec_x = newrefy * inv_slope;
 x_coordinates.push_back( (int) intersec_x + seg_startX );
 }
 
 // A line scan is finished: build list of segments
 
 // Sort intersection points by increasing x value:
 // So 2 consecutive points are the ends of a segment
 std::sort( x_coordinates.begin(), x_coordinates.end() );
 
 // An even number of coordinates is expected, because a segment has 2 ends.
 // An if this algorithm always works, it must always find an even count.
 if( ( x_coordinates.size() & 1 ) != 0 )
 {
 success = false;
 break;
 }
 
 // Fill cells having the same Y coordinate
 int iimax = x_coordinates.size() - 1;
 
 for( int ii = 0; ii < iimax; ii += 2 )
 {
 int seg_start_x = x_coordinates[ii] - coord_orgin.x;
 int seg_end_x = x_coordinates[ii + 1] - coord_orgin.x;
 
 // Fill cells at y coord = idy,
 // and at x cood >= seg_start_x and <= seg_end_x
 
 for( int idx = seg_start_x / step; idx < m_matrix.m_Ncols; idx++ )
 {
 if( idx * step > seg_end_x )
 break;
 
 if( idx * step >= seg_start_x )
 m_matrix.SetCell( idy, idx, AR_SIDE_BOTTOM, CELL_IS_ZONE );
 }
 }
 } // End examine segments in one area
 
 return success;
}
 
 
void AR_AUTOPLACER::addFpBody( const VECTOR2I& aStart, const VECTOR2I& aEnd, LSET aLayerMask )
{
 // Add a polygonal shape (rectangle) to m_fpAreaFront and/or m_fpAreaBack
 if( aLayerMask[ F_Cu ] )
 {
 m_fpAreaTop.NewOutline();
 m_fpAreaTop.Append( aStart.x, aStart.y );
 m_fpAreaTop.Append( aEnd.x, aStart.y );
 m_fpAreaTop.Append( aEnd.x, aEnd.y );
 m_fpAreaTop.Append( aStart.x, aEnd.y );
 }
 
 if( aLayerMask[ B_Cu ] )
 {
 m_fpAreaBottom.NewOutline();
 m_fpAreaBottom.Append( aStart.x, aStart.y );
 m_fpAreaBottom.Append( aEnd.x, aStart.y );
 m_fpAreaBottom.Append( aEnd.x, aEnd.y );
 m_fpAreaBottom.Append( aStart.x, aEnd.y );
 }
}
 
 
void AR_AUTOPLACER::addPad( PAD* aPad, int aClearance )
{
 // Add a polygonal shape (rectangle) to m_fpAreaFront and/or m_fpAreaBack
 BOX2I bbox = aPad->GetBoundingBox();
 bbox.Inflate( aClearance );
 
 if( aPad->IsOnLayer( F_Cu ) )
 {
 m_fpAreaTop.NewOutline();
 m_fpAreaTop.Append( bbox.GetLeft(), bbox.GetTop() );
 m_fpAreaTop.Append( bbox.GetRight(), bbox.GetTop() );
 m_fpAreaTop.Append( bbox.GetRight(), bbox.GetBottom() );
 m_fpAreaTop.Append( bbox.GetLeft(), bbox.GetBottom() );
 }
 
 if( aPad->IsOnLayer( B_Cu ) )
 {
 m_fpAreaBottom.NewOutline();
 m_fpAreaBottom.Append( bbox.GetLeft(), bbox.GetTop() );
 m_fpAreaBottom.Append( bbox.GetRight(), bbox.GetTop() );
 m_fpAreaBottom.Append( bbox.GetRight(), bbox.GetBottom() );
 m_fpAreaBottom.Append( bbox.GetLeft(), bbox.GetBottom() );
 }
}
 
 
void AR_AUTOPLACER::buildFpAreas( FOOTPRINT* aFootprint, int aFpClearance )
{
 m_fpAreaTop.RemoveAllContours();
 m_fpAreaBottom.RemoveAllContours();
 
 aFootprint->BuildCourtyardCaches();
 m_fpAreaTop = aFootprint->GetCourtyard( F_CrtYd );
 m_fpAreaBottom = aFootprint->GetCourtyard( B_CrtYd );
 
 LSET layerMask;
 
 if( aFootprint->GetLayer() == F_Cu )
 layerMask.set( F_Cu );
 
 if( aFootprint->GetLayer() == B_Cu )
 layerMask.set( B_Cu );
 
 BOX2I fpBBox = aFootprint->GetBoundingBox();
 
 fpBBox.Inflate( ( m_matrix.m_GridRouting / 2 ) + aFpClearance );
 
 // Add a minimal area to the fp area:
 addFpBody( fpBBox.GetOrigin(), fpBBox.GetEnd(), layerMask );
 
 // Trace pads + clearance areas.
 for( PAD* pad : aFootprint->Pads() )
 {
 int margin = (m_matrix.m_GridRouting / 2) + pad->GetOwnClearance( pad->GetLayer() );
 addPad( pad, margin );
 }
}
 
 
void AR_AUTOPLACER::genModuleOnRoutingMatrix( FOOTPRINT* Module )
{
 int ox, oy, fx, fy;
 LSET layerMask;
 BOX2I fpBBox = Module->GetBoundingBox();
 
 fpBBox.Inflate( m_matrix.m_GridRouting / 2 );
 ox = fpBBox.GetX();
 fx = fpBBox.GetRight();
 oy = fpBBox.GetY();
 fy = fpBBox.GetBottom();
 
 if( ox < m_matrix.m_BrdBox.GetX() )
 ox = m_matrix.m_BrdBox.GetX();
 
 if( ox > m_matrix.m_BrdBox.GetRight() )
 ox = m_matrix.m_BrdBox.GetRight();
 
 if( fx < m_matrix.m_BrdBox.GetX() )
 fx = m_matrix.m_BrdBox.GetX();
 
 if( fx > m_matrix.m_BrdBox.GetRight() )
 fx = m_matrix.m_BrdBox.GetRight();
 
 if( oy < m_matrix.m_BrdBox.GetY() )
 oy = m_matrix.m_BrdBox.GetY();
 
 if( oy > m_matrix.m_BrdBox.GetBottom() )
 oy = m_matrix.m_BrdBox.GetBottom();
 
 if( fy < m_matrix.m_BrdBox.GetY() )
 fy = m_matrix.m_BrdBox.GetY();
 
 if( fy > m_matrix.m_BrdBox.GetBottom() )
 fy = m_matrix.m_BrdBox.GetBottom();
 
 if( Module->GetLayer() == F_Cu )
 layerMask.set( F_Cu );
 
 if( Module->GetLayer() == B_Cu )
 layerMask.set( B_Cu );
 
 m_matrix.TraceFilledRectangle( ox, oy, fx, fy, layerMask,
 CELL_IS_MODULE, AR_MATRIX::WRITE_OR_CELL );
 
 // Trace pads + clearance areas.
 for( PAD* pad : Module->Pads() )
 {
 int margin = (m_matrix.m_GridRouting / 2) + pad->GetOwnClearance( pad->GetLayer() );
 m_matrix.PlacePad( pad, CELL_IS_MODULE, margin, AR_MATRIX::WRITE_OR_CELL );
 }
 
 // Trace clearance.
 int margin = ( m_matrix.m_GridRouting * Module->GetPadCount() ) / AR_GAIN;
 m_matrix.CreateKeepOutRectangle( ox, oy, fx, fy, margin, AR_KEEPOUT_MARGIN , layerMask );
 
 // Build the footprint courtyard
 buildFpAreas( Module, margin );
 
 // Substract the shape to free areas
 m_topFreeArea.BooleanSubtract( m_fpAreaTop, SHAPE_POLY_SET::PM_FAST );
 m_bottomFreeArea.BooleanSubtract( m_fpAreaBottom, SHAPE_POLY_SET::PM_FAST );
}
 
 
int AR_AUTOPLACER::testRectangle( const BOX2I& aRect, int side )
{
 BOX2I rect = aRect;
 
 rect.Inflate( m_matrix.m_GridRouting / 2 );
 
 VECTOR2I start = rect.GetOrigin();
 VECTOR2I end = rect.GetEnd();
 
 start -= m_matrix.m_BrdBox.GetOrigin();
 end -= m_matrix.m_BrdBox.GetOrigin();
 
 int row_min = start.y / m_matrix.m_GridRouting;
 int row_max = end.y / m_matrix.m_GridRouting;
 int col_min = start.x / m_matrix.m_GridRouting;
 int col_max = end.x / m_matrix.m_GridRouting;
 
 if( start.y > row_min * m_matrix.m_GridRouting )
 row_min++;
 
 if( start.x > col_min * m_matrix.m_GridRouting )
 col_min++;
 
 if( row_min < 0 )
 row_min = 0;
 
 if( row_max >= ( m_matrix.m_Nrows - 1 ) )
 row_max = m_matrix.m_Nrows - 1;
 
 if( col_min < 0 )
 col_min = 0;
 
 if( col_max >= ( m_matrix.m_Ncols - 1 ) )
 col_max = m_matrix.m_Ncols - 1;
 
 for( int row = row_min; row <= row_max; row++ )
 {
 for( int col = col_min; col <= col_max; col++ )
 {
 unsigned int data = m_matrix.GetCell( row, col, side );
 
 if( ( data & CELL_IS_ZONE ) == 0 )
 return AR_OUT_OF_BOARD;
 
 if( (data & CELL_IS_MODULE) )
 return AR_OCCUIPED_BY_MODULE;
 }
 }
 
 return AR_FREE_CELL;
}
 
 
unsigned int AR_AUTOPLACER::calculateKeepOutArea( const BOX2I& aRect, int side )
{
 VECTOR2I start = aRect.GetOrigin();
 VECTOR2I end = aRect.GetEnd();
 
 start -= m_matrix.m_BrdBox.GetOrigin();
 end -= m_matrix.m_BrdBox.GetOrigin();
 
 int row_min = start.y / m_matrix.m_GridRouting;
 int row_max = end.y / m_matrix.m_GridRouting;
 int col_min = start.x / m_matrix.m_GridRouting;
 int col_max = end.x / m_matrix.m_GridRouting;
 
 if( start.y > row_min * m_matrix.m_GridRouting )
 row_min++;
 
 if( start.x > col_min * m_matrix.m_GridRouting )
 col_min++;
 
 if( row_min < 0 )
 row_min = 0;
 
 if( row_max >= ( m_matrix.m_Nrows - 1 ) )
 row_max = m_matrix.m_Nrows - 1;
 
 if( col_min < 0 )
 col_min = 0;
 
 if( col_max >= ( m_matrix.m_Ncols - 1 ) )
 col_max = m_matrix.m_Ncols - 1;
 
 unsigned int keepOutCost = 0;
 
 for( int row = row_min; row <= row_max; row++ )
 {
 for( int col = col_min; col <= col_max; col++ )
 {
 // m_matrix.GetDist returns the "cost" of the cell
 // at position (row, col)
 // in autoplace this is the cost of the cell, if it is
 // inside aRect
 keepOutCost += m_matrix.GetDist( row, col, side );
 }
 }
 
 return keepOutCost;
}
 
 
int AR_AUTOPLACER::testFootprintOnBoard( FOOTPRINT* aFootprint, bool TstOtherSide,
 const VECTOR2I& aOffset )
{
 int side = AR_SIDE_TOP;
 int otherside = AR_SIDE_BOTTOM;
 
 if( aFootprint->GetLayer() == B_Cu )
 {
 side = AR_SIDE_BOTTOM; otherside = AR_SIDE_TOP;
 }
 
 BOX2I fpBBox = aFootprint->GetBoundingBox( false, false );
 fpBBox.Move( -1*aOffset );
 
 buildFpAreas( aFootprint, 0 );
 
 int diag = //testModuleByPolygon( aFootprint, side, aOffset );
 testRectangle( fpBBox, side );
 
 if( diag != AR_FREE_CELL )
 return diag;
 
 if( TstOtherSide )
 {
 diag = //testModuleByPolygon( aFootprint, otherside, aOffset );
 testRectangle( fpBBox, otherside );
 
 if( diag != AR_FREE_CELL )
 return diag;
 }
 
 int marge = ( m_matrix.m_GridRouting * aFootprint->GetPadCount() ) / AR_GAIN;
 
 fpBBox.Inflate( marge );
 return calculateKeepOutArea( fpBBox, side );
}
 
 
int AR_AUTOPLACER::getOptimalFPPlacement( FOOTPRINT* aFootprint )
{
 int error = 1;
 VECTOR2I lastPosOK;
 double min_cost, curr_cost, Score;
 bool testOtherSide;
 
 lastPosOK = m_matrix.m_BrdBox.GetOrigin();
 
 VECTOR2I fpPos = aFootprint->GetPosition();
 BOX2I fpBBox = aFootprint->GetBoundingBox( false, false );
 
 // Move fpBBox to have the footprint position at (0,0)
 fpBBox.Move( -fpPos );
 VECTOR2I fpBBoxOrg = fpBBox.GetOrigin();
 
 // Calculate the limit of the footprint position, relative to the routing matrix area
 VECTOR2I xylimit = m_matrix.m_BrdBox.GetEnd() - fpBBox.GetEnd();
 
 VECTOR2I initialPos = m_matrix.m_BrdBox.GetOrigin() - fpBBoxOrg;
 
 // Stay on grid.
 initialPos.x -= initialPos.x % m_matrix.m_GridRouting;
 initialPos.y -= initialPos.y % m_matrix.m_GridRouting;
 
 m_curPosition = initialPos;
 VECTOR2I fpOffset = fpPos - m_curPosition;
 
 // Examine pads, and set testOtherSide to true if a footprint has at least 1 pad through.
 testOtherSide = false;
 
 if( m_matrix.m_RoutingLayersCount > 1 )
 {
 LSET other( aFootprint->GetLayer() == B_Cu ? F_Cu : B_Cu );
 
 for( PAD* pad : aFootprint->Pads() )
 {
 if( !( pad->GetLayerSet() & other ).any() )
 continue;
 
 testOtherSide = true;
 break;
 }
 }
 
 fpBBox.SetOrigin( fpBBoxOrg + m_curPosition );
 
 min_cost = -1.0;
// m_frame->SetStatusText( wxT( "Score ??, pos ??" ) );
 
 
 for( ; m_curPosition.x < xylimit.x; m_curPosition.x += m_matrix.m_GridRouting )
 {
 m_curPosition.y = initialPos.y;
 
 for( ; m_curPosition.y < xylimit.y; m_curPosition.y += m_matrix.m_GridRouting )
 {
 
 fpBBox.SetOrigin( fpBBoxOrg + m_curPosition );
 fpOffset = fpPos - m_curPosition;
 int keepOutCost = testFootprintOnBoard( aFootprint, testOtherSide, fpOffset );
 
 if( keepOutCost >= 0 ) // i.e. if the footprint can be put here
 {
 error = 0;
 // m_frame->build_ratsnest_footprint( aFootprint ); // fixme
 curr_cost = computePlacementRatsnestCost( aFootprint, fpOffset );
 Score = curr_cost + keepOutCost;
 
 if( (min_cost >= Score ) || (min_cost < 0 ) )
 {
 lastPosOK = m_curPosition;
 min_cost = Score;
/*
 wxString msg;
 msg.Printf( wxT( "Score %g, pos %s, %s" ),
 min_cost,
 ::CoordinateToString( LastPosOK.x ),
 ::CoordinateToString( LastPosOK.y ) );
 m_frame->SetStatusText( msg );*/
 }
 }
 }
 }
 
 // Regeneration of the modified variable.
 m_curPosition = lastPosOK;
 
 m_minCost = min_cost;
 return error;
}
 
 
const PAD* AR_AUTOPLACER::nearestPad( FOOTPRINT* aRefFP, PAD* aRefPad, const VECTOR2I& aOffset )
{
 const PAD* nearest = nullptr;
 int64_t nearestDist = INT64_MAX;
 
 for( FOOTPRINT* footprint : m_board->Footprints() )
 {
 if ( footprint == aRefFP )
 continue;
 
 if( !m_matrix.m_BrdBox.Contains( footprint->GetPosition() ) )
 continue;
 
 for( PAD* pad: footprint->Pads() )
 {
 if( pad->GetNetCode() != aRefPad->GetNetCode() || pad->GetNetCode() <= 0 )
 continue;
 
 auto dist = ( VECTOR2I( aRefPad->GetPosition() - aOffset ) -
 VECTOR2I( pad->GetPosition() ) ).EuclideanNorm();
 
 if ( dist < nearestDist )
 {
 nearestDist = dist;
 nearest = pad;
 }
 }
 }
 
 return nearest;
}
 
 
double AR_AUTOPLACER::computePlacementRatsnestCost( FOOTPRINT* aFootprint, const VECTOR2I& aOffset )
{
 double curr_cost;
 VECTOR2I start; // start point of a ratsnest
 VECTOR2I end; // end point of a ratsnest
 int dx, dy;
 
 curr_cost = 0;
 
 for( PAD* pad : aFootprint->Pads() )
 {
 const PAD* nearest = nearestPad( aFootprint, pad, aOffset );
 
 if( !nearest )
 continue;
 
 start = VECTOR2I( pad->GetPosition() ) - VECTOR2I(aOffset);
 end = VECTOR2I( nearest->GetPosition() );
 
 //m_overlay->SetIsStroke( true );
 //m_overlay->SetStrokeColor( COLOR4D(0.0, 1.0, 0.0, 1.0) );
 //m_overlay->Line( start, end );
 
 // Cost of the ratsnest.
 dx = end.x - start.x;
 dy = end.y - start.y;
 
 dx = abs( dx );
 dy = abs( dy );
 
 // ttry to have always dx >= dy to calculate the cost of the ratsnest
 if( dx < dy )
 std::swap( dx, dy );
 
 // Cost of the connection = length + penalty due to the slope
 // dx is the biggest length relative to the X or Y axis
 // the penalty is max for 45 degrees ratsnests,
 // and 0 for horizontal or vertical ratsnests.
 // For Horizontal and Vertical ratsnests, dy = 0;
 double conn_cost = hypot( dx, dy * 2.0 );
 curr_cost += conn_cost; // Total cost = sum of costs of each connection
 }
 
 return curr_cost;
}
 
 
// Sort routines
static bool sortFootprintsByComplexity( FOOTPRINT* ref, FOOTPRINT* compare )
{
 double ff1, ff2;
 
 ff1 = ref->GetArea() * ref->GetPadCount();
 ff2 = compare->GetArea() * compare->GetPadCount();
 
 return ff2 < ff1;
}
 
 
static bool sortFootprintsByRatsnestSize( FOOTPRINT* ref, FOOTPRINT* compare )
{
 double ff1, ff2;
 
 ff1 = ref->GetArea() * ref->GetFlag();
 ff2 = compare->GetArea() * compare->GetFlag();
 return ff2 < ff1;
}
 
 
FOOTPRINT* AR_AUTOPLACER::pickFootprint()
{
 std::vector<FOOTPRINT*> fpList;
 
 
 for( FOOTPRINT* footprint : m_board->Footprints() )
 fpList.push_back( footprint );
 
 sort( fpList.begin(), fpList.end(), sortFootprintsByComplexity );
 
 for( unsigned kk = 0; kk < fpList.size(); kk++ )
 {
 FOOTPRINT* footprint = fpList[kk];
 footprint->SetFlag( 0 );
 
 if( !footprint->NeedsPlaced() )
 continue;
 
 m_connectivity->Update( footprint );
 }
 
 m_connectivity->RecalculateRatsnest();
 
 for( unsigned kk = 0; kk < fpList.size(); kk++ )
 {
 FOOTPRINT* footprint = fpList[kk];
 
 auto edges = m_connectivity->GetRatsnestForComponent( footprint, true );
 
 footprint->SetFlag( edges.size() ) ;
 }
 
 sort( fpList.begin(), fpList.end(), sortFootprintsByRatsnestSize );
 
 // Search for "best" footprint.
 FOOTPRINT* bestFootprint = nullptr;
 FOOTPRINT* altFootprint = nullptr;
 
 for( unsigned ii = 0; ii < fpList.size(); ii++ )
 {
 FOOTPRINT* footprint = fpList[ii];
 
 if( !footprint->NeedsPlaced() )
 continue;
 
 altFootprint = footprint;
 
 if( footprint->GetFlag() == 0 )
 continue;
 
 bestFootprint = footprint;
 break;
 }
 
 if( bestFootprint )
 return bestFootprint;
 else
 return altFootprint;
}
 
 
void AR_AUTOPLACER::drawPlacementRoutingMatrix( )
{
 // Draw the board free area
 m_overlay->Clear();
 m_overlay->SetIsFill( true );
 m_overlay->SetIsStroke( false );
 
 SHAPE_POLY_SET freeArea = m_topFreeArea.CloneDropTriangulation();
 freeArea.Fracture( SHAPE_POLY_SET::PM_FAST );
 
 // Draw the free polygon areas, top side:
 if( freeArea.OutlineCount() > 0 )
 {
 m_overlay->SetIsFill( true );
 m_overlay->SetIsStroke( false );
 m_overlay->SetFillColor( COLOR4D(0.7, 0.0, 0.1, 0.2) );
 m_overlay->Polygon( freeArea );
 }
 
 freeArea = m_bottomFreeArea;
 freeArea.Fracture( SHAPE_POLY_SET::PM_FAST );
 
 // Draw the free polygon areas, bottom side:
 if( freeArea.OutlineCount() > 0 )
 {
 m_overlay->SetFillColor( COLOR4D(0.0, 0.7, 0.0, 0.2) );
 m_overlay->Polygon( freeArea );
 }
}
 
 
AR_RESULT AR_AUTOPLACER::AutoplaceFootprints( std::vector<FOOTPRINT*>& aFootprints,
 BOARD_COMMIT* aCommit,
 bool aPlaceOffboardModules )
{
 VECTOR2I memopos;
 int error;
 bool cancelled = false;
 
 memopos = m_curPosition;
 
 m_matrix.m_GridRouting = m_gridSize; //(int) m_frame->GetScreen()->GetGridSize().x;
 
 // Ensure Board.m_GridRouting has a reasonable value:
 if( m_matrix.m_GridRouting < pcbIUScale.mmToIU( 0.25 ) )
 m_matrix.m_GridRouting = pcbIUScale.mmToIU( 0.25 );
 
 // Compute footprint parameters used in autoplace
 if( genPlacementRoutingMatrix( ) == 0 )
 return AR_FAILURE;
 
 int placedCount = 0;
 
 for( FOOTPRINT* footprint : m_board->Footprints() )
 footprint->SetNeedsPlaced( false );
 
 std::vector<FOOTPRINT*> offboardMods;
 
 if( aPlaceOffboardModules )
 {
 for( FOOTPRINT* footprint : m_board->Footprints() )
 {
 if( !m_matrix.m_BrdBox.Contains( footprint->GetPosition() ) )
 offboardMods.push_back( footprint );
 }
 }
 
 for( FOOTPRINT* footprint : aFootprints )
 {
 footprint->SetNeedsPlaced( true );
 aCommit->Modify( footprint );
 }
 
 for( FOOTPRINT* footprint : offboardMods )
 {
 footprint->SetNeedsPlaced( true );
 aCommit->Modify( footprint );
 }
 
 for( FOOTPRINT* footprint : m_board->Footprints() )
 {
 if( footprint->NeedsPlaced() ) // Erase from screen
 placedCount++;
 else
 genModuleOnRoutingMatrix( footprint );
 }
 
 if( m_progressReporter )
 {
 m_progressReporter->Report( _( "Autoplacing components..." ) );
 m_progressReporter->SetMaxProgress( placedCount );
 }
 
 drawPlacementRoutingMatrix();
 
 if( m_refreshCallback )
 m_refreshCallback( nullptr );
 
 FOOTPRINT* footprint;
 
 while( ( footprint = pickFootprint() ) != nullptr )
 {
 // Display some info about activity, footprint placement can take a while:
 
 if( m_progressReporter )
 m_progressReporter->SetTitle( wxString::Format( _( "Autoplacing %s" ),
 footprint->GetReference() ) );
 
 error = getOptimalFPPlacement( footprint );
 
 if( error == AR_ABORT_PLACEMENT )
 break;
 
 // Place footprint.
 placeFootprint( footprint, true, m_curPosition );
 
 genModuleOnRoutingMatrix( footprint );
 footprint->SetIsPlaced( true );
 footprint->SetNeedsPlaced( false );
 drawPlacementRoutingMatrix();
 
 if( m_refreshCallback )
 m_refreshCallback( footprint );
 
 if( m_progressReporter )
 {
 m_progressReporter->AdvanceProgress();
 
 if ( !m_progressReporter->KeepRefreshing( false ) )
 {
 cancelled = true;
 break;
 }
 }
 }
 
 m_curPosition = memopos;
 
 m_matrix.UnInitRoutingMatrix();
 
 return cancelled ? AR_CANCELLED : AR_COMPLETED;
}