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

553 lines
16 KiB
C++

/*
* This program source code file is part of KICAD, a free EDA CAD application.
*
* Copyright (C) 2016-2017 CERN
* @author Tomasz Wlostowski <tomasz.wlostowski@cern.ch>
*
* 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
*/
#ifndef __POLY_GRID_PARTITION_H
#define __POLY_GRID_PARTITION_H
#include <algorithm>
#include <functional>
#include <set>
#include <unordered_map>
#include <vector>
#include <geometry/seg.h>
#include <geometry/shape_line_chain.h>
#include <geometry/shape_rect.h>
#include <math/util.h>
#include <math/vector2d.h>
/**
* Class POLY_GRID_PARTITION
*
* Provides a fast test for point inside polygon.
*
* Takes a large poly and splits it into a grid of rectangular cells, forming a spatial hash table.
* Each cell contains only the edges that 'touch it' (any point of the edge belongs to the cell).
* Edges can be marked as leading or trailing. Leading edge indicates that space to the left of it (x-wise) is outside the polygon.
* Trailing edge, conversely, means space to the right is outside the polygon.
* The point inside check for point (p) works as follows:
* - determine the cell coordinates of (p) (poly2grid)
* - find the matching grid cell ( O(0), if the cell coordinates are outside the range, the point is not in the polygon )
* - if the cell contains edges, find the first edge to the left or right of the point, whichever comes first.
* - if the edge to the left is the 'lead edge', the point is inside. if it's a trailing edge, the point is outside.
* - idem for the edge to the right of (p), just reverse the edge types
* - if the cell doesn't contain any edges, scan horizontal cells to the left and right (switching sides with each iteration)
* until an edge if found.
* NOTE: the rescale_trunc() function is used for grid<->world coordinate conversion because it rounds towards 0 (not to nearest)
* It's important as rouding to nearest (which the standard rescale() function does) will shift the grid by half a cell.
*/
class POLY_GRID_PARTITION
{
public:
POLY_GRID_PARTITION( const SHAPE_LINE_CHAIN& aPolyOutline, int gridSize )
{
build( aPolyOutline, gridSize );
}
int ContainsPoint( const VECTOR2I& aP, int aClearance = 0 ) // const
{
if( containsPoint(aP) )
return 1;
if( aClearance > 0 )
return checkClearance ( aP, aClearance );
return 0;
}
const BOX2I& BBox() const
{
return m_bbox;
}
private:
enum HASH_FLAG
{
LEAD_EDGE = 1,
TRAIL_EDGE = 2,
};
using EDGE_LIST = std::vector<int>;
template <class T>
inline void hash_combine( std::size_t& seed, const T& v )
{
std::hash<T> hasher;
seed ^= hasher( v ) + 0x9e3779b9 + (seed << 6) + (seed >> 2);
}
struct segsEqual
{
bool operator()( const SEG& a, const SEG& b ) const
{
return (a.A == b.A && a.B == b.B) || (a.A == b.B && a.B == b.A);
}
};
struct segHash
{
std::size_t operator()( const SEG& a ) const
{
return a.A.x + a.B.x + a.A.y + a.B.y;
}
};
int containsPoint( const VECTOR2I& aP, bool debug = false ) const
{
const auto gridPoint = poly2grid( aP );
if( !m_bbox.Contains( aP ) )
return 0;
SCAN_STATE state;
const EDGE_LIST& cell = m_grid[ m_gridSize * gridPoint.y + gridPoint.x ];
scanCell( state, cell, aP, gridPoint.x, gridPoint.y );
if( state.nearest < 0 )
{
state = SCAN_STATE();
for( int d = 1; d <= m_gridSize; d++ )
{
int xl = gridPoint.x - d;
int xh = gridPoint.x + d;
if( xl >= 0 )
{
const EDGE_LIST& cell2 = m_grid[ m_gridSize * gridPoint.y + xl ];
scanCell( state, cell2, aP, xl, gridPoint.y );
if( state.nearest >= 0 )
break;
}
if( xh < m_gridSize )
{
const EDGE_LIST& cell2 = m_grid[ m_gridSize * gridPoint.y + xh ];
scanCell( state, cell2, aP, xh, gridPoint.y );
if( state.nearest >= 0 )
break;
}
}
}
#ifdef TOM_EXTRA_VERBOSE
printf("Nearest: %d prev: %d dmax %d\n", state.nearest, state.nearest_prev, state.dist_max );
#endif
if( state.nearest < 0 )
return 0;
if( state.dist_max == 0 )
return 1;
// special case for diagonal 'slits', e.g. two segments that partially overlap each other.
// Just love handling degeneracy... As I can't find any reliable way of fixing it for the moment,
// let's fall back to the good old O(N) point-in-polygon test
if( state.nearest_prev >= 0 && state.dist_max == state.dist_prev )
{
int d = std::abs( state.nearest_prev - state.nearest );
if( (d == 1) && ( (m_flags[state.nearest_prev] & m_flags[state.nearest]) == 0 ) )
{
return m_outline.PointInside( aP );
}
}
if( state.dist_max > 0 )
{
return m_flags[state.nearest] & LEAD_EDGE ? 1 : 0;
}
else
{
return m_flags[state.nearest] & TRAIL_EDGE ? 1 : 0;
}
}
bool checkClearance( const VECTOR2I& aP, int aClearance )
{
int gx0 = poly2gridX( aP.x - aClearance - 1);
int gx1 = poly2gridX( aP.x + aClearance + 1);
int gy0 = poly2gridY( aP.y - aClearance - 1);
int gy1 = poly2gridY( aP.y + aClearance + 1);
using ecoord = VECTOR2I::extended_type;
ecoord dist = (ecoord) aClearance * aClearance;
for ( int gx = gx0; gx <= gx1; gx++ )
{
for ( int gy = gy0; gy <= gy1; gy++ )
{
const auto& cell = m_grid [ m_gridSize * gy + gx];
for ( auto index : cell )
{
const auto& seg = m_outline.Segment( index );
if ( seg.SquaredDistance(aP) <= dist )
return true;
}
}
}
return false;
}
int rescale_trunc( int aNumerator, int aValue, int aDenominator ) const
{
int64_t numerator = (int64_t) aNumerator * (int64_t) aValue;
return numerator / aDenominator;
}
// convertes grid cell coordinates to the polygon coordinates
const VECTOR2I grid2poly( const VECTOR2I& p ) const
{
int px = rescale_trunc( p.x, m_bbox.GetWidth(), m_gridSize ) + m_bbox.GetPosition().x;
int py = rescale_trunc( p.y, m_bbox.GetHeight(), m_gridSize ) + m_bbox.GetPosition().y;
return VECTOR2I( px, py );
}
void stupid_test() const
{
for(int i = 0; i < 16;i++)
assert( poly2gridX(grid2polyX(i)) == i);
}
int grid2polyX( int x ) const
{
return rescale_trunc( x, m_bbox.GetWidth(), m_gridSize ) + m_bbox.GetPosition().x;
}
int grid2polyY( int y ) const
{
return rescale_trunc( y, m_bbox.GetHeight(), m_gridSize ) + m_bbox.GetPosition().y;
}
const VECTOR2I poly2grid( const VECTOR2I& p ) const
{
int px = rescale_trunc( p.x - m_bbox.GetPosition().x, m_gridSize, m_bbox.GetWidth() );
int py = rescale_trunc( p.y - m_bbox.GetPosition().y, m_gridSize, m_bbox.GetHeight() );
if( px < 0 )
px = 0;
if( px >= m_gridSize )
px = m_gridSize - 1;
if( py < 0 )
py = 0;
if( py >= m_gridSize )
py = m_gridSize - 1;
return VECTOR2I( px, py );
}
int poly2gridX( int x ) const
{
int px = rescale_trunc( x - m_bbox.GetPosition().x, m_gridSize, m_bbox.GetWidth() );
if( px < 0 )
px = 0;
if( px >= m_gridSize )
px = m_gridSize - 1;
return px;
}
int poly2gridY( int y ) const
{
int py = rescale_trunc( y - m_bbox.GetPosition().y, m_gridSize, m_bbox.GetHeight() );
if( py < 0 )
py = 0;
if( py >= m_gridSize )
py = m_gridSize - 1;
return py;
}
void build( const SHAPE_LINE_CHAIN& aPolyOutline, int gridSize )
{
m_outline = aPolyOutline;
//if (orientation(m_outline) < 0)
// m_outline = m_outline.Reverse();
m_bbox = m_outline.BBox();
m_gridSize = gridSize;
m_outline.SetClosed( true );
m_grid.reserve( gridSize * gridSize );
for( int y = 0; y < gridSize; y++ )
{
for( int x = 0; x < gridSize; x++ )
{
m_grid.emplace_back( );
}
}
VECTOR2I ref_v( 0, 1 );
VECTOR2I ref_h( 0, 1 );
m_flags.reserve( m_outline.SegmentCount() );
std::unordered_map<SEG, int, segHash, segsEqual> edgeSet;
for( int i = 0; i<m_outline.SegmentCount(); i++ )
{
SEG edge = m_outline.Segment( i );
if( edgeSet.find( edge ) == edgeSet.end() )
{
edgeSet[edge] = 1;
}
else
{
edgeSet[edge]++;
}
}
for( int i = 0; i<m_outline.SegmentCount(); i++ )
{
auto edge = m_outline.Segment( i );
auto dir = edge.B - edge.A;
int flags = 0;
if ( dir.y == 0 )
{
flags = 0;
}
else if( edgeSet[edge] == 1 )
{
if( dir.Dot( ref_h ) < 0 )
{
flags |= LEAD_EDGE;
}
else if( dir.Dot( ref_h ) > 0 )
{
flags |= TRAIL_EDGE;
}
}
m_flags.push_back( flags );
if( edge.A.y == edge.B.y )
continue;
std::set<int> indices;
indices.insert( m_gridSize * poly2gridY( edge.A.y ) + poly2gridX( edge.A.x ) );
indices.insert( m_gridSize * poly2gridY( edge.B.y ) + poly2gridX( edge.B.x ) );
if( edge.A.x > edge.B.x )
std::swap( edge.A, edge.B );
dir = edge.B - edge.A;
if( dir.x != 0 )
{
int gx0 = poly2gridX( edge.A.x );
int gx1 = poly2gridX( edge.B.x );
for( int x = gx0; x <= gx1; x++ )
{
int px = grid2polyX( x );
int py = ( edge.A.y + rescale_trunc( dir.y, px - edge.A.x, dir.x ) );
int yy = poly2gridY( py );
indices.insert( m_gridSize * yy + x );
if( x > 0 )
indices.insert( m_gridSize * yy + x - 1 );
}
}
if( edge.A.y > edge.B.y )
std::swap( edge.A, edge.B );
dir = edge.B - edge.A;
if( dir.y != 0 )
{
int gy0 = poly2gridY( edge.A.y );
int gy1 = poly2gridY( edge.B.y );
for( int y = gy0; y <= gy1; y++ )
{
int py = grid2polyY( y );
int px = ( edge.A.x + rescale_trunc( dir.x, py - edge.A.y, dir.y ) );
int xx = poly2gridX( px );
indices.insert( m_gridSize * y + xx );
if( y > 0 )
indices.insert( m_gridSize * (y - 1) + xx );
}
}
for( auto idx : indices )
m_grid[idx].push_back( i );
}
}
bool inRange( int v1, int v2, int x ) const
{
if( v1 < v2 )
{
return x >= v1 && x <= v2;
}
return x >= v2 && x <= v1;
}
struct SCAN_STATE
{
SCAN_STATE()
{
dist_prev = INT_MAX;
dist_max = INT_MAX;
nearest = -1;
nearest_prev = -1;
};
int dist_prev;
int dist_max;
int nearest_prev;
int nearest;
};
void scanCell( SCAN_STATE& state, const EDGE_LIST& cell, const VECTOR2I& aP, int cx, int cy ) const
{
int cx0 = grid2polyX(cx);
int cx1 = grid2polyX(cx + 1);
#ifdef TOM_EXTRA_VERBOSE
printf("Scan %d %d\n", cx, cy );
#endif
for( auto index : cell )
{
const SEG& edge = m_outline.CSegment( index );
if( m_flags[index] == 0 )
{
if ( aP.y == edge.A.y && inRange( edge.A.x, edge.B.x, aP.x ) ) // we belong to the outline
{
state.nearest = index;
state.dist_max = 0;
return;
} else {
continue;
}
}
if( inRange( edge.A.y, edge.B.y, aP.y ) )
{
#ifdef TOM_EXTRA_VERBOSE
printf("Test edge: %d [%d %d %d %d] p %d %d flags %d\n", index, edge.A.x, edge.A.y, edge.B.x, edge.B.y, aP.x, aP.y );
#endif
int dist = 0;
int x0;
if( edge.A.y == aP.y )
{
x0 = edge.A.x;
}
else if( edge.B.y == aP.y )
{
x0 = edge.B.x;
}
else
{
x0 = edge.A.x + rescale( ( edge.B.x - edge.A.x ), (aP.y - edge.A.y), (edge.B.y - edge.A.y ) );
}
dist = aP.x - x0;
#ifdef TOM_EXTRA_VERBOSE
printf(" x0 %d dist %d [%s]\n", x0, dist, x0 < cx0 || x0 > cx1 ? "outside" : "inside" );
#endif
if( x0 < cx0 || x0 > cx1 )
{
continue;
}
if( dist == 0 )
{
if( state.nearest_prev < 0 || state.nearest != index )
{
state.dist_prev = state.dist_max;
state.nearest_prev = state.nearest;
}
state.nearest = index;
state.dist_max = 0;
return;
}
if( dist != 0 && std::abs( dist ) <= std::abs( state.dist_max ) )
{
if( state.nearest_prev < 0 || state.nearest != index )
{
state.dist_prev = state.dist_max;
state.nearest_prev = state.nearest;
}
state.dist_max = dist;
state.nearest = index;
}
}
}
}
private:
int m_gridSize;
SHAPE_LINE_CHAIN m_outline;
BOX2I m_bbox;
std::vector<int> m_flags;
std::vector<EDGE_LIST> m_grid;
};
#endif