kicad/3d-viewer/3d_rendering/3d_render_raytracing/shapes2D/cpolygon2d.cpp

/*
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2015-2016 Mario Luzeiro <mrluzeiro@ua.pt>
 * 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  cpolygon2d.cpp
 * @brief
 */

#include "cpolygon2d.h"
#include <wx/debug.h>
#include <fctsys.h>

#ifdef PRINT_STATISTICS_3D_VIEWER
#include <stdio.h>
#endif

// CPOLYGONBLOCK2D
// /////////////////////////////////////////////////////////////////////////////

static bool polygon_IsPointInside( const SEGMENTS &aSegments, const SFVEC2F &aPoint )
{
    wxASSERT( aSegments.size() >= 3 );

    unsigned int i;
    unsigned int j = aSegments.size() - 1;
    bool  oddNodes = false;

    for( i = 0; i < aSegments.size(); j = i++ )
    {
        const float polyJY = aSegments[j].m_Start.y;
        const float polyIY = aSegments[i].m_Start.y;

        if( ((polyIY <= aPoint.y) && (polyJY >= aPoint.y)) ||
            ((polyJY <= aPoint.y) && (polyIY >= aPoint.y))
          )
        {
            const float polyJX = aSegments[j].m_Start.x;
            const float polyIX = aSegments[i].m_Start.x;

            if( (polyIX <= aPoint.x) || (polyJX <= aPoint.x) )
                oddNodes ^= ( ( polyIX +
                                ( ( aPoint.y - polyIY ) *
                                  aSegments[i].m_inv_JY_minus_IY ) *
                               aSegments[i].m_JX_minus_IX ) < aPoint.x );
        }
    }

    return oddNodes;
}


CPOLYGONBLOCK2D::CPOLYGONBLOCK2D( const SEGMENTS_WIDTH_NORMALS& aOpenSegmentList,
        const OUTERS_AND_HOLES& aOuter_and_holes, const BOARD_ITEM& aBoardItem )
        : COBJECT2D( OBJECT2D_TYPE::POLYGON, aBoardItem )
{
    m_open_segments.resize( aOpenSegmentList.size() );

    // Copy vectors and structures
    for( unsigned int i = 0; i < aOpenSegmentList.size(); i++ )
        m_open_segments[i] = aOpenSegmentList[i];

    m_outers_and_holes = aOuter_and_holes;

    // Compute bounding box with the points of the polygon
    m_bbox.Reset();

    for( unsigned int i = 0; i < m_outers_and_holes.m_Outers.size(); i++ )
    {
        for( unsigned int j = 0; j < m_outers_and_holes.m_Outers[i].size(); j++ )
            m_bbox.Union( ((SEGMENTS)m_outers_and_holes.m_Outers[i])[j].m_Start );
    }

    m_bbox.ScaleNextUp();
    m_centroid = m_bbox.GetCenter();

    // Some checks
    wxASSERT( m_open_segments.size() ==  aOpenSegmentList.size() );
    wxASSERT( m_open_segments.size() > 0 );

    wxASSERT( m_outers_and_holes.m_Outers.size() > 0 );
    wxASSERT( m_outers_and_holes.m_Outers.size() == aOuter_and_holes.m_Outers.size() );
    wxASSERT( m_outers_and_holes.m_Holes.size()  == aOuter_and_holes.m_Holes.size() );

    wxASSERT( m_outers_and_holes.m_Outers[0].size() >= 3 );
    wxASSERT( m_outers_and_holes.m_Outers[0].size() ==
              aOuter_and_holes.m_Outers[0].size() );

    wxASSERT( m_bbox.IsInitialized() );
}


bool CPOLYGONBLOCK2D::Intersects( const CBBOX2D &aBBox ) const
{
    return m_bbox.Intersects( aBBox );

    // !TODO: this is a quick not perfect implementation
    // in order to make it perfect the box must be checked against all the
    // polygons in the outers and not inside the holes
}


bool CPOLYGONBLOCK2D::Overlaps( const CBBOX2D &aBBox ) const
{
    // NOT IMPLEMENTED
    return false;
}


bool CPOLYGONBLOCK2D::Intersect( const RAYSEG2D &aSegRay,
                                 float *aOutT,
                                 SFVEC2F *aNormalOut ) const
{
    int hitIndex = -1;
    float hitU = 0.0f;
    float tMin = 0.0f;

    for( unsigned int i = 0; i < m_open_segments.size(); i++ )
    {
        const SFVEC2F &s = m_open_segments[i].m_Precalc_slope;
        const SFVEC2F &q = m_open_segments[i].m_Start;

        float rxs = aSegRay.m_End_minus_start.x * s.y -
                    aSegRay.m_End_minus_start.y * s.x;

        if( fabs(rxs) >  FLT_EPSILON )
        {
            const float inv_rxs = 1.0f / rxs;

            const SFVEC2F pq = q - aSegRay.m_Start;

            const float t = (pq.x * s.y - pq.y * s.x) * inv_rxs;

            if( (t < 0.0f) || (t > 1.0f) )
                continue;

            const float u = ( pq.x * aSegRay.m_End_minus_start.y -
                              pq.y * aSegRay.m_End_minus_start.x ) * inv_rxs;

            if( (u < 0.0f) || (u > 1.0f) )
                continue;

            if( ( hitIndex == -1 ) || ( t <= tMin ) )
            {
                tMin = t;
                hitIndex = i;
                hitU = u;
            }
        }
    }

    if( hitIndex >= 0 )
    {
        wxASSERT( (tMin >= 0.0f) && (tMin <= 1.0f) );

        *aOutT = tMin;
        *aNormalOut = glm::normalize(
                            m_open_segments[hitIndex].m_Normals.m_Start * hitU +
                            m_open_segments[hitIndex].m_Normals.m_End *
                            (1.0f - hitU) );

        return true;
    }

    return false;
}


INTERSECTION_RESULT CPOLYGONBLOCK2D::IsBBoxInside( const CBBOX2D &aBBox ) const
{

    return INTERSECTION_RESULT::MISSES;
}


bool CPOLYGONBLOCK2D::IsPointInside( const SFVEC2F &aPoint ) const
{
    // NOTE: we could add here a test for the bounding box, but because in the
    // 3d object it already checked for a 3d bbox.

    // First test if point is inside a hole.
    // If true it can early exit
    for( unsigned int i = 0; i < m_outers_and_holes.m_Holes.size(); i++ )
        if( !m_outers_and_holes.m_Holes[i].empty() )
            if( polygon_IsPointInside( m_outers_and_holes.m_Holes[i], aPoint ) )
                return false;

    // At this moment, the point is not inside a hole, so check if it is
    // inside the polygon
    for( unsigned int i = 0; i < m_outers_and_holes.m_Outers.size(); i++ )
        if( !m_outers_and_holes.m_Outers.empty() )
            if( polygon_IsPointInside( m_outers_and_holes.m_Outers[i], aPoint ) )
                return true;

    // Miss the polygon
    return false;
}


// CDUMMYBLOCK2D
// /////////////////////////////////////////////////////////////////////////////

CDUMMYBLOCK2D::CDUMMYBLOCK2D(
        const SFVEC2F& aPbMin, const SFVEC2F& aPbMax, const BOARD_ITEM& aBoardItem )
        : COBJECT2D( OBJECT2D_TYPE::DUMMYBLOCK, aBoardItem )
{
    m_bbox.Set( aPbMin, aPbMax );
    m_bbox.ScaleNextUp();
    m_centroid = m_bbox.GetCenter();
}


CDUMMYBLOCK2D::CDUMMYBLOCK2D( const CBBOX2D& aBBox, const BOARD_ITEM& aBoardItem )
        : COBJECT2D( OBJECT2D_TYPE::DUMMYBLOCK, aBoardItem )
{
    m_bbox.Set( aBBox );
    m_bbox.ScaleNextUp();
    m_centroid = m_bbox.GetCenter();
}


bool CDUMMYBLOCK2D::Intersects( const CBBOX2D &aBBox ) const
{
    return m_bbox.Intersects( aBBox );
}


bool CDUMMYBLOCK2D::Overlaps( const CBBOX2D &aBBox ) const
{
    // Not implemented
    return false;
}


bool CDUMMYBLOCK2D::Intersect( const RAYSEG2D &aSegRay,
                               float *aOutT,
                               SFVEC2F *aNormalOut ) const
{
    // The dummy block will be never intersected because it have no edges,
    // only it have a plan surface of the size of the bounding box
    return false;
}


INTERSECTION_RESULT CDUMMYBLOCK2D::IsBBoxInside( const CBBOX2D &aBBox ) const
{
    //!TODO:
    return INTERSECTION_RESULT::MISSES;
}


bool CDUMMYBLOCK2D::IsPointInside( const SFVEC2F &aPoint ) const
{
    // The dummy is filled in all his bounding box, so if it hit the bbox
    // it will hit this dummy
    if( m_bbox.Inside( aPoint ) )
        return true;

    return false;
}


// Polygon process and conversion
// ////////////////////////////////////////////////////////////////////////////

typedef std::vector<SFVEC2F> KF_POINTS;

#define MAX_NR_DIVISIONS 96


static bool intersect( const SEGMENT_WITH_NORMALS &aSeg,
                       const SFVEC2F &aStart,
                       const SFVEC2F &aEnd )
{
    const SFVEC2F r = aEnd - aStart;
    const SFVEC2F s = aSeg.m_Precalc_slope;
    const SFVEC2F q = aSeg.m_Start;

    const float rxs = r.x * s.y - r.y * s.x;

    if( fabs(rxs) >  glm::epsilon<float>() )
    {
        const float inv_rxs = 1.0f / rxs;

        const SFVEC2F pq = q - aStart;

        const float t = (pq.x * s.y - pq.y * s.x) * inv_rxs;

        if( (t < 0.0f) || (t > 1.0f) )
            return false;

        const float u = (pq.x * r.y - pq.y * r.x) * inv_rxs;

        if( (u < 0.0f) || (u > 1.0f) )
            return false;

        return true;
    }

    return false;
}


static void extractPathsFrom( const SEGMENTS_WIDTH_NORMALS &aSegList,
                              const CBBOX2D &aBBox,
                              SEGMENTS_WIDTH_NORMALS &aOutSegThatIntersect )
{
    wxASSERT( aSegList.size () >= 3 );

    unsigned int i;
    unsigned int j = aSegList.size() - 1;

    const SFVEC2F p1( aBBox.Min().x, aBBox.Min().y );
    const SFVEC2F p2( aBBox.Max().x, aBBox.Min().y );
    const SFVEC2F p3( aBBox.Max().x, aBBox.Max().y );
    const SFVEC2F p4( aBBox.Min().x, aBBox.Max().y );

    aOutSegThatIntersect.clear();

    for( i = 0; i < aSegList.size(); j = i++ )
    {
        if( aBBox.Inside( aSegList[i].m_Start ) ||
            aBBox.Inside( aSegList[j].m_Start ) )
        {
            // if the segment points are inside the bounding box then this
            // segment is touching the bbox.
            aOutSegThatIntersect.push_back( aSegList[i] );
        }
        else
        {
            // Check if a segment intersects the bounding box

            // Make a bounding box based on the segments start and end
            CBBOX2D segmentBBox( aSegList[i].m_Start,
                                 aSegList[j].m_Start );

            if( aBBox.Intersects( segmentBBox ) )
            {

                const SEGMENT_WITH_NORMALS &seg = aSegList[i];

                if( intersect( seg, p1, p2 ) ||
                    intersect( seg, p2, p3 ) ||
                    intersect( seg, p3, p4 ) ||
                    intersect( seg, p4, p1 ) )
                {
                    aOutSegThatIntersect.push_back( seg );
                }
            }
        }
    }
}


static void polygon_Convert( const SHAPE_LINE_CHAIN &aPath,
                             SEGMENTS &aOutSegment,
                             float aBiuTo3DunitsScale )
{
    aOutSegment.resize( aPath.PointCount() );

    for( int j = 0; j < aPath.PointCount(); j++ )
    {
        const VECTOR2I &a = aPath.CPoint( j );

        aOutSegment[j].m_Start = SFVEC2F( (float) a.x * aBiuTo3DunitsScale,
                                          (float)-a.y * aBiuTo3DunitsScale );
    }

    unsigned int i;
    unsigned int j = aOutSegment.size () - 1;

    for( i = 0; i < aOutSegment.size (); j = i++ )
    {
        // Calculate constants for each segment
        aOutSegment[i].m_inv_JY_minus_IY = 1.0f / ( aOutSegment[j].m_Start.y -
                                                    aOutSegment[i].m_Start.y );

        aOutSegment[i].m_JX_minus_IX = (aOutSegment[j].m_Start.x -
                                        aOutSegment[i].m_Start.x);
    }
}


void Convert_path_polygon_to_polygon_blocks_and_dummy_blocks(
        const SHAPE_POLY_SET &aMainPath,
        CGENERICCONTAINER2D &aDstContainer,
        float aBiuTo3DunitsScale,
        float aDivFactor,
        const BOARD_ITEM &aBoardItem,
        int aPolyIndex )
{
    // Get the path

    wxASSERT( aPolyIndex < aMainPath.OutlineCount() );

    const SHAPE_LINE_CHAIN& path = aMainPath.COutline( aPolyIndex );

    BOX2I pathBounds = path.BBox();

    // Convert the points to segments class
    CBBOX2D bbox;
    bbox.Reset();

    // Contains the main list of segments and each segment normal interpolated
    SEGMENTS_WIDTH_NORMALS segments_and_normals;

    // Contains a closed polygon used to calc if points are inside
    SEGMENTS segments;

    segments_and_normals.reserve( path.PointCount() );
    segments.reserve( path.PointCount() );

    SFVEC2F prevPoint;

    for( int i = 0; i < path.PointCount(); i++ )
    {
        const VECTOR2I& a = path.CPoint( i );

        const SFVEC2F point ( (float)( a.x) * aBiuTo3DunitsScale,
                              (float)(-a.y) * aBiuTo3DunitsScale );

        // Only add points that are not coincident
        if( (i == 0) ||
            (fabs(prevPoint.x - point.x) > FLT_EPSILON) ||
            (fabs(prevPoint.y - point.y) > FLT_EPSILON) )
        {
            prevPoint = point;

            bbox.Union( point );

            SEGMENT_WITH_NORMALS sn;
            sn.m_Start = point;
            segments_and_normals.push_back( sn );

            POLYSEGMENT ps;
            ps.m_Start = point;
            segments.push_back( ps );
        }
    }

    bbox.ScaleNextUp();


    // Calc the slopes, normals and some statistics about this polygon
    unsigned int i;
    unsigned int j = segments_and_normals.size() - 1;

    // Temporary normal to the segment, it will later be used for interpolation
    std::vector< SFVEC2F >  tmpSegmentNormals;
    tmpSegmentNormals.resize( segments_and_normals.size() );

    float medOfTheSquaresSegmentLength = 0.0f;
#ifdef PRINT_STATISTICS_3D_VIEWER
    float minLength = FLT_MAX;
#endif

    for( i = 0; i < segments_and_normals.size(); j = i++ )
    {
        const SFVEC2F slope = segments_and_normals[j].m_Start -
                              segments_and_normals[i].m_Start;

        segments_and_normals[i].m_Precalc_slope = slope;

        // Calculate constants for each segment
        segments[i].m_inv_JY_minus_IY = 1.0f / ( segments_and_normals[j].m_Start.y -
                                                 segments_and_normals[i].m_Start.y );

        segments[i].m_JX_minus_IX = ( segments_and_normals[j].m_Start.x -
                                      segments_and_normals[i].m_Start.x );

        // The normal orientation expect a fixed polygon orientation (!TODO: which one?)
        //tmpSegmentNormals[i] = glm::normalize( SFVEC2F( -slope.y, +slope.x ) );
        tmpSegmentNormals[i] = glm::normalize( SFVEC2F( slope.y, -slope.x ) );

        const float length = slope.x * slope.x + slope.y * slope.y;

#ifdef PRINT_STATISTICS_3D_VIEWER
        if( length < minLength )
            minLength = length;
#endif

        medOfTheSquaresSegmentLength += length;
    }

#ifdef PRINT_STATISTICS_3D_VIEWER
    float minSegmentLength = sqrt( minLength );
#endif

    // This calc an approximation of medium lengths, that will be used to calc
    // the size of the division.
    medOfTheSquaresSegmentLength /= segments_and_normals.size();
    medOfTheSquaresSegmentLength = sqrt( medOfTheSquaresSegmentLength );


    // Compute the normal interpolation
    // If calculate the dot between the segments, if they are above/below some
    // threshould it will not interpolated it (ex: if you are in a edge corner
    // or in a smooth transaction)
    j = segments_and_normals.size() - 1;
    for( i = 0; i < segments_and_normals.size(); j = i++ )
    {
        const SFVEC2F normalBeforeSeg = tmpSegmentNormals[j];
        const SFVEC2F normalSeg       = tmpSegmentNormals[i];
        const SFVEC2F normalAfterSeg  = tmpSegmentNormals[ (i + 1) %
                                                           segments_and_normals.size() ];

        const float dotBefore = glm::dot( normalBeforeSeg, normalSeg );
        const float dotAfter  = glm::dot( normalAfterSeg,  normalSeg );

        if( dotBefore < 0.7f )
            segments_and_normals[i].m_Normals.m_Start = normalSeg;
        else
            segments_and_normals[i].m_Normals.m_Start =
                glm::normalize( (normalBeforeSeg * dotBefore ) + normalSeg );

        if( dotAfter < 0.7f )
            segments_and_normals[i].m_Normals.m_End = normalSeg;
        else
            segments_and_normals[i].m_Normals.m_End =
                glm::normalize( (normalAfterSeg * dotAfter ) + normalSeg );
    }

    if( aDivFactor == 0.0f )
        aDivFactor = medOfTheSquaresSegmentLength;

    SFVEC2UI grid_divisions;
    grid_divisions.x = (unsigned int)( (bbox.GetExtent().x / aDivFactor) );
    grid_divisions.y = (unsigned int)( (bbox.GetExtent().y / aDivFactor) );

    grid_divisions = glm::clamp( grid_divisions ,
                                 SFVEC2UI( 1, 1 ),
                                 SFVEC2UI( MAX_NR_DIVISIONS, MAX_NR_DIVISIONS ) );

    // Calculate the steps advance of the grid
    SFVEC2F blockAdvance;

    blockAdvance.x = bbox.GetExtent().x / (float)grid_divisions.x;
    blockAdvance.y = bbox.GetExtent().y / (float)grid_divisions.y;

    wxASSERT( blockAdvance.x > 0.0f );
    wxASSERT( blockAdvance.y > 0.0f );

    const int leftToRight_inc = (pathBounds.GetRight()  - pathBounds.GetLeft()) /
                                grid_divisions.x;

    const int topToBottom_inc = (pathBounds.GetBottom() - pathBounds.GetTop())  /
                                grid_divisions.y;

    // Statistics
    unsigned int stats_n_empty_blocks = 0;
    unsigned int stats_n_dummy_blocks = 0;
    unsigned int stats_n_poly_blocks = 0;
    unsigned int stats_sum_size_of_polygons = 0;


    // Step by each block of a grid trying to extract segments and create
    // polygon blocks

    int topToBottom = pathBounds.GetTop();
    float blockY = bbox.Max().y;

    for( unsigned int iy = 0; iy < grid_divisions.y; iy++ )
    {

        int leftToRight = pathBounds.GetLeft();
        float blockX = bbox.Min().x;

        for( unsigned int ix = 0; ix < grid_divisions.x; ix++ )
        {
            CBBOX2D blockBox( SFVEC2F( blockX,
                                       blockY - blockAdvance.y ),
                              SFVEC2F( blockX + blockAdvance.x,
                                       blockY                  ) );

            // Make the box large to it will catch (intersect) the edges
            blockBox.ScaleNextUp();
            blockBox.ScaleNextUp();
            blockBox.ScaleNextUp();

            SEGMENTS_WIDTH_NORMALS extractedSegments;

            extractPathsFrom( segments_and_normals, blockBox, extractedSegments );


            if( extractedSegments.empty() )
            {

                SFVEC2F p1( blockBox.Min().x, blockBox.Min().y );
                SFVEC2F p2( blockBox.Max().x, blockBox.Min().y );
                SFVEC2F p3( blockBox.Max().x, blockBox.Max().y );
                SFVEC2F p4( blockBox.Min().x, blockBox.Max().y );

                if( polygon_IsPointInside( segments, p1 ) ||
                    polygon_IsPointInside( segments, p2 ) ||
                    polygon_IsPointInside( segments, p3 ) ||
                    polygon_IsPointInside( segments, p4 ) )
                {
                    // In this case, the segments are not intersecting the
                    // polygon, so it means that if any point is inside it,
                    // then all other are inside the polygon.
                    // This is a full bbox inside, so add a dummy box

                    aDstContainer.Add( new CDUMMYBLOCK2D( blockBox, aBoardItem ) );
                    stats_n_dummy_blocks++;
                }
                else
                {
                    // Points are outside, so this block complety missed the polygon
                    // In this case, no objects need to be added
                    stats_n_empty_blocks++;
                }
            }
            else
            {
                // At this point, the borders of polygon were intersected by the
                // bounding box, so we must calculate a new polygon that will
                // close that small block.
                // This block will be used to calculate if points are inside
                // the (sub block) polygon.

                SHAPE_POLY_SET subBlockPoly;

                SHAPE_LINE_CHAIN sb = SHAPE_LINE_CHAIN( { VECTOR2I( leftToRight, topToBottom ),
                        VECTOR2I( leftToRight + leftToRight_inc, topToBottom ),
                        VECTOR2I( leftToRight + leftToRight_inc, topToBottom + topToBottom_inc ),
                        VECTOR2I( leftToRight, topToBottom + topToBottom_inc ) } );

                //sb.Append( leftToRight, topToBottom );
                sb.SetClosed( true );

                subBlockPoly.AddOutline( sb );

                // We need here a strictly simple polygon with outlines and holes
                SHAPE_POLY_SET solution;
                solution.BooleanIntersection( aMainPath,
                                              subBlockPoly,
                                              SHAPE_POLY_SET::PM_STRICTLY_SIMPLE );

                OUTERS_AND_HOLES outersAndHoles;

                outersAndHoles.m_Holes.clear();
                outersAndHoles.m_Outers.clear();

                for( int idx = 0; idx < solution.OutlineCount(); idx++ )
                {
                    const SHAPE_LINE_CHAIN & outline = solution.Outline( idx );

                    SEGMENTS solutionSegment;

                    polygon_Convert( outline, solutionSegment, aBiuTo3DunitsScale );
                    outersAndHoles.m_Outers.push_back( solutionSegment );

                    stats_sum_size_of_polygons += solutionSegment.size();

                    for( int holeIdx = 0;
                         holeIdx < solution.HoleCount( idx );
                         holeIdx++ )
                    {
                        const SHAPE_LINE_CHAIN & hole = solution.Hole( idx, holeIdx );

                        polygon_Convert( hole, solutionSegment, aBiuTo3DunitsScale );
                        outersAndHoles.m_Holes.push_back( solutionSegment );
                        stats_sum_size_of_polygons += solutionSegment.size();
                    }

                }

                if( !outersAndHoles.m_Outers.empty() )
                {
                    aDstContainer.Add( new CPOLYGONBLOCK2D( extractedSegments,
                                                            outersAndHoles,
                                                            aBoardItem ) );
                    stats_n_poly_blocks++;
                }
            }

            blockX += blockAdvance.x;
            leftToRight += leftToRight_inc;
        }

        blockY -= blockAdvance.y;
        topToBottom += topToBottom_inc;
    }

#ifdef PRINT_STATISTICS_3D_VIEWER
    printf( "////////////////////////////////////////////////////////////////////////////////\n" );
    printf( "Convert_path_polygon_to_polygon_blocks_and_dummy_blocks\n" );
    printf( "  grid_divisions (%u, %u)\n", grid_divisions.x, grid_divisions.y );
    printf( "  N Total Blocks %u\n", grid_divisions.x * grid_divisions.y );
    printf( "  N Empty Blocks %u\n", stats_n_empty_blocks );
    printf( "  N Dummy Blocks %u\n", stats_n_dummy_blocks );
    printf( "  N Polyg Blocks %u\n", stats_n_poly_blocks );
    printf( "  Med N Seg Poly %u\n", stats_sum_size_of_polygons / stats_n_poly_blocks );
    printf( "  medOfTheSquaresSegmentLength %f\n", medOfTheSquaresSegmentLength );
    printf( "  minSegmentLength             %f\n", minSegmentLength );
    printf( "  aDivFactor                   %f\n", aDivFactor );
    printf( "////////////////////////////////////////////////////////////////////////////////\n" );
#endif
}


#ifdef DEBUG
static void polygon_Convert( const ClipperLib::Path &aPath,
                             SEGMENTS &aOutSegment,
                             float aBiuTo3DunitsScale )
{
    aOutSegment.resize( aPath.size() );

    for( unsigned i = 0; i < aPath.size(); i++ )
    {
        aOutSegment[i].m_Start = SFVEC2F( (float) aPath[i].X * aBiuTo3DunitsScale,
                                          (float)-aPath[i].Y * aBiuTo3DunitsScale );
    }

    unsigned int i;
    unsigned int j = aOutSegment.size () - 1;

    for( i = 0; i < aOutSegment.size (); j = i++ )
    {
        // Calculate constants for each segment
        aOutSegment[i].m_inv_JY_minus_IY = 1.0f / ( aOutSegment[j].m_Start.y -
                                                    aOutSegment[i].m_Start.y );
        aOutSegment[i].m_JX_minus_IX = (aOutSegment[j].m_Start.x - aOutSegment[i].m_Start.x);
    }
}

void Polygon2d_TestModule()
{
    // "This structure contains a sequence of IntPoint vertices defining a
    // single contour"
    ClipperLib::Path aPath;

    SEGMENTS aSegments;

    aPath.resize( 4 );

    aPath[0] = ClipperLib::IntPoint( -2, -2 );
    aPath[1] = ClipperLib::IntPoint(  2, -2 );
    aPath[2] = ClipperLib::IntPoint(  2,  2 );
    aPath[3] = ClipperLib::IntPoint( -2,  2 );

    // It must be an outer polygon
    wxASSERT( ClipperLib::Orientation( aPath ) );

    polygon_Convert( aPath, aSegments, 1.0f );

    wxASSERT( aPath.size() == aSegments.size() );

    wxASSERT( aSegments[0].m_Start == SFVEC2F( -2.0f,  2.0f ) );
    wxASSERT( aSegments[1].m_Start == SFVEC2F(  2.0f,  2.0f ) );
    wxASSERT( aSegments[2].m_Start == SFVEC2F(  2.0f, -2.0f ) );
    wxASSERT( aSegments[3].m_Start == SFVEC2F( -2.0f, -2.0f ) );

    wxASSERT( polygon_IsPointInside( aSegments, SFVEC2F(  0.0f,  0.0f ) ) );
    wxASSERT( polygon_IsPointInside( aSegments, SFVEC2F( -1.9f, -1.9f ) ) );
    wxASSERT( polygon_IsPointInside( aSegments, SFVEC2F( -1.9f,  1.9f ) ) );
    wxASSERT( polygon_IsPointInside( aSegments, SFVEC2F(  1.9f,  1.9f ) ) );
    wxASSERT( polygon_IsPointInside( aSegments, SFVEC2F(  1.9f, -1.9f ) ) );

    wxASSERT( polygon_IsPointInside( aSegments, SFVEC2F( -2.1f, -2.0f ) ) == false );
    wxASSERT( polygon_IsPointInside( aSegments, SFVEC2F( -2.1f,  2.0f ) ) == false );
    wxASSERT( polygon_IsPointInside( aSegments, SFVEC2F(  2.1f,  2.0f ) ) == false );
    wxASSERT( polygon_IsPointInside( aSegments, SFVEC2F(  2.1f, -2.0f ) ) == false );
}
#endif