Hi Sanak,<br>Thanks a lot for the modified code: it worked on perfection!<br>Here is a screenshot of a run with my shapefile:<br><br><a href="http://ladybug.no-ip.org/files/inCircleFinal.png">http://ladybug.no-ip.org/files/inCircleFinal.png</a><br>
<br>        Have a good rest of the weekend!<br>                                                             Jo<br><br><div class="gmail_quote">2009/7/19  <span dir="ltr">&lt;<a href="mailto:geos-devel-request@lists.osgeo.org">geos-devel-request@lists.osgeo.org</a>&gt;</span><br>
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Today&#39;s Topics:<br>
<br>
   1. Re: Re: Computational Geometry Problem (Sanak Goe)<br>
<br>
<br>
----------------------------------------------------------------------<br>
<br>
Message: 1<br>
Date: Sun, 19 Jul 2009 21:24:34 +0900<br>
From: Sanak Goe &lt;<a href="mailto:geosanak@gmail.com">geosanak@gmail.com</a>&gt;<br>
Subject: Re: [geos-devel] Re: Computational Geometry Problem<br>
To: GEOS Development List &lt;<a href="mailto:geos-devel@lists.osgeo.org">geos-devel@lists.osgeo.org</a>&gt;<br>
Message-ID:<br>
        &lt;<a href="mailto:5f9be0a0907190524n5a8de434y38731cf04e7770d0@mail.gmail.com">5f9be0a0907190524n5a8de434y38731cf04e7770d0@mail.gmail.com</a>&gt;<br>
Content-Type: text/plain; charset=&quot;iso-8859-1&quot;<br>
<br>
Skipped content of type multipart/alternative-------------- next part --------------<br>
#include &lt;locale.h&gt;<br>
#include &lt;iostream&gt;<br>
#include &lt;vector&gt;<br>
#include &lt;algorithm&gt;<br>
#include &lt;stdexcept&gt;<br>
#include &lt;map&gt; // added by sanak 2009.07.19<br>
#ifdef _MSC_VER<br>
#include &lt;io.h&gt;<br>
#endif // _MSC_VER<br>
<br>
//Geos<br>
#include &lt;geos_c.h&gt;<br>
<br>
#include &lt;geos/algorithm/CGAlgorithms.h&gt;<br>
#include &lt;geos/algorithm/HCoordinate.h&gt;<br>
#include &lt;geos/geom/Coordinate.h&gt;<br>
#include &lt;geos/geom/CoordinateArraySequence.h&gt;<br>
#include &lt;geos/geom/LineString.h&gt;<br>
#include &lt;geos/geom/MultiPoint.h&gt;<br>
#include &lt;geos/geom/Point.h&gt;<br>
#include &lt;geos/geom/Polygon.h&gt;<br>
#include &lt;geos/io/WKTReader.h&gt;<br>
#include &lt;geos/io/WKTWriter.h&gt;<br>
<br>
// &lt;-- modified by sanak 2009.07.19<br>
//const double epsilonArea = 100.0;<br>
const double epsilonRadius = 0.1;<br>
// --&gt; modified by sanak 2009.07.19<br>
<br>
// &lt;-- Boost code<br>
template &lt; class BidirectionalIterator &gt;<br>
bool next_combination ( BidirectionalIterator first1 ,<br>
  BidirectionalIterator last1 ,<br>
  BidirectionalIterator first2 ,<br>
  BidirectionalIterator last2 )<br>
{<br>
  if (( first1 == last1 ) || ( first2 == last2 )) {<br>
    return false ;<br>
  }<br>
  BidirectionalIterator m1 = last1 ;<br>
  BidirectionalIterator m2 = last2 ; --m2;<br>
  while (--m1 != first1 &amp;&amp; !(* m1 &lt; *m2 )){<br>
  }<br>
  bool result = (m1 == first1 ) &amp;&amp; !(* first1 &lt; *m2 );<br>
  if (! result ) {<br>
    while ( first2 != m2 &amp;&amp; !(* m1 &lt; * first2 )) {<br>
      ++ first2 ;<br>
    }<br>
    first1 = m1;<br>
    std :: iter_swap (first1 , first2 );<br>
    ++ first1 ;<br>
    ++ first2 ;<br>
  }<br>
  if (( first1 != last1 ) &amp;&amp; ( first2 != last2 )) {<br>
    m1 = last1 ; m2 = first2 ;<br>
    while (( m1 != first1 ) &amp;&amp; (m2 != last2 )) {<br>
      std :: iter_swap (--m1 , m2 );<br>
      ++ m2;<br>
    }<br>
    std :: reverse (first1 , m1 );<br>
    std :: reverse (first1 , last1 );<br>
    std :: reverse (m2 , last2 );<br>
    std :: reverse (first2 , last2 );<br>
  }<br>
  return ! result ;<br>
}<br>
<br>
template &lt; class BidirectionalIterator &gt;<br>
bool next_combination ( BidirectionalIterator first ,<br>
  BidirectionalIterator middle ,<br>
  BidirectionalIterator last )<br>
{<br>
  return next_combination (first , middle , middle , last );<br>
}<br>
// Boost Code --&gt;<br>
<br>
bool computeIncircle(<br>
                                         const geos::geom::Polygon* poly,<br>
                                         const geos::geom::Polygon* negbuf,<br>
                                         geos::geom::Coordinate&amp; center,<br>
                                         double&amp; radius)<br>
{<br>
        radius = 0.0;<br>
<br>
        if (negbuf == NULL)<br>
        {<br>
                negbuf = poly;<br>
        }<br>
<br>
        try<br>
        {<br>
<br>
                if (!negbuf-&gt;isValid())<br>
                {<br>
                        throw std::runtime_error(&quot;Invalid polygon.&quot;);<br>
                }<br>
<br>
                if (negbuf-&gt;getNumInteriorRing() &gt; 0)<br>
                {<br>
                        throw std::runtime_error(&quot;This sample only supports non-holes polygon.&quot;);<br>
                }<br>
<br>
                const geos::geom::LineString* shell = negbuf-&gt;getExteriorRing();<br>
                geos::geom::CoordinateArraySequence* coords = static_cast&lt;geos::geom::CoordinateArraySequence*&gt;(shell-&gt;getCoordinates());<br>
<br>
                // compute orientation of ring<br>
                if (!geos::algorithm::CGAlgorithms::isCCW(coords))<br>
                {<br>
                        coords-&gt;reverse(coords);<br>
                }<br>
<br>
                // compute angle bisector of every  continuous three points in polygon<br>
                size_t cnt = coords-&gt;size() - 1;<br>
                // &lt;-- modified by sanak 2009.07.19<br>
                //std::vector&lt;geos::algorithm::HCoordinate*&gt; bisects;<br>
                std::vector&lt;size_t&gt; bisectids;<br>
                std::map&lt;size_t, geos::algorithm::HCoordinate*&gt; bisects;<br>
                // --&gt; modified by sanak 2009.07.19<br>
                for (size_t i = 0; i &lt; cnt; i++)<br>
                {<br>
                        size_t prev = (i == 0) ? cnt - 1 : i - 1;<br>
                        size_t curr = i;<br>
                        size_t next = (i == cnt - 1) ? 0 : i + 1;<br>
<br>
                        // &lt;-- JTS 1.10 Code<br>
                        geos::geom::Coordinate a = coords-&gt;getAt(prev);<br>
                        geos::geom::Coordinate b = coords-&gt;getAt(curr);<br>
                        geos::geom::Coordinate c = coords-&gt;getAt(next);<br>
<br>
                        double len0 = b.distance(a);<br>
                        double len2 = b.distance(c);<br>
                        double frac = len0 / (len0 + len2);<br>
                        double dx = c.x - a.x;<br>
                        double dy = c.y - a.y;<br>
<br>
                        geos::geom::Coordinate splitPt = geos::geom::Coordinate(a.x + frac * dx, a.y + frac * dy);<br>
                        // --&gt; JTS 1.10 Code<br>
                        // &lt;-- modified by sanak 2009.07.19<br>
                        //bisects.push_back(new geos::algorithm::HCoordinate(b, splitPt));<br>
                        bisectids.push_back(i);<br>
                        bisects.insert(std::pair&lt;size_t, geos::algorithm::HCoordinate*&gt;(i, new geos::algorithm::HCoordinate(b, splitPt)));<br>
                        // --&gt; modified by sanak 2009.07.19<br>
                }<br>
<br>
                // get intersection points of angle bisectors<br>
                geos::geom::CoordinateArraySequence intsects;<br>
                do<br>
                {<br>
                        // &lt;-- modified by sanak 2009.07.19<br>
                        //geos::algorithm::HCoordinate* hc0 = bisects[0];<br>
                        //geos::algorithm::HCoordinate* hc1 = bisects[1];<br>
                        geos::algorithm::HCoordinate* hc0 = bisects[bisectids[0]];<br>
                        geos::algorithm::HCoordinate* hc1 = bisects[bisectids[1]];<br>
                        // --&gt; modified by sanak 2009.07.19<br>
                        geos::algorithm::HCoordinate* hcoord = new geos::algorithm::HCoordinate(*hc0, *hc1);<br>
                        try<br>
                        {<br>
                                // get intersection<br>
                                geos::geom::Coordinate coord = geos::geom::Coordinate(hcoord-&gt;getX(), hcoord-&gt;getY());<br>
<br>
                                // TODO:remove duplicate point<br>
                                intsects.add(coord);<br>
                        }<br>
                        catch (std::exception&amp; ex)<br>
                        {<br>
                                // no intersection<br>
                        }<br>
                        if (hcoord)<br>
                        {<br>
                                delete hcoord;<br>
                        }<br>
                }<br>
                // &lt;-- modified by sanak 2009.07.19<br>
                //while (next_combination(bisects.begin(), bisects.begin() + 2, bisects.end()));<br>
                while (next_combination(bisectids.begin(), bisectids.begin() + 2, bisectids.end()));<br>
                // --&gt; modified by sanak 2009.07.19<br>
<br>
                // clean up<br>
                if (bisects.size() &gt; 0)<br>
                {<br>
                        std::cout &lt;&lt; &quot;bissects ok.&quot; &lt;&lt; std::endl;<br>
                        // &lt;-- modified by sanak 2009.07.19<br>
                        //std::vector&lt;geos::algorithm::HCoordinate*&gt;::iterator it;<br>
                        //for (it = bisects.begin(); it != bisects.end(); it++)<br>
                        //{<br>
                        //      delete *it;<br>
                        //}<br>
                        std::map&lt;size_t, geos::algorithm::HCoordinate*&gt;::iterator it;<br>
                        for (it = bisects.begin(); it != bisects.end(); it++)<br>
                        {<br>
                                delete it-&gt;second;<br>
                        }<br>
                        // --&gt; modified by sanak 2009.07.19<br>
                }<br>
                else<br>
                std::cout &lt;&lt; &quot;No bissects.&quot; &lt;&lt; std::endl;<br>
<br>
                std::cout &lt;&lt; &quot;intsects.size()&quot; &lt;&lt; intsects.size() &lt;&lt;  std::endl;<br>
                if (intsects.size() &gt; 0)<br>
                {<br>
                        std::cout &lt;&lt; &quot;intsects ok.&quot; &lt;&lt; std::endl;<br>
<br>
                        geos::geom::Point* incenter = NULL;<br>
<br>
                        geos::geom::GeometryFactory factory;<br>
                        const geos::geom::LineString* line = poly-&gt;getExteriorRing();<br>
                        //geos::geom::MultiPoint* rcpoints = factory.createMultiPoint(intsects); // for debug<br>
<br>
                        std::vector&lt;geos::geom::Coordinate*&gt;::iterator it;<br>
                        for (size_t i = 0; i &lt; intsects.size(); i++)<br>
                        {<br>
                                geos::geom::Coordinate coord = intsects[i];<br>
                                // exclude points that are outer of polygon<br>
                                if (geos::algorithm::CGAlgorithms::isPointInRing(coord, coords))<br>
                                {<br>
                                        geos::geom::Point* point = factory.createPoint(coord);<br>
                                        // compute distance from every candidates of centres to polygon, and choose largest one<br>
                                        double distance = line-&gt;distance(point);<br>
                                        if (radius &lt; distance)<br>
                                        {<br>
                                                radius = distance;<br>
                                                incenter = point;<br>
                                        }<br>
                                }<br>
                                //else std::cout &lt;&lt; &quot;Point not in Ring.&quot; &lt;&lt; std::endl;<br>
                        }<br>
<br>
                        if (incenter != NULL &amp;&amp; radius != 0.0)<br>
                        {<br>
                                        geos::io::WKTWriter writer;<br>
                                        std::cout &lt;&lt; &quot;wkt : &quot; &lt;&lt; writer.write(incenter) &lt;&lt; std::endl;<br>
                                        std::cout &lt;&lt; &quot;radius : &quot; &lt;&lt; radius &lt;&lt; std::endl;<br>
<br>
                                center.x = incenter-&gt;getX();<br>
                                center.y = incenter-&gt;getY();<br>
                                //return true; // deleted by sanak 2009.07.19<br>
                        }<br>
                        // &lt;-- added by sanak 2009.07.19<br>
                        else<br>
                        {<br>
                                geos::geom::Point* intPt = negbuf-&gt;getInteriorPoint();<br>
                                center.x = intPt-&gt;getX();<br>
                                center.y = intPt-&gt;getY();<br>
                                radius = line-&gt;distance(intPt);<br>
                        }<br>
                        return true;<br>
                        // --&gt; added by sanak 2009.07.19<br>
                }<br>
                else<br>
                {<br>
                        std::cout &lt;&lt; &quot;No intsects.&quot; &lt;&lt; std::endl;<br>
                        throw std::runtime_error(&quot;Couldn&#39;t get incenter.&quot;);<br>
                }<br>
        }<br>
        catch (std::exception&amp; ex)<br>
        {<br>
                std::cerr &lt;&lt; &quot;Exception : &quot; &lt;&lt; ex.what() &lt;&lt; std::endl;<br>
                throw ex;<br>
                return false;<br>
        }<br>
        return false;<br>
}<br>
<br>
int main(int argc, char* argv[])<br>
{<br>
        // check stdin<br>
#ifdef _MSC_VER<br>
        if (::_isatty(fileno(stdin)))<br>
#else<br>
        if (::isatty(fileno(stdin)))<br>
#endif // _MSC_VER<br>
        {<br>
                std::cerr &lt;&lt; &quot;Usage: %s &lt; [wktfile(polygon)]&quot; &lt;&lt; std::endl;<br>
                return -1;<br>
        }<br>
<br>
        std::string line;<br>
        geos::io::WKTReader reader;<br>
        std::vector&lt;geos::geom::Polygon*&gt; g;<br>
        while (getline(std::cin, line, &#39;\n&#39;))<br>
        {<br>
                //std::cout &lt;&lt; line &lt;&lt; std::endl;<br>
                geos::geom::Polygon* geom =<br>
                static_cast&lt;geos::geom::Polygon*&gt;(reader.read(line));<br>
<br>
                if (geom == NULL &amp;&amp; geom-&gt;getGeometryType() != &quot;Polygon&quot;)<br>
                {<br>
                        throw std::runtime_error(&quot;This sample only supports polygon geometry&quot;);<br>
                }<br>
<br>
                geos::geom::Polygon* poly = static_cast&lt;geos::geom::Polygon*&gt;(geom);<br>
                if (!poly-&gt;isValid())<br>
                {<br>
                        throw std::runtime_error(&quot;Invalid polygon.&quot;);<br>
                }<br>
<br>
                if (poly-&gt;getNumInteriorRing() &gt; 0)<br>
                {<br>
                        throw std::runtime_error(&quot;This sample only supports non-holes polygon.&quot;);<br>
                }<br>
<br>
                g.push_back(poly);<br>
        }<br>
<br>
<br>
        try<br>
        {<br>
<br>
                for (int i=0 ; i &lt; g.size(); ++i)<br>
                {<br>
                        geos::geom::Polygon* negbuf = NULL;<br>
                        double prevRadius = 0.0; // added by sanak 2009.07.19<br>
                        while (true)<br>
                        {<br>
                                geos::geom::Coordinate center;<br>
                                double radius = 0.0;<br>
                                if (computeIncircle(g[i], negbuf, center, radius))<br>
                                {<br>
                                        // &lt;-- modified by sanak 2009.07.19<br>
                                        //negbuf = static_cast&lt;geos::geom::Polygon*&gt;(g[i]-&gt;buffer(-radius));<br>
                                        //if (negbuf == NULL &amp;&amp; negbuf-&gt;getGeometryType() != &quot;Polygon&quot;)<br>
                                        //{<br>
                                        //      // TODO:<br>
                                        //      throw std::runtime_error(&quot;Intercepted!!!!!!!&quot;);<br>
                                        //}<br>
                                        //double area = negbuf-&gt;getArea();<br>
<br>
                                        //if (area &lt; epsilonArea)<br>
                                        geos::geom::Geometry* buf = g[i]-&gt;buffer(-(radius));<br>
                                        std::string buftype = buf-&gt;getGeometryType();<br>
                                        if (buftype == &quot;Polygon&quot;)<br>
                                        {<br>
                                                negbuf = static_cast&lt;geos::geom::Polygon*&gt;(buf);<br>
                                        }<br>
                                        else if (buftype == &quot;MultiPolygon&quot;)<br>
                                        {<br>
                                                size_t cnt = buf-&gt;getNumGeometries();<br>
                                                double maxradius = 0.0;<br>
                                                double tmpradius = 0.0;<br>
                                                geos::geom::Coordinate tmpcenter;<br>
                                                for (size_t j = 0; j &lt; cnt; j++)<br>
                                                {<br>
                                                        const geos::geom::Polygon* item = static_cast&lt;const geos::geom::Polygon*&gt;(buf-&gt;getGeometryN(j));<br>
                                                        if (computeIncircle(g[i], item, tmpcenter, tmpradius))<br>
                                                        {<br>
                                                                if (tmpradius &gt; maxradius)<br>
                                                                {<br>
                                                                        negbuf = static_cast&lt;geos::geom::Polygon*&gt;(item-&gt;clone());<br>
                                                                        center = tmpcenter;<br>
                                                                        radius = tmpradius;<br>
                                                                        maxradius = tmpradius;<br>
                                                                }<br>
                                                        }<br>
                                                }<br>
                                        }<br>
<br>
                                        if ((radius - prevRadius) &lt; epsilonRadius)<br>
                                        // --&gt; modified by sanak 2009.07.19<br>
                                        {<br>
<br>
                                                std::cout &lt;&lt; &quot;center : &quot; &lt;&lt; center.toString() &lt;&lt; std::endl;<br>
                                                std::cout &lt;&lt; &quot;radius : &quot; &lt;&lt; radius &lt;&lt; std::endl;<br>
                                                geos::geom::GeometryFactory factory;<br>
                                                geos::geom::Point* centerPt = factory.createPoint(center);<br>
                                                geos::geom::Geometry* incircle = centerPt-&gt;buffer(radius);<br>
                                                geos::io::WKTWriter writer;<br>
                                                std::cout &lt;&lt; &quot;wkt : &quot; &lt;&lt; writer.write(incircle) &lt;&lt; std::endl;<br>
                                                // &lt;-- modified by sanak 2009.07.19<br>
                                                //return 0;<br>
                                                break;<br>
                                                // --&gt; modified by sanak 2009.07.19<br>
                                        }<br>
                                        prevRadius = radius; // added by sanak 2009.07.19<br>
                                }<br>
                                else<br>
                                {<br>
                                        std::cout &lt;&lt; &quot;Could not compute!&quot; &lt;&lt; std::endl;<br>
                                        return -2;<br>
                                }<br>
                        }<br>
                }<br>
        }<br>
        catch (std::exception&amp; ex)<br>
        {<br>
                std::cerr &lt;&lt; &quot;Exception : &quot; &lt;&lt; ex.what() &lt;&lt; std::endl;<br>
                return -3;<br>
        }<br>
<br>
        return 0;<br>
}<br>
<br>
------------------------------<br>
<br>
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<br>
End of geos-devel Digest, Vol 81, Issue 13<br>
******************************************<br>
</blockquote></div><br><br clear="all"><br>-- <br>&quot;#define QUESTION ((bb) || !(bb))&quot;  (Shakespeare)<br><br>