BOOL BCGPCalculateIntersectPoint(const CBCGPPointsArray& arPoly1, const CBCGPPointsArray& arPoly2,
CBCGPPoint& ptIntersect)
{
int nPoly1Size = (int)arPoly1.GetSize();
int nPoly2Size = (int)arPoly2.GetSize();
if (nPoly1Size == 0 || nPoly2Size == 0)
{
return FALSE;
}
const CBCGPPoint* pData1 = arPoly1.GetData ();
const CBCGPPoint* pData2 = arPoly2.GetData ();
CBCGPPointsArray arPolyRes;
arPolyRes.SetSize (0, nPoly1Size + nPoly2Size);
int i = 0;
int j = 0;
// 1. find all points from arPoly1F in arPoly2F
int nSize1 = 0;
for (i = 0; i < nPoly1Size; i++)
{
const CBCGPPoint& pt = pData1[i];
if (PointInPolygon (arPoly2, pt))
{
if (AddPointInPolygon(arPolyRes, pt))
{
nSize1++;
}
}
}
// all points in arPoly2F
if (nSize1 != nPoly1Size)
{
// 2. find all points from arPoly2F in arPoly1F
int nSize2 = 0;
for (i = 0; i < nPoly2Size; i++)
{
const CBCGPPoint& pt = pData2[i];
if (PointInPolygon (arPoly1, pt))
{
if (AddPointInPolygon(arPolyRes, pt))
{
nSize2++;
}
}
}
// all points in arPoly1F
if (nSize1 != 0 || nSize2 != nPoly2Size)
{
// 3. find all intersection points arPoly1F and arPoly2F
for (i = 0; i < nPoly1Size; i++)
{
const CBCGPPoint& ptStart1 = pData1[i];
const CBCGPPoint& ptEnd1 = pData1[(i + 1) % nPoly1Size];
for (j = 0; j < nPoly2Size; j++)
{
const CBCGPPoint& ptStart2 = pData2[j];
const CBCGPPoint& ptEnd2 = pData2[(j + 1) % nPoly2Size];
if (bcgp_classify_point2D(ptStart1, ptEnd1, ptStart2) !=
bcgp_classify_point2D(ptStart1, ptEnd1, ptEnd2))
{
CBCGPPoint pt;
if (BCGPIntersectPoints2D (ptStart1, ptEnd1, ptStart2, ptEnd2, pt))
{
AddPointInPolygon(arPolyRes, pt);
}
}
}
}
}
}
int nSize = (int)arPolyRes.GetSize();
if (nSize < 2)
{
return FALSE;
}
ptIntersect.x = 0.0;
ptIntersect.y = 0.0;
for (i = 0; i < nSize; i++)
{
ptIntersect += arPolyRes[i];
}
ptIntersect /= nSize;
return TRUE;
}
