You need to use the AcDbMPolygon Class;
Also, you can use this url link to view the whole topic about how to
implement AcDbMPolygon for your case, including the help from the master
Alexander Rivilis.
http://www.theswamp.org/index.php?topic=9145.0
I went into that route some time ago, here is one function to find if one
poly is inside another poly:
static void LESQsomefunctions_PINP(void)
{
ads_name en;
AcGePoint3d p;
Acad::ErrorStatus es;
AcDbObjectId objId1, objId2;
AcDbCurve *pEnt = NULL;
if (acedEntSel("\nSelect first curve: ",en,asDblArray(p)) != RTNORM) return;
if (acdbGetObjectId(objId1,en) != Acad::eOk) return;
AcDbObjectPointer
pCurv1(objId1,AcDb::kForRead);
if (acedEntSel("\nSelect second curve: ",en,asDblArray(p)) != RTNORM)
return;
if (acdbGetObjectId(objId2,en) != Acad::eOk) return;
AcDbObjectPointer pCurv2(objId2,AcDb::kForRead);
if ((pCurv1.openStatus() == Acad::eOk) &&
(pCurv2.openStatus() == Acad::eOk)) {
AcDbPolyline *pPoly1 = AcDbPolyline::cast(pCurv1.object());
AcDbPolyline *pPoly2 = AcDbPolyline::cast(pCurv2.object());
AcGePoint3dArray points;
es = pPoly1->intersectWith(pPoly2, AcDb::kOnBothOperands, points);
int len;
if ((es != Acad::eOk) || ((len = points.length()) == 0)) {
AcGePoint3d point;
double params;
unsigned int num = pPoly2->numVerts();
AcDbMPolygon mpol;
AcGeIntArray ar;
mpol.appendLoopFromBoundary(pPoly1,false);
long cont;
for (cont=0; cont < (num - 1); cont++) {
pPoly2->getPointAtParam((double)cont, point);
if (mpol.isPointInsideMPolygon(point, ar) > 0) {
acutPrintf("\nInside!");
} else {
acutPrintf("\nNOT Inside!");
}
}
} else {
acutPrintf("\nNOT Inside!");
}
}
}//end of command PINP
