IntersectWith XREF entities

[damir_vidakovic]

I'm trying to find intersections between current drawing entities, and attached XREF entities. 

So far I have made a function that enumerates all curve entities in the current drawing +  XREF curve entities.

I'm using acedSSGet with :n and later acedSSNameX for iterating through nested entities, that is entities inside XREF.

So far so good, I got the objectIds, but when I try to call intersectWith, I get no intersection points, and intersectWith returns eOk.

This is my code, I do not know what else to try.

static void multi_select_nested_entity(AcDbObjectIdArray &iaElementsInXref)
{
	// switch on the multi selection of nested entities
	setAllowDuplicateSelection(curDoc(), true);   
	curDoc()->inputPointManager()->turnOnSubentityWindowSelection();
	ads_name sset, eName;
	AcDbObjectId id;

	// in the mode "_:n" 
	//
	if (RTNORM == acedSSGet(L"_:n", NULL, NULL, NULL, sset))
	{
		std::set<AcDbObjectId> setIds;
		acutPrintf(L"\n");
		long len = 0;
		acedSSLength(sset, &len);
		for (long i = 0; i < len; i++)
		{             
			resbuf *rb = NULL;
			//  ssnamex() returns all selected nested entities
			//  
			if (RTNORM == acedSSNameX(&rb, sset, i))
			{
				resbuf *rbWalk = rb;
				while (NULL != rbWalk)
				{
					if (RTENAME == rbWalk->restype)
					{
						eName[0] = rbWalk->resval.rlname[0];
						eName[1] = rbWalk->resval.rlname[1];
							if (Acad::eOk == acdbGetObjectId(id, eName))
						{
//							acutPrintf(L"Entity %d: %x",i,id.asOldId());
							
							AcDbEntity *pEnt;
								if (Acad::eOk ==acdbOpenObject(pEnt,id,AcDb::kForRead))
							{
								if (pEnt->isKindOf(AcDbCurve::desc()))
								{
									acutPrintf(L"From XREF: (%s)\n", pEnt->isA()->name());                           
										setIds.insert(id);
								}								
									pEnt->close();
							}
							else
							{
								acutPrintf(L"\nCouldn't open object");
							}
						}
						//rbWalk = NULL; 
					}
					//else
					{
						rbWalk = rbWalk->rbnext;
					}
				}
				acutRelRb(rb);
			}
		}
		acedSSFree(sset);

		set<AcDbObjectId>::iterator it;
			for (it = setIds.begin(); it != setIds.end(); ++it)
		{
			iaElementsInXref.append(*it);
		}
	} 
		// swtich off
	setAllowDuplicateSelection(curDoc(), false);
	curDoc()->inputPointManager()->turnOffSubentityWindowSelection();
		
}

// - ARSXTestXrefIntersect.test command (do not rename)
static void ARSXTestXrefIntersecttest(void)
{
	AcDbObjectIdArray iaElementsInXref;
	//find all entities
	multi_select_nested_entity(iaElementsInXref);
	for (int i=0; i < iaElementsInXref.length(); i++)
	{
		AcDbEntity *ptrEntA;
		if (acdbOpenAcDbEntity(ptrEntA, iaElementsInXref[i], AcDb::kForRead)==eOk)
		{
			for (int j = i + 1; j < iaElementsInXref.length(); j++)
			{
				AcDbEntity *ptrEntB;
				if (acdbOpenAcDbEntity(ptrEntB, iaElementsInXref[j], AcDb::kForRead)==eOk)
				{
					AcGePoint3dArray points;
					if (ptrEntA->intersectWith(ptrEntB, kOnBothOperands, points)==Acad::eOk)
					{
						for (int k=0; k < points.length(); k++)
						{
							//CARSCDraw::circle(points[k], k+1, AcGeVector3d(0,0,1));
							acutPrintf(L"\nIntersection found at x=%.4f, y=%.4f", points[k].x, points[k].y);
						}
					}
					ptrEntB->close();
				}					
			}
			ptrEntA->close();
		}
	}
}

[owenwengerd · Accepted solution]

Xref entities (actually any entities in a block) are transformed by a AcDbBlockReference entity before being displayed. If you want to calculate an intersection, you need to account for that transformation.

[damir_vidakovic]

Do you mean I have to transform the entities by transformation matrix before the intersectWith call?

[damir_vidakovic]

Yes, that is it! If I move insert point of XREF to the 0,0 I get correct intersections. I believe I'll have to transform entities considering UCS from XREF to get correct results for every XREF.

[owenwengerd]

If you're not worried about performance, you may be able to use AcDbBlockReference::explode() to create transformed copies of the entities.