Finding block positions in an external reference

[jmaniaAZNPL]

I have written some code to grab block references from an external references dwg file. I can get the references fine but when i draw the positions of the blocks they are all slightly off. See the pictures below.

The white Xs mark where the position is being calculated in my code. You can see that they are pushed over to right and rotated.

This picture shows the blocks open in the external reference where they have positions located at the center of each block. Below is the code I am using to draw the Xs.

	std::vector<AcDbEntity*> points;
	getObjects( L"xModel", L"_MODULE POINT", &points );
	for( int i = 0; i < points.size(); i++ )
	{
			
		AcDbBlockReference *ref = NULL;
		ref = AcDbBlockReference::cast( points.at(i) );

		if( ref != NULL )
		{
			modulePoint[0] = ref->position().x;
			modulePoint[1] = ref->position().y;
			modulePoint[2] = 0;
			//acedTrans( modulePoint, &wcs, &ucs, FALSE, modulePoint );
			createLine( modulePoint[0]-2, modulePoint[1], modulePoint[0]+2, modulePoint[1], L"0" );
			createLine( modulePoint[0], modulePoint[1]-2, modulePoint[0], modulePoint[1]+2, L"0" );

		}

		points.at(i)->close();
	}

I have attempted to translate the points from wcs to ucs but that does not seem to help.

[Alexander.Rivilis]

You must consider AcDbBlockReference::blockTransform transormation for xref.

[jmaniaAZNPL]

Thank you for the answer. I have tried that and I get the points far out in space shown in the following. Am I missing something else that I have to do?

The updated code.

	std::vector<AcDbEntity*> points;
	getObjects( L"xModel", L"_MODULE POINT", &points );
	for( int i = 0; i < points.size(); i++ )
	{
			
		AcDbBlockReference *ref = NULL;
		ref = AcDbBlockReference::cast( points.at(i) );

		if( ref != NULL )
		{
			AcGeMatrix3d trans = ref->blockTransform();
			AcGeVector3d pnt;
			pnt.x = ref->position().x;
			pnt.y = ref->position().y;
			pnt.z = 0;

			pnt.transformBy( trans.inverse() );
			

			modulePoint[0] = pnt.x;
			modulePoint[1] = pnt.y;
			modulePoint[2] = 0;

			//acedTrans( modulePoint, &wcs, &ucs, FALSE, modulePoint );
			createLine( modulePoint[0]-2, modulePoint[1], modulePoint[0]+2, modulePoint[1], L"0" );
			createLine( modulePoint[0], modulePoint[1]-2, modulePoint[0], modulePoint[1]+2, L"0" );
		}

		points.at(i)->close();
	}

[Alexander.Rivilis]

blockTransform() not for AcDbBlockReference in external reference but for AcDbBlockReference of external reference attached to current drawing.

Also you have to consider position of AcDbBlockReference of external reference.

[jmaniaAZNPL]

Thanks for the clarification Alexander you are always so helpful. I am trying to figure out how to get the AcDBlockReference of the external reference but I am having some trouble as I only grab the BlockRecord for the DWG file in my code. Maybe I am misunderstanding some of the workings of external references in ARX as I am very new to it.  Below is the function I am using to get the blocks from the external references I was hoping you could take a look if you have some time. Thank you in advanced.

bool getObjects( ACHAR *xRefName, ACHAR *layer, std::vector<AcDbEntity*> *objects, AcGeMatrix3d *transform )
{
	Acad::ErrorStatus errorStatus;
	AcDbDatabase *database = acdbHostApplicationServices()->workingDatabase();
	AcDbBlockTable *blockTable = NULL;
	AcDbBlockTableRecord *modelBlockTableRecord = NULL;
	AcDbBlockTableRecord *blockTableRecord = NULL;
	AcDbDatabase *xRefDatabase = NULL;
	const ACHAR *xRefPath = NULL;
	AcDbDatabase *xRefDWGDatabase = NULL;
	AcDbBlockTable *xRefBlockTable = NULL;
	AcDbBlockTableRecord *xRefBlockTableRecord = NULL;

	//Get the block table for our database
	errorStatus = database->getBlockTable(blockTable, AcDb::kForRead);
	if( errorStatus != Acad::eOk )
	{
		acutPrintf(L"\nError getting block table %s", acadErrorStatusText( errorStatus ) );     
		return false;
	}
	//Get the table record in model space
	errorStatus = blockTable->getAt(ACDB_MODEL_SPACE,modelBlockTableRecord,AcDb::kForRead); 
	if( errorStatus != Acad::eOk )
	{
		acutPrintf(L"\nError getting model space block table record %s", acadErrorStatusText( errorStatus ) );     
		blockTable->close();
		return false;
	}
	//Get the block table record for the external reference
	errorStatus = blockTable->getAt( xRefName, blockTableRecord, AcDb::kForRead );
	if( errorStatus != Acad::eOk )
	{
		acutPrintf(L"\nError could not get xref %s %s", xRefName, acadErrorStatusText( errorStatus ) ); 
		modelBlockTableRecord->close();
		blockTable->close();
		return false;
	}

	xRefDatabase = blockTableRecord->xrefDatabase(true);

	if( xRefDatabase == NULL )
	{
		acutPrintf(L"\nCould not get external reference database" );
		modelBlockTableRecord->close();
		blockTable->close();
		blockTableRecord->close();
		return false;
	}
	//Get path for external reference dwg file
	xRefPath = acdbOriginalXrefFullPathFor( xRefDatabase ); 
	if( xRefDatabase == NULL )
	{
		acutPrintf(L"\nCould not get external reference path" );
		modelBlockTableRecord->close();
		blockTable->close();
		blockTableRecord->close();
		return false;
	}
	//Get database for the external reference drawing
	xRefDWGDatabase = new AcDbDatabase(Adesk::kFalse);
	errorStatus = xRefDWGDatabase->readDwgFile(xRefPath);
	if( errorStatus != Acad::eOk )
	{
		acutPrintf(L"\nError could not read xref file %s", acadErrorStatusText( errorStatus ));     
		modelBlockTableRecord->close();
		blockTable->close();
		blockTableRecord->close();
		return false;
	}
	//Get the block table for the open model reference file
	errorStatus = xRefDWGDatabase->getBlockTable( xRefBlockTable, AcDb::kForRead );
	if( errorStatus != Acad::eOk )
	{
		acutPrintf(L"\nError could not load xref block table %s", acadErrorStatusText( errorStatus ));     
		modelBlockTableRecord->close();
		blockTable->close();
		blockTableRecord->close();
		return false;
	}

	//Get the definition for the block in the the external reference
	errorStatus = xRefBlockTable->getAt( L"TRINA 335W MODULE", xRefBlockTableRecord, AcDb::kForRead );
	if( errorStatus != Acad::eOk )
	{
		acutPrintf(L"\nError could not get xref block table record %s", acadErrorStatusText( errorStatus ));     
		modelBlockTableRecord->close();
		blockTable->close();
		blockTableRecord->close();
		xRefBlockTable->close();
		return false;
	}

	AcDbObjectIdArray blockIds;
	errorStatus = xRefBlockTableRecord->getBlockReferenceIds( blockIds );
	if( errorStatus != Acad::eOk )
	{
		acutPrintf(L"\nError could not get xref block ids %s", acadErrorStatusText( errorStatus ));     
		modelBlockTableRecord->close();
		blockTable->close();
		blockTableRecord->close();
		xRefBlockTable->close();
		xRefBlockTableRecord->close();
		return false;
	}

	for( int i = 0; i < blockIds.length(); i++ )
	{
		AcDbEntity *ent = NULL;
		acdbOpenObject( ent, blockIds.at(i), AcDb::kForRead );
		if( ent != NULL )
		{
			objects->push_back( ent );
		}		
	}

	modelBlockTableRecord->close();
	blockTable->close();
	blockTableRecord->close();
	xRefBlockTable->close();
	xRefBlockTableRecord->close();
	return true;
}

[Alexander.Rivilis]

One Xref can be attaching many times in different positions, different rotations, different scales. Information of position/rotation/scales is in AcDbBlockReference's which refer to AcDbBlockTableRecord  of xref. So you can not get information about position of entities into Xref if you have only name of Xref but have not information of Xref position/rotation/scale (e.g. AcDbBlockReference of Xref).

[Alexander.Rivilis · Accepted solution]

@jmaniaAZNPL

Hope this video help you understand what wrong in your algorithm:

[jmaniaAZNPL]

Thank you so much. I grabbed the first reference to the xref and got the translation.

[bjevtic]

Dear Alex,

I notice you have not only ArxDbg (very useful tool) in right-click shortcut, but also MgdDbg.

If you don't mind me asking, what is MgdDbg and what is it used for?

[Alexander.Rivilis]

---

@bjevtic wrote:

Dear Alex,

I notice you have not only ArxDbg (very useful tool) in right-click shortcut, but also MgdDbg.

If you don't mind me asking, what is MgdDbg and what is it used for?

---

MgdDbg is a analog of ARXDBG created with help of AutoCAD .NET API. Sometimes it is more convenient than ARXDBG.

https://github.com/ADN-DevTech/MgdDbg

There is a ready to use bundle of MGDDBG for AutoCAD versions up to 2018: http://adn-cis.org/assets/gallery/AutoCAD/MgdDbg.zip

[bjevtic]

Thanks