<?xml encoding=”UTF-8″>by Fenton Webb
Issue
When I apply a transformation to an AcDb2dPolyline that has a mirror component, the arcs of the reflected polyline go the wrong way. How can I avoid this?
Solution
If the transformation has a reflection or mirror component, the bulges need to be negated. This is done when the object is invoked with the mirror command, but not when calling the ARX function. The following sample does this.
void utilsmirror()
{
// select the 2d polyline
ads_name eName;
ads_point pt;
int res = ads_entsel(_T(“nPlease pick a polyline”), eName, pt);
if (res != RTNORM)
return;
// convert the ename to an ObjectARX objectid
AcDbObjectId id;
acdbGetObjectId( id, eName );
// now open the polyline2d for write
AcDbObjectPointer<AcDb2dPolyline> pPoly(id, AcDb::kForWrite);
// if ok
if (pPoly.openStatus() == Acad::eOk)
{
AcGeMatrix3d mat;
// setup a mirroring transform matrix
mat.setToMirroring( AcGePlane( AcGePoint3d::kOrigin, AcGeVector3d::kXAxis ));
// now mirror the polyline
pPoly->transformBy(mat);
// finally, iterate the vertexes and invert the bulges
AcDbObjectIterator *pIter = pPoly->vertexIterator();
for(; !pIter->done(); pIter->step() )
{
AcDbObjectId id = pIter->objectId();
AcDbObjectPointer<AcDb2dVertex> pVertex(id, AcDb::kForWrite);
if(pVertex.openStatus() == Acad::eOk)
pVertex->setBulge( –pVertex->bulge() );
}
delete pIter;
}
<span>else</span> <span>acutPrintf</span>(<span>_T</span>(<span>"nNot an AcDb2dPolyline..."</span>));}
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