pRegion->getAreaProp()

[EMD1954]

I want to let the user draw a complicated, 2D polyline, select it, and have it convert to a region so I can use the mass properties for a handful of tasks.  I've gotten to the point (following the samples) where I am able to create the region using

es = AcDbRegion::createFromCurves(curveSegs, regions);

AcDbRegion *pRegion;

pRegion =static_cast<AcDbRegion*>(regions[0]);  // I only have one element to pick

pRegion->getPlane(plane);

plane.getCoordSystem(origin, xAxis, yAxis);

es = pRegion->getAreaProp(origin, xAxis, yAxis, perimeter, area, centroid, momInertia,

prodInertia, prinMoments, prinAxes, radiiGyration, extentsLow, extentsHigh);

Then I save it to the database.  It works fine up to this point, but I get the wrong centroid (and different than the command line "MASSPROP")

Anything obvious?  Any help would be appreciated.

Thanks,

Ed

[owenwengerd]

What are the actual values that you're passing for the origin, xAxis, and yAxis arguments to getAreaProp()? Perhaps the MASSPROP command uses the UCS instead of the World coordinate system.

[EMD1954]

Origin is -50.1250, 76.0000, 0.0000 (it's the first point of the 3Dpoly that i created before it's turned into a region)
xAxis  is 1.0000, 0.0000, 0.0000
yAxis  is 0.0000, 1.0000, 0.0000

Function is attached as .txt file

Thanks,

Ed

[owenwengerd]

Try the WCS or UCS, then compare the results to MASSPROP.

[EMD1954]

Sorry for the trouble, but I don't understand.  I tried it in the "world" UCS, changed the view and set the UCS to "View" and even tried to set the UCS to "element".  What do you mean?  Sorry.

[owenwengerd]

I am referring to the first three arguments to getAreaProp(). For example, the WCS would be:

pRegion->getAreaProp(AcGePoint3d(0,0,0), AcGeVector3d(1,0,0), AcGeVector3d(0,1,0), ...);

[EMD1954 · Accepted solution]

Yes.  The problem was that "origin" was returning the first point of the original polyline, so I just zeroed the X and Y coordinates (I need Z for the proper elevation).  The xAxis and yAxis were correct:

pRegion->getPlane(plane);

plane.getCoordSystem(origin, xAxis, yAxis); 

origin.x = 0.0;

origin.y = 0,0;

Works great - thank you,

Ed