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Look at the method OffsetPoints in The Building Coder samples:
/// <summary>
/// Offset a list of points by a distance in a
/// given direction in or out of the curve loop.
/// </summary>
public static IEnumerable<XYZ> OffsetPoints(
List<XYZ> pts,
double offset,
XYZ normal )
{
CurveLoop curveLoop = CreateCurveLoop( pts );
CurveLoop curveLoop2 = CurveLoop.CreateViaOffset(
curveLoop, offset, normal );
return curveLoop2.Select<Curve, XYZ>(
c => c.GetEndPoint( 0 ) );
}
It was implemented to support offsetting of point with no edges or curves attached and seems to solve the problem discussed here:
https://forums.autodesk.com/t5/revit-api-forum/offset-xyz-points/m-p/8665334
Your curve loop needs to be closed and contiguous, I assume, all edges pointing in the same direction.
Then, if it is in the XY plane, providing (0,0,1) as the normal vector will offset inwards, and (0,0,-1) outwards, or vice versa, depending on whether your curve loop is oriented clockwise or anticlockwise.
Why tessellate your boundary curves? You can add the untessellated original curves to the curve loop, can't you? More elegant...
Since you loop over each of the `segmentList` objects and call `SetCropShape` repeatedly for each one of them, the last one in your loop will win, and all other settings will be overwritten by that.
Have you checked whether the first boundary segment loop is the outer one, always, reliably?
If so, you will probably be better off just using that, and skipping all the subsequent (presumably inner) loops.
Oh dear, a room can be split into several components as well, can't it? In that case, there may be several disjunct outer loops.
Lots of special cases to handle... if the BIM creator is really weird, that is...
Thank you Jeremy for you responses.
When working on my code i like to create small working packages and a test revit project to test them on.
The image below is my test revit project with 5 rooms.
The reason i tessellate the boundary curve is that it is the only way i have been able to get a boundary curve that follows the boundary my test rooms of which some have curved walls see image below?
The fact that my original code above provides a cropped boundary would indicate that the original curve loop is closed and continuous.
I have also assumed it is the tessellated boundary points that i need to utilise to get the offset Cropped Boundary Curve?
I had previously tested the code you suggested but have tested again and still with no look the full code is below.
public void CropAroundRoom(Autodesk.Revit.DB.Architecture.Room room, Autodesk.Revit.DB.View view)
{
List<XYZ> points = new List<XYZ>();
if (view != null)
{
IList<IList<Autodesk.Revit.DB.BoundarySegment>> segments = room.GetBoundarySegments(new SpatialElementBoundaryOptions());
if (null != segments)
{
foreach (IList<Autodesk.Revit.DB.BoundarySegment> segmentList in segments)
{
CurveLoop loop = new CurveLoop();
foreach (Autodesk.Revit.DB.BoundarySegment boundarySegment in segmentList)
{
points.AddRange(boundarySegment.GetCurve().Tessellate());
}
CurveLoop loop2 = new CurveLoop();
double offset = 2.0;
XYZ normal = new XYZ(0,0,-1);
List<XYZ> pts = OffsetPoints(points,offset,normal).ToList();
for(int ip=0; ip< points.Count-1; ip++)
{
Line l = Line.CreateBound(pts[ip],pts[ip+1]);
loop2.Append(l);
}
ViewCropRegionShapeManager vcrShapeMgr = view.GetCropRegionShapeManager();
bool cropValid = vcrShapeMgr.IsCropRegionShapeValid(loop);
if (cropValid)
{
vcrShapeMgr.SetCropShape(loop);
break;
}
}
}
}
}
public static CurveLoop CreateCurveLoop(List<XYZ> pts )
{
int n = pts.Count;
CurveLoop curveLoop = new CurveLoop();
for( int i = 1; i < n; ++i )
{
curveLoop.Append( Line.CreateBound(pts[i - 1], pts[i] ) );
}
curveLoop.Append( Line.CreateBound(pts[n], pts[0] ) );
return curveLoop;
}
public static IEnumerable<XYZ> OffsetPoints( List<XYZ> pts,double offset,XYZ normal )
{
CurveLoop curveLoop = CreateCurveLoop( pts );
CurveLoop curveLoop2 = CurveLoop.CreateViaOffset( curveLoop, offset, normal );
return curveLoop2.Select<Curve, XYZ>( c => c.GetEndPoint( 0 ) );
}On the 2nd pass through the CreateCurveLoop for loop it crashed with the following error "Curve length is too small for Revit's tolerance (as identified by Application.ShortCurveTolerance)" which may be understandable if the room was very small but it is 4.5m x 3.5m
I have also indicated below the List<XYZ> pts data passed into OffsetPoints.
I am at a loss as to what i am doing wrong?
As can be seen from my test project the room are simple and the boundary segment loop will be the outer.
For more complex situations were this is not the case I assume the following is still the best solution.
https://thebuildingcoder.typepad.com/blog/2008/12/2d-polygon-areas-and-outer-loop.html
This will be my next part of the code to resolve once I can get the CreateViaOffset to work.
Regards
Stephen
Can you share your sample model? Preferably including your complete add-in solution or macro or whatever it is? Thank you!
Hi,
I think there may be a problem because of too much self-intersections, inside the Revit API method itself.
Imagine all the small line segments made from the curve, drawn in a given distance.
In fact, they form another arc, but somewhat twisted.
Why not create an offset loop of the boundary containing the original curve and just tesselating the result - if necessary at all?
Revitalizer
> Is there a better alternative to achieve the same goal?
Yes, I believe so. The curve you tessellate is a curve. The curve loop you are assembling from the tessellation line segments is a collection of curves.
I assume you can skip the tessellation completely and just add the original curve to the curve loop as is.
KISS!
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