From point to surface, from surface to volume

Replies to This Discussion

Permalink Reply by David Rutten on March 11, 2010 at 5:24am

Hi AU,

delaunay triangulation can create a set of connected triangles from any collection of co-planar points. If however your points are clearly ordered in groups of 4, where each point in the group is supposed to become a corner of a rectangular nurbs patch, then you'll have to find a way to supply these points in the correct order to the [4Point Surface] component.

Another approach might be to connect all the points with a polyline, then create a planar surface from this curve.

Joining Breps is indeed best done with RhUtil.RhinoJoinBreps.

--
David Rutten
david@mcneel.com
Poprad, Slovakia

Permalink Reply by Wiet Mazairac on March 11, 2010 at 5:55am

Hi, tanks for your answer.

The points are more or less in a circle. So I don't think Del.Tri is in order.

I have been on it for a few hours now and I managed to create a ployline from the points, but I am still not where I want to be.
How do I create a surface from the polyline?
Do I need to convert the surfaces to breps or not.
And finaly, how to put these surfaces or breps together into a 3d-volume?

Every set op points is coplanar.
The points in every set are more or less in a circle and in the right order(0, 1, 2, 3,......)
Edit; See jpg for the polyline...


poly.JPG

Permalink Reply by Wiet Mazairac on March 11, 2010 at 6:47am

I forgot to mention that I am trying to code this in a Dot Net VB Script function in Grasshopper. I am not using the functions in Grasshopper.

Permalink Reply by David Rutten on March 11, 2010 at 7:29am

That's too bad, cause it would have been very easy in Grasshopper.

In order to create planar surfaces from closed curves you'll need to use RhUtil.RhinoMakePlanarBreps()

Making a polyline from a set of ordered points is very easy, it's a bit harder if the points weren't ordered. Just create a new OnPolyline and append all your points. Then close the polyline by appending the first point again at the end.

--
David Rutten
david@mcneel.com
Poprad, Slovakia

Permalink Reply by Wiet Mazairac on March 11, 2010 at 8:40am

Is it true that RhUtil.RhinoMakePlanarBreps() only accepts curves and no polylines?

If so, I have to convert the polyline to a onpolycurve.

Permalink Reply by David Rutten on March 11, 2010 at 10:33am

You have to convert it to OnPolylineCurve (just like you'd have to convert OnLines to OnLineCurve, OnArc to OnArcCurve etc.)

OnPolyCurve is a bit too complicated for what you need here.

--
David Rutten
david@mcneel.com
Poprad, Slovakia

Permalink Reply by Wiet Mazairac on March 11, 2010 at 4:07pm

Another question....

Now I have this....

x is a list of on3dpoints




Dim polyline As New OnPolyline
Dim i As int32
For i = 0 To 7
polyline.Append(x(i))
Next

polyline.Append(x(0))

Dim polylinecurve As New OnPolylineCurve(polyline)
Dim brep() As OnBrep
RhUtil.RhinoMakePlanarBreps(polylinecurve, brep)




the out of the vb.net function says......
....value of type ...... onpolylinecurve' cannot be converted to '1-dimensional array of ........ ioncurve'.......

How can I solve this????

Thanks for all the answers so far :)

Permalink Reply by Wiet Mazairac on March 12, 2010 at 2:05am

For those who care, this is the way to do it.
Pretty simple, but I am a newby, so it took a while.

x is a list of on3dpoints

Dim polyline As New OnPolyline
Dim i As int32
For i = 0 To 7
polyline.Append(x(i))
Next
polyline.Append(x(0))

Dim polylinecurve As New OnPolylineCurve(polyline)

Dim ioncurve(0) As ioncurve
ioncurve(0) = polylinecurve

Dim brep() As OnBrep = Nothing

RhUtil.RhinoMakePlanarBreps(ioncurve, brep)


David, thanks!

Permalink Reply by David Rutten on March 12, 2010 at 8:33am

I don't blame you for being confused. This is exactly the sort of thing we're trying to fix in our next SDK.

--
David Rutten
david@mcneel.com
Poprad, Slovakia