Explode Closed Planar Curve Using RhinoCommon

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Permalink Reply by David Rutten on April 19, 2013 at 3:02pm

I wrote a special exploder that handles all curve types individually.

protected bool CurveSegments(List<Curve> L, Curve crv, bool recursive)
{
if (crv == null) { return false; }

PolyCurve polycurve = crv as PolyCurve;
if (polycurve != null)
{
if (recursive) { polycurve.RemoveNesting(); }

Curve[] segments = polycurve.Explode();

if (segments == null) { return false; }
if (segments.Length == 0) { return false; }

if (recursive)
{
foreach (Curve S in segments)
{
CurveSegments(L, S, recursive);
}
}
else
{
foreach (Curve S in segments)
{
L.Add(S.DuplicateShallow() as Curve);
}
}

return true;
}

PolylineCurve polyline = crv as PolylineCurve;
if (polyline != null)
{
if (recursive)
{
for (int i = 0; i < (polyline.PointCount - 1); i++)
{
L.Add(new LineCurve(polyline.Point(i), polyline.Point(i + 1)));
}
}
else
{
L.Add(polyline.DuplicateCurve());
}
return true;
}

Polyline p;
if (crv.TryGetPolyline(out p))
{
if (recursive)
{
for (int i = 0; i < (p.Count - 1); i++)
{
L.Add(new LineCurve(p[i], p[i + 1]));
}
}
else
{
L.Add(new PolylineCurve(p));
}
return true;
}

//Maybe it's a LineCurve?
LineCurve line = crv as LineCurve;
if (line != null)
{
L.Add(line.DuplicateCurve());
return true;
}

//It might still be an ArcCurve...
ArcCurve arc = crv as ArcCurve;
if (arc != null)
{
L.Add(arc.DuplicateCurve());
return true;
}

//Nothing else worked, lets assume it's a nurbs curve and go from there...
NurbsCurve nurbs = crv.ToNurbsCurve();
if (nurbs == null) { return false; }

double t0 = nurbs.Domain.Min;
double t1 = nurbs.Domain.Max;
double t;

int LN = L.Count;

do
{
if (!nurbs.GetNextDiscontinuity(Continuity.C1_locus_continuous, t0, t1, out t)) { break; }

Interval trim = new Interval(t0, t);
if (trim.Length < 1e-10)
{
t0 = t;
continue;
}

Curve M = nurbs.DuplicateCurve();
M = M.Trim(trim);
if (M.IsValid) { L.Add(M); }

t0 = t;
} while (true);

if (L.Count == LN) { L.Add(nurbs); }

return true;
}

--

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by Mostapha Sadeghipour Roudsari on April 19, 2013 at 3:46pm

Thanks David! Continuity trick did it.

Permalink Reply by Ben Howes on May 8, 2013 at 10:16am

David,  I'm not able to detect Arcs with this function. 

I want to find the edge types of a planar surface in a compiled component (I'm using a Brep input in the C# component to describe how I am using the GH_Surface.Value in my compiled component).  Images and GH file attached.  Am I joining the curves incorrectly before passing the polycurve into your function?  Any thoughts?

Attachments:

• explodeCurveScript.gh, 5 KB