bug?

Hey Guys,

this seemingly simple sort operation doesn't seem to be simply working any longer. Did I miss something ?

thanks

Curve[] crvs = roads.ToArray();
double[] xList = new Double[crvs.Length];

for(int i = 0; i < crvs.Length - 1; i++){

xList[i] = crvs[i].PointAt(0.5).X;

}

Array.Sort(xList, crvs);

A = crvs;

Replies to This Discussion

Permalink Reply by Steve Baer on May 25, 2011 at 1:56pm

I haven't tried this in Grasshopper, but the following code appears to work just fine. I also noticed that your for loop is short by one. You shouldn't subtract 1 from crvs.Length.

Random r = new Random();

Curve[] crvs = new Curve[30];

for (int i = 0; i < 30; i++)

{
  double x0 = r.NextDouble()*10;
  double y0 = r.NextDouble() * 10;
  double x1 = r.NextDouble() * 10;
  double y1 = r.NextDouble() * 10;
  crvs[i] = new LineCurve(new Point3d(x0, y0, 0), new Point3d(x1, y1, 0));

}
double[] xCrvs = new double[30];

for (int i = 0; i < 30; i++)

{
  xCrvs[i] = crvs[i].PointAt(0.5).X;

}

Array.Sort(xCrvs, crvs);



for (int i = 0; i < 30; i++)

{
  double x = crvs[i].PointAt(0.5).X;
  RhinoApp.WriteLine(x.ToString());

}

Permalink Reply by brendon_carlin on May 25, 2011 at 2:32pm

thanks steve,

yes, you are right about the -1. But I've done essentially the exact same thing you did, and the sort is not working properly.

Permalink Reply by David Rutten on May 26, 2011 at 9:51am

Hi Brendon,

trust me, Sort works fine. If it didn't, .NET would not be usable. I suspect you are probably not sorting the values you think you are sorting. This line:

crvs[i].PointAt(0.5).X;

is meaningless. The PointAt() method uses curve parameters. There is no guarantee that 0.5 is even a valid parameter on your curve. If you want the MidPoint, then consider using:

crvs[i].PointAtNormalizedLength(0.5)

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by brendon_carlin on May 26, 2011 at 10:05am

hmm, thanks david,

I did reparameterize the curves and check that the point was at 0.5.. but it wasn't working.

Permalink Reply by David Rutten on May 26, 2011 at 3:39pm

If the curves have arc-length parameter spacing then 0.5 on reparameterized curves probably is the midpoint, but not on your regular freeform nurbs curve.

Array.Sort() is not the problem here, the bug or oversight must be elsewhere. Can you post the files I need to replicate this?

David Rutten

david@mcneel.com

Poprad, Slovakia

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