Surface Closest Point and Brep Closest Point

Hello, I cant seem to get the same values of distance from a point that the Surface Closest Point component gets when using either :

double dist = 0;
for(int i = 0; i < surface.Count; i++){

Brep b = surface[i].ToBrep();
dist = point.DistanceTo(b.ClosestPoint(point));

}

A = dist;

////or

double dist = 0;
for(int i = 0; i < surface.Count; i++){

double u;
double v;
surface[i].ClosestPoint(point, out u, out v);
dist = point.DistanceTo(surface[i].PointAt(u, v));

}

A = dist;

Replies to This Discussion

Permalink Reply by David Rutten on July 17, 2012 at 1:32pm

Hi Brendon,

if you convert a brep or brepface to surface, you lose trimming information. Could that be what's happening here? (I'm in the middle of a meeting now so can't test in depth)

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by brendon_carlin on July 17, 2012 at 1:45pm

thanks so much for replying promptly david,

I tried an untrimmed Surface, the first component uses the second bit of code, it doesn't convert to Brep.. It takes an untrimmed Surface:

double dist = 0;
for(int i = 0; i < surface.Count; i++){

double u;
double v;
surface[i].ClosestPoint(point, out u, out v);
dist = point.DistanceTo(surface[i].PointAt(u, v));

}

A = dist;

.. I am getting distances that are all over the place when compared with the standard component.

thanks again

Permalink Reply by David Rutten on July 17, 2012 at 1:56pm

Please post a file I can use to repeat this, I want to see the data in real time.

David Rutten

david@mcneel.com

Poprad, Slovakia

Permalink Reply by brendon_carlin on July 17, 2012 at 5:15pm

Thanks David,

It is working on Orthogonal Surfaces but not irregular ones, so I suppose its not a bug.. I just seem to remember that in earlier versions this code worked fine. I am getting numbers all over the place when I use Point3d.DistanceTo(Surface.PointAt(u,v)); Where as with your component it doesn't matter if the surf is orthogonal and aligned with the world

Attachments:

exampleFile.3dm, 32 KB
exampleFile.gh, 4 KB

Permalink Reply by David Rutten on July 18, 2012 at 3:53am

Well, the problem is that you're importing surfaces into the C# component. So your actual planar brep becomes untrimmed. Converting your surface back to a brep isn't going to retrim it.

I changed your input to a list of breps and rewrote the script a wee bit.

David Rutten

david@mcneel.com

Poprad, Slovakia

Attachments:

exampleFile.gh, 4 KB

Permalink Reply by brendon_carlin on July 18, 2012 at 10:21am

Hey david, its not working...

i did the same, I am getting some weird stuff even then, i attached an image in which the top tag value is from the gH component, the bottom value is from Brep Closest point and distance.. I will send you the files thanks

Permalink Reply by brendon_carlin on July 17, 2012 at 5:50pm

I suppose then this is merely a question of how I deal with irregular referenced surfaces ( it was shrunk).. I tried to reparameterize it in the code.. didn't work .

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