I have done things like you are trying to do for very big meshes. But I
didn't understand correctly what is your problem.
Does your problem is finding point (nodes) to curve distance? Or edge to
edge distance?
When you compare distances, a way to compute faster is to scape from sqrt.
For example
Slow way to compare the distance of a_point to a point-set:
For each point in point_set; sqrt(dot(point-a_point,point-a_point) <
distance;
Faster way to compare the distance of a_point to a point-set:
For each point in point_set; dot(point-a_point,point-a_point) <
distance**2;
Even faster way to compare the distance of a_point to a point-set:
temp=distance**2; For each point in point_set;
dot(point-a_point,point-a_point) < temp;
Good luck
Lie Pablo
On 6 August 2013 13:21, Uwe Schlifkowitz <schlifkow...@intales.com> wrote:
> Hi all,
>
> I am trying to find vertices that are near an edge within some kind of
> tolerance.
>
> Imagine lots of short edges intersecting a surface. The edges are
> parallel to the surface normal and evenly distributed over the surface.
> The surface has a mesh and I have a dictionary of said edges and a
> dictionary of mesh nodes (vertices).
>
> So what I'm trying to do is assign all nodes that are within ~3mm of an
> edge to that edge.
>
> I used BRepExtrema_DistShapeShape which seems to do the job quite well
> for small numbers of points and edges (600 points, 72 edges).
> For larger numbers however, the process consumes all available memory
> (16GB) and then hangs the machine.
>
> So my questions are:
> * Is there a better way to achieve what i want?
> * How can I reduce memory consumption?
>
> Unrelated question: why does the conversion from TopoDS_Vertex to gp_Pnt
> fail when i write TopoDS_Vertex instead of TopoDS_vertex? What exactly
> is the difference? If it's in the docs I must have missed it.
>
>
> Thanks,
> Uwe
>
> #---------------------------------------
> pntDic = {} # some dictionary of gp_Pnt
> curveDic = {} # some dictionary of TopoDS_Edge
> tol = 3
> curveToNode = {}
> for k in pntDic:
> for l in curveDic:
> v = BRepBuilderAPI_MakeVertex(pntDic[k])
> dist = BRepExtrema_DistShapeShape(v.Vertex(), curveDic[l])
> if dist.Value() <= tol:
> # assign curve to node
> # get normalized edge direction
> # get start and end vertex of edge
> ex = TopExp_Explorer(curveDic[l], TopAbs_VERTEX)
>
> # no need for a loop since we know for a fact that
> # the edge has only one start and one end
> c = ex.Current()
> cv = TopoDS_vertex(c)
> v0 = BRep_Tool_Pnt(cv)
> ex.Next()
> c = ex.Current()
> cv = TopoDS_vertex(c)
> v1 = BRep_Tool_Pnt(cv)
> dx = v1.X() - v0.X()
> dy = v1.Y() - v0.Y()
> dz = v1.Z() - v0.Z()
> edgeScaling = sqrt(dx ** 2 + dy ** 2 + dz ** 2)
> edgeDirection = [dx / edgeScaling,
> dy / edgeScaling,
> dz / edgeScaling]
> curveToNode[k] = (l, edgeDirection)
> del ex, v1, v0, dx, dy, dz, c, cv
> del edgeScaling, edgeDirection
> else:
> pass
> del v, dist
> #---------------------------------------
>
>
> --
> INTALES GmbH Engineering Solutions
> Uwe Schlifkowitz -- Software Engineer
> Innsbrucker Str. 1, A-6161 Natters
> Phone: +43 512 54611120 -- schlifkow...@intales.com
>
> _______________________________________________
> Pythonocc-users mailing list
> Pythonocc-users@gna.org
> https://mail.gna.org/listinfo/pythonocc-users
>
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