CGAL users discussion list

[Efraim Fogel <>]

Ben Supnik wrote:
> Hi Y'all,
>
> I have an arrangement (built out of join and difference operations on 
> polygons).  I am using an exact pred/exact constructions kernel and 
> half -frounding-math on.  I am in debug mode, so I have all warnings, 
> etc.
>
> After building my arrangement, I do an insert-curves on an 
> axis-aligned bounding box that sometimes overlaps the horizontal and 
> vertical edges of my map.
>
> If I insert the four sides using insert_curve, all is good.
> If I insert all four using insert_curves, I get an assertion failure 
> when trying to split a face.
>
> Now...looking at the code it seems clear that I should be using 
> insert_curve anyway; doing a full copy of the arrangement to put only 
> four curves in will be dominated by the copy cost.
There are cases where applying incremental inserts is more efficient 
than an applying an aggregate insert, especially when the number if 
input curves is small, but which copy of arrangement do you refer to?
> But...is there any case where the sweep-line-based insert_curves 
> should blow up?  I am concerned that either my map is secretly invalid 
> (it passes validation checks) or I have compiler settings such that my 
> numerics are not stable.
We are not aware of any bug of that sort. Try to come up with a test 
case that exposes the problem, and that we can reproduce, and we'll look 
at it.
> cheers
> ben


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