Brep Split Fails

Rhino Developer
1

I found some brep split fail, and after rotate some degree, it succeded.(the same brep)

brepspliterror.jpg1547×521 226 KB

brepspliterror2.3dm (112.7 KB)
brepspliterror.gh (9.1 KB)

2

Hi SKSON,

the brep not splitted has some overlap slopes in it self. To find where these are located, create an intersection with the splitter which results in 3 intersection curves. I´m not shure why you created the object to split with such topology, but you could duplicate the surface borders from it and create an equivalent “light” planar surface from the duplicated border curve. Then split works.

c.

3

Dear clement, Thank you for your reply.
The brep is made of ‘network surface’, it is sample of lens surface.
I’m trying to make raytracing sw and for faster simulation I have to partition breps.
So, it is problem for me that such as the attached brep can not be splitted.
most of work light lens will have much complicated pattern.
The attached surface(brep) is not twisted and I do not understand why there is overlap slopes, and
after I just rotate the brep a little it is splitted well. So I still think it is bug…and even if there are overlap slopes I hope the brep to be splitted well without further treatment.

4

This probably should. I’m posting as a bug. Thanks for reporting.

– Dale

5

Although not reported by the Check command, this is a bad surface. It almost doubles back on itself. Here is a curvature analysis at a point on the surface. It shows that the Maximum principal curvature ~10^9.

Surface curvature evaluation at parameter (69.6996, 0.201954):
3-D Point: (-22.4264, 10.3358, 2.92736)
3-D Normal: (-0.999638, 0.0235761, 0.0129437)
Maximum principal curvature: -6.55402e+009 (0.0265993, 0.795369, 0.605541)
Minimum principal curvature: -4.3358e-009 (0.00398125, 0.605667, -0.795709)
Gaussian curvature: 28.417
Mean curvature: -3.27701e+009
Select point on surface for curvature measurement. Press Enter when done ( MarkCurvature=No ):

6

Thank you very much, Mr. Dale
I hope to use fixed brep.split function ASAP.
Thank you very much.

ps : I made the surface using an arc pattern and a spline, and copies of them. I used snap(end point) to pattern the arc. If there is doubles back on the surface, even though I didn’t intened, I think the network surface function also has to be reviewed.