Hiding and showing objects with shut lines

Hi @pascal
I’ve been meaning to report this more than a few times, but never got around to it (or maybe I did report it and just forgot?). If an object has shut lines enabled, it seems as if they are recalculated every time the obejct has been hidden away, and not only once, but twice, if you use ShowSelected: recalcute for selecting the objects to show and recalculate for actually showing the object.

When working with complex geometry and fine render meshes, this can take a while (to say the least, especially if combined with displacement!!! :scream:), so would it be possible to keep the rendermesh intact when hiding an object with shut lines? By the way: it also recalculates objects with shut lines if an object WITHOUT shutlines is hidden and you then use ShowSelected to unhide other objects - although it “only” happens once, as the command is completed (after selecting which object(s) to show). This goes for both V6 and V7 WIP.

Could this please be tuned up - it seems like a waste of computing time. Also, it seems that none of the other “modifiers” - curve piping, thickness, edge softening, displacement - suffer from this bug. Or maybe it’s just my system being really weird?

TIA, Jakob

OK, so did some more testing, and it seems, that this is only the case with more complicated shut lines. A simple line on a simple box is instant, but if it’s anything remotely complicated, it the recalculation happens every time.
HTH, Jakob
Edit: It might be that shut lines going over surface boundries is the culprit for the recaculation. If a simple box has a single shutlines (eg a circle on the top surface) that stays within the edges of the surface, no recalculation… No wait… I take it back. Sometimes it recalculates, sometimes it doesn’t… Very weird!

OK, so…
Look at the attached file. A simple box with a simple circular shut line on the top surface.
A: Hide the box, the show the box; No recalculation
B: Hide the box, showselected the box; Recalculation x 2
C: Hide the circle; Recalculation
D: Show the circle; Recalculation
E: Hide the circle again, showselected the circle; Recalculation x 2 (the first time when the circle is hidden)
Something needs to be tuned up, I think.
shoddy shut lines.3dm (280.6 KB)

Hi Jakob - thanks, yes, I’ve been running into this myself lately.

RH-58743 Shutline recalculation
RH-58744 Shutline toggle


Hi @pascal
Just ran into this again today - seems like no improvements have been made? Shut lining is still recalculating on hide, show, showselected - even when it’s not the shut lined object being hidden/shown. If this feature is supposed to be any good for quick, not fully modeled shut lining, it needs to be a one-off calculation, not something that Rhino has to do time and time again. If combined with eg. displacement, it can take a really long time for these calculations, even on a fairly powerful PC.

Hi Jakob - just judging from the comments on the first item, there is at least some work done there but I don’t know of any ‘breakthrough’…


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Hi @pascal
I did see the comment from @DavidEranen, and speeding up the calculations is of course great - but is it really necesarry to recalculate every single time? Wouldn’t it be possible to somehow cache/save the modified render mesh? Or is that what is already being done, and it’s the “finding the modified render mesh” that’s taking time? Sorry if I’m asking stupid questions!

Hi Jakob - I don’t think these questions are stupid at all but… I know little, if anything, more then you do about the details - I’ll let David give a real answer…