Trim floors in GH

Evening grasshoppers! :]

I've been attempting to trim my floors since 8am this morning [its now 7pm!] and am having difficulties!..

I have tried using pretty much every boolean command [under the intersect tab] but cant get any results!

I think my main issues are:-

1] I'm not 100% sure which trim/boolean command i should use
2] I'm not 100% sure which stage of the operation i should insert a trim command i.e. do i trim the initial curves, the planar surfaces of the curves, or the extrusions of the planar surfaces?

Again, I've tried all options but no luck.

An image of the dilemma is below. Any help at all would greatly appreciated guys, I've ran out of options!

Jali

Replies to This Discussion

Permalink Reply by Andrei Raducanu on January 9, 2010 at 2:42pm

i don't have a solution, but try to do the operation manually in rhino. if it doesn't work there either, some of the objects created through GH are causing problems. try to find out which, it might get you closer to a solution.
i'm going through something similar now as well.

Permalink Reply by jali on January 9, 2010 at 2:48pm

Hey Andrei,

I'm kind of working backwards with my scheme. I modeled the geometry that i want to achieve in Rhino with no problems, and so now, as a way of teaching myself, I'm trying to replicate it in grasshopper.

As a last resort i will probably just trim in Rhino but really want it in GH.

Permalink Reply by Andrei Raducanu on January 9, 2010 at 2:51pm

i wasn't suggesting to trim in rhino just to get rid of it, but rather, to see where the problem lies.

Permalink Reply by jali on January 11, 2010 at 11:56am

Hey all!

I've progressed slightly - the floors have been trimmed, but as a result, the solids which i created in rhino to trim the floors and defined as Breps in GH have appeared as part of the GH composition!

The preview in the BRep command that they are referenced in is switched off, but i cannot seem to get rid of them. [See Below]

Any help would be greatly appreciated guys!

Jali

file also attached for larger view...

Attachments:

grasshopper trim help 02.jpg, 87 KB

Permalink Reply by Andrei Raducanu on January 11, 2010 at 12:01pm

bake the dif component, see if you get the floors only

Permalink Reply by jali on January 11, 2010 at 12:20pm

Hey Andrei,

Just baked it now, and unfortunately I get the solids too..

But it appears that a solid is baked for every floor that it has cut through, so when baked, that solid is in fact about 23 solids in the same place :S

Permalink Reply by Andrei Raducanu on January 11, 2010 at 12:29pm

did you change the name of the solid difference component? it usually comes in SDiff (you might like migrating to icons view, i did)
i'm asking to be sure you used the solid difference component

Permalink Reply by jali on January 11, 2010 at 12:35pm

yeah its deffo the solid difference. i've tried the trim solid command too...That gives very bizarre results and chooses to delte random floors..

I think i might re-draw the solids used for trimming and see where that takes me. Would you recommend trimming the floors with a solid or a planar srf?

Permalink Reply by Andrei Raducanu on January 11, 2010 at 12:58pm

upload the definition and the rhino file, might be easier to see what's going on and maybe find a solution

Permalink Reply by Benjamin Golder on January 11, 2010 at 1:30pm

I've found that using the Booleans on solids can be a bit messy. This also the case in rhino when I try too Boolean too many things at the same time. I think the problems I run into with the booleans as two kinds: too much, or normal problems. Too much is when I simply Boolean huge amount of things at the same time and it causes an error. I can fix this by doing booleans in smaller quantities. Normal problems are when the inside/outside of one more breps is not sufficiently determined, and this usually makes for some zany results. In rhino, you can simply use the "dir" command to see which way the normals are pointing on a polysurface. In grasshopper, you can show the normal vector with an evaluate surface and vector display.

Sometimes, even after checking normals, I've still run into problems using booleans in grasshopper. Try using explode on some breps, then flip, then join, to turn some breps inside out and get them working properly. If you can't seem to figure out which breps are inside out, then you can create a point that is definitely outside of the brep, and check to see if it is contained in the brep. The component that you use to check whether the point falls inside the brep will produce a Boolean value (true/false), that you can use to flip a breps surfaces or not.

You can often avoid inside/outside Boolean problems in the way you create your breps. If you are going to use them in a solid Boolean operation, be sure you know which way their normals point at each stage of construction.

Permalink Reply by jali on January 12, 2010 at 4:46am

Hey Everyone!

I've attached the GH definition and Rhino file to this reply, maybe someone can see what is going wrong?

Thanks for your input guys!

Jali

Attachments:

building floors with loft 9-01-10.3dm, 147 KB
building floors with loft 9-01-10.ghx, 204 KB

Permalink Reply by David Wood on January 12, 2010 at 5:35am

Hi Jali,

I've not had chance to look at your file yet, but Benjamin sounds like he's on the right track...

Also bear in mind coincident edges, faces and polysurface seams. All of which can cause booleans to fail in rhino modelling. Do you definately have a clear intersection?