Split vs. Trim

[EighthDecay]

I think you answered your own question, it just deletes the unwanted portion just like in autocad, but I have a tendancy to use Split for every case. Almost never use the trim command in Rhino. :-)

[andrewjohn81]

split is often just easier to use. Since you can't zoom selected in the middle of a command it is simply hard to select the surface you want to trim away occasionally. Split, then delete the part you don't want.

Both commands create trimmed surfaces. Trim just deletes it for you.

For commands that won't work on trim surfaces try the _shrink command. It reduces the trim as much as possible. If it's something like a simple rectangle then you will no longer have a trim surface. So, if you trimmed something in a straight line it will end up not being a trimmed surface anymore.
Some trim surfaces, however, you just can't avoid.

[DarkSaturn]

I tend to use trim when working with curves, but go with split when working with surfaces. Quite often when the section of a surface you want to trim is obscured you can end up instead trimming the opposite section, in which case going with split would be the easier option. Otherwise it shouldn't really matter.

[Azeiku]

I see, so it's just preference of the split compared to trim. I get it.

I was curious if it put different attributes on the surface if you split compared to trimmed but according to both of your responses it seems not to do anything different. Just a different way.

andrewjohn81's point that it's just easier because picking the portion you want to trim is difficult sometimes makes sense to me. I think I'm going to use split from now on as well just because of this. I constantly am trying to get myself in a spot so I can pick the tiny little piece I want trimmed.

Thanks a ton!
Azeiku

[furo]

i totally agree with EighthDecay.. he said, what i'd say if i'd be first here;) so.. i don't know if there's any difference between trim and split.. rhino's not like maya's bezier curves,where's pretty difficult to trim any surface.. so, here's my two cents.. ;)

[andrewjohn81]

most people don't use bezier curves in maya. Trimming is pretty easy there too, if you know what you are doing.

[EHNisja]

I find that using trim will keep the parent's surface control point structure intact, while split will automaticaly shrink the two resulting surfaces. I favor using trim for that very reason. I work with may ProE files that keep the entire control set for a fillet as a tube, so that if you untrim the fillet a tube is avalible to work with. A flat planar surface will also untrim past its edge curves to give that little something extra to work with. I believe it has to do with their parametrics.

[KBOC]

I know there is a difference, I just can't tell you what it is... I know in some instances that the trim command won't work in which the split command does... but I can't tell you why.

[andrewjohn81]

keep in mind that since all that extra data is there your file size will be larger. If you never shrink surfaces your files will be, in some cases, 2 or 3 times larger than they need to be.

[KBOC]

Oh yes... I use BD a LOT in my modelling, though... tonnes of trimmed surfaces... doesn't bother me on file size since Rhino runs on a 80386... just fine :p

The truth is that if you save your models cleared of render meshing, you're file sizes will be a lot smaller.

[Teyon]

That's weird...in version 2, you split a surface and the control points for the surface that was removed is still there unless you shrink the trimmed surface (in this case trimmed refers to any cut surface).

[KBOC]

I'm still usin 1.1.

The control points don't go away, as the surface still exists, Rhino adds information to the surface to include the trim.

What I was saying is that even with that added information, it's nothing compared to the amount of memory that the preview meshes eat up. Clear those, when you save, you'll be happier :D

[Teyon]

What I was saying is that even with that added information, it's nothing compared to the amount of memory that the preview meshes eat up. Clear those, when you save, you'll be happier :D

LOL Amen to that! Lord knows Rhino likes to make big meshes for no good reason...

[ikkentobi]

LOL Amen to that! Lord knows Rhino likes to make big meshes for no good reason...

Its not Rhino witch ikes to make big meshes...
it just depends how you have set your meshing options!
Both, Rhino options and the options for your template.

[ikkentobi]

Theres another (maybe obvious) difference between Trim and Split:

You can't windowselect the objects to cut when using Trim. With Split you can!

Lets say you have 100 lines and you want to trim them all with 1 curve: With Trim you would first have to select the cutting curfe and then click 100! times to get the job done. While with Split you will be ask to select the objects to split first witch you can do with a crossing window and then you select your cutting curve. Now after splitting you can (again) windowselect all the remains not needed and delete them.

[Teyon]

Ikkentobi, I know this, for what I do, I tend to export untrimmed meshes. In the case of split or trimmed areas however, my point is that Rhino likes to make tris polygons at the areas that are split and that there's no reason for this. Rhino could easily translate those same areas to quad polys but for some reason it doesn't.

Anyone try the split by isocurve? Neat little tool, let's you split along a surface's U or V direction without the use of an external cutter like a curve or second object.

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