There is problem with MoI where normals face the wrong way, like after a mirror operation normals will be flipped upside down. This is easy to see after an export and import inside another program. Is this a known issue? Is it something I am doing wrong?

Yes, this is what problem I was having. I posted about this yesterday, asking about
a regenerate tool, which I thought would rebuild the piece with the normals facing outward.

It would be helpful if there as a way to tell moi to make all normals face outward.
Or is there a tool already that does this in MOI.
Let us know!
thanks
Mike Fitz
www.3dartz.com

No, I think this is just a bug if using the mirror tool, as it flips the normals. But for the rest of the modeling process a normals recalculation would be nice.

Hi Val - I'll take a look at tuning this up for Mirror when I get back from vacation. For v1 there aren't going to be any manual normal-orienting tools inside of MoI because there aren't really any operations currently inside of MoI that are dependent on one particular orientation. For V2 I would like to add some kind of manual "flip" function to help for exporting, where the program that you are exporting to does need a particular orientation.

Mike Fitz wrote:
> It would be helpful if there as a way to tell moi to make all normals face outward.
> Or is there a tool already that does this in MOI

The Join tool will do this if all your pieces join together to make a fully closed solid. Then the normals will point "outward" from the solid.

But if the object is not a fully closed solid (if there are any edges not joined to another edge), then it is not easy for MoI to automatically analyze the object to determine outside/inside type categorization.

- Michael

>For V2 I would like to add some kind of manual "flip" function to help for exporting,
>where the program that you are exporting to does need a particular orientation.

Any word on that? (yes, i know the post I'm responding to is old)

-Nick

Hi Nick - nothing new on that front yet.

- Michael

OK, thanks. Just wanted to make sure I didnt miss it. ;)

Glad I spotted this - noticed the normals problem for the first time yesterday. Now I know it's MoI and not me I can workaround it.

The reason I brought this up is MoI is flipping the normals when they get 'seperated'. Has it always been like this and I never noticed? If you create a solid box, then seperate it, and take it into Rhino, all the surfaces are pointing inward. Is that 'normal' for nomals? (har har)

-Nick

Hi Nick,

> The reason I brought this up is MoI is flipping the normals
> when they get 'seperated'. Has it always been like this and
> I never noticed?

No, it sounds like a bug. MoI does some work when you do a Separate so that all the pieces should retain the orientation of the original solid. So for instance if you do a Shell, Offset, or Extrude after that on the individual surfaces the results of those operations go towards the same direction as the solid pieces do.

But maybe something is not quite right with that for file saving, I'll take a look.

- Michael

Hi Nick - yeah this was a problem with writing non-solids to a .3dm file.

I've made a fix for the next beta, so that if you do an Edit/Separate of a solid into individual surfaces and then save those surfaces into .3dm, when you bring them into Rhino the surface normals will be pointing to the same direction as the outside direction of the original solid.

Thanks for mentioning that this was not working as expected!

- Michael

>Thanks for mentioning that this was not working as expected!

You know what they say about 'blind squirrels'. ;)

Hi Nick, I also did a tune-up for mirror so that with non-solid surfaces, the surface normal direction will stay consistent with the original when mirroring, instead of the normals getting flipped.

Kind of an overhaul of normals handling for non-solids in general. I think it should solve many of these problems but there are a fair number of changes so please be on the lookout for any bugs in this area for the next beta.

- Michael

Thanks Michael, now I won't have to worry so much about only exporting solids.

Is surface assignments going to be in the next Beta?

-Will

Hi Will,

> Thanks Michael, now I won't have to worry so
> much about only exporting solids.

Well, it can still be better to export solids. Even with these changes, MoI still does not know which direction should be the "outside" if you create an open surface initially.

However, there will now be more consistency, the normals of an open surface will now not flip when doing mirroring or when saving to .3dm, and I've also done some work to make the results consistent when you do stuff like cut something up into pieces.

However, none of this "maintain consistent direction" work will help in the case where the normal direction on an open surface is not initially going in the direction that you want. I do expect to have a Flip command at some point to let you see and change this though.

But keeping things consistent through operations and saving is a good step forward at least. It's one necessary part of the whole thing.


> Is surface assignments going to be in the next Beta?

I hope so, but I still have a fair amount of work to do to finish it up though. I've been kind of side tracked for a bit with some other work to make the export meshing multi-core enabled to speed it up and make it not freeze the UI while it is calculating.

- Michael

Sounds great all around Michael - thanks for your hard work!

-Will