Show full version of the posting: Question Surface face normal direction

18.02.2017, 14:19
Hi!I link AutoCAD stuff in 3dsMax on daily basis. The models are created in AutoCAD and rendered in Max.Sometimes, the linked mesh has its faces oriented in the wrong direction. In 3dsMax, there is a modifier called Normals that lets you Flip all normals or Unify them.How do I flip the normal direction?For reference, in Rhino (which also is a CAD software) there is a command called DIR (

Vladimir Michl
20.02.2017, 13:07

There is a FlipFace utility for AutoCAD - see:

23.02.2017, 14:03
Thank you Vladimir!I tried this on polygon meshes and it works just the way I asked.However, the issue I have is on solids/surfaces, so how can I use it here?The command seems only to work on 3d faces.

John Connor
23.02.2017, 14:52
I think this can be accomplished in Inventor.  Search on "reverse normal direction of translated face or body" for further information.

23.02.2017, 15:37
[QUOTE=John Connor]I think this can be accomplished in Inventor.  Search on "reverse normal direction of translated face or body" for further information.[/QUOTE]
Thanks. We don't have Inventor at the office just now, but maybe at some point. If it opens and saves DWG natively, this would be a acceptable detour to fix and then save and continue in AutoCAD. Otherwise, I could as well use 3dsMax to fix the normals, and re-export.But I'll wait to hear if someone hopefully knows an AutoCAD way for solids/surfaces similar to the first suggestion that was for 3d faces.

Vladimir Michl
24.02.2017, 09:11

You can explode more complex objects to 3D faces.

24.02.2017, 10:41
[QUOTE=Vladimir Michl] You can explode more complex objects to 3D faces.[/QUOTE]Please have a look at this DWG don't know how to attach - if someone would please tell me how, I can attach the file here for future reference)Colors:Green: Regular surfaces.Yellow: When I exploded the surfaces, they turned into regions, not 3d faces.Red: The problematic surfaces, ie need their faces to be flipped. I can see that the faces are flipped when I export this to 3dsMax.See if it works for you and thank you in advance.

02.03.2017, 14:09
Did anyone have the time to check the attached file?I didn't manage to explode to a 3D face, it rather turned into something else.

26.08.2017, 23:05
In case anyone else stumbles into this matter, I solved it by rebuilding the surfaces.Planar surface can be exploded and output lines. A surface can be built from them with SURFNETWORK.After exploding the rounded corner, it can be rebuild with Loft with Guide Curves.If we wanted a command similar to Rhinos FLIP, I think it has to be programmed in .NET or similar.

philippe JOSEPH
27.08.2017, 21:07
Hello HaiderOfSweden, why can't you render ( and other things ) directly with AutoCAD ?You can render anyway with simple colors even  if you don't affect a material to your solids.If you affect a material it can be smarter...
philippe JOSEPH2017-08-27 21:07:51

27.08.2017, 21:58
Hello Philippe!I render photorealistic stuff out of my AutoCAD models.The DWG you saw previously is the part to the right.You might wonder why I bother with this question if the surfaces are going to end up in 3dsMax anyway where I could flip the normals. But yet, I want to model a fault free model in AutoCAD so that I won't need to do extra adjustments afterwards in 3dsMax...

philippe JOSEPH
28.08.2017, 07:16

Hello HaiderOfSweden, very , very nice result.

29.08.2017, 20:34
Thank you, Philippe :)