Add support to tessellate 'ngons with holes' in mesh's validate() func? Much useful for importers (FBX, OBJ...) #46761

New Issue

paul geraskin · 2015-11-13T16:25:21+01:00

paul geraskin commented

2015-11-13 16:25:21 +01:00

System Information

Blender Version
2.76

Short description of error
fbx does not import NGON. But it imports into Modo.
Blender:

Modo:

File:
exchange.fbx

Exact steps for others to reproduce the error
import fbx

**System Information** **Blender Version** 2.76 **Short description of error** fbx does not import NGON. But it imports into Modo. Blender: ![Selection_018.png](https://archive.blender.org/developer/F254290/Selection_018.png) Modo: ![Selection_020.png](https://archive.blender.org/developer/F254292/Selection_020.png) File: [exchange.fbx](https://archive.blender.org/developer/F254294/exchange.fbx) **Exact steps for others to reproduce the error** import fbx

paul geraskin commented

2015-11-13 16:25:21 +01:00

Changed status to: 'Open'

paul geraskin commented

2015-11-13 16:25:21 +01:00

Added subscriber: @PaulGeraskin

Bastien Montagne commented

2015-11-13 17:12:35 +01:00

Added subscribers: @ideasman42, @mont29

Bastien Montagne commented

2015-11-13 17:12:35 +01:00

Well… FBX does import ngons, the problem is that Blender does not supports ngons with holes (nor ngons using same edge more than once, which is how ngons with holes are represented in formats like FBX or OBJ).

OBJ importer does handle that situation, but the issue here is that doing the same thing with a format as complex as FBX is not really possible (would be a nightmare to correctly map newly generated geometry to old one for all the datalayers). It’s already really complex code in OBJ, btw.

Think the solution here would rather be to add an additional step to our (C-coded) mesh.validate() func, which would check for those blender-invalid specific cases and modify the geometry accordingly. Would also be much more efficient than doing this in py.

@ideasman42 if you agree, I can try to make a patch?

Well… FBX does import ngons, the problem is that Blender does not supports ngons with holes (nor ngons using same edge more than once, which is how ngons with holes are represented in formats like FBX or OBJ). OBJ importer does handle that situation, but the issue here is that doing the same thing with a format as complex as FBX is not really possible (would be a nightmare to correctly map newly generated geometry to old one for all the datalayers). It’s already really complex code in OBJ, btw. Think the solution here would rather be to add an additional step to our (C-coded) mesh.validate() func, which would check for those blender-invalid specific cases and modify the geometry accordingly. Would also be much more efficient than doing this in py. @ideasman42 if you agree, I can try to make a patch?

Bastien Montagne changed title from ~~FBX: fbx does not import NGON~~ to Add support to tessellate 'ngons with holes' in mesh's validate() func? Much useful for importers (FBX, OBJ...)

2015-11-13 17:15:27 +01:00

Bastien Montagne self-assigned this 2015-11-13 17:15:27 +01:00

Campbell Barton commented

2015-11-14 14:30:23 +01:00

@mont29, hi, yes - this can be added to validate. (port from OBJ's Python code).

However I'd like it to be optional, since this is an invalid face for Blender.

@mont29, hi, yes - this can be added to validate. (port from OBJ's Python code). However I'd like it to be optional, since this _is_ an invalid face for Blender.

Bastien Montagne commented

2015-11-14 14:31:27 +01:00

Yes of course, this has to be an option, we do not want that to validate internally-generated meshes ;)

Philipp Oeser removed the

Download

What's New

Blender Studio

Manual

Developers Blog

Documentation

Benchmark

Blender Conference

Development Fund

One-time Donations

Add support to tessellate 'ngons with holes' in mesh's validate() func? Much useful for importers (FBX, OBJ...) #46761