FBX import - Face flipping

[TimD]

FBX import - Face flipping

Hi --

And a Happy new year to you all...

I'm having problems with normals flipping when I import via FBX (see below).

I don't know if the problem is from SketchUp or the Cheetah loader... it seems to have started spontaneously.

I know I can flip normals to fix this...

A related request -- would it be possible to write a 'Force Normals' routine, to flip normals to the majority orientation? This would sort this out in one go...

 

[Eric_J]

Hi Tim

I'm not sure this will help, but.....

Have you run "Fix Non-planer Faces" in SketchUp before exporting?

Are the planes oriented correctly in SketchUp?

I also found that reducing the number of groups and nested groups in SU (if you have any) helped. For example, in SU it's possible to have three of a polygon's edges in one group and the other edge and surface in another--by accident, of course--and I think that isn't happy-making during export/import....Exploding the group beforehand fixes that.

I'm still using 4.0, so I haven't done much FBX exporting, either...

Eric

 

[TimD]

Eric --
Where do I find 'Fix non-Planar Faces'? in SU?

My models are always completely ungrouped, then re-grouped according to material before I export.

Cheers,

Tim

 

[Eric_J]

OT--SketchUp

Eric --
Where do I find 'Fix non-Planar Faces'? in SU?

Umm...er...an excellent question! It was under Tools>Utilities, but it looks like that was dropped from v.5. OTOH, in v.5, under Window>Model Info>Statistics, there is something called "Fix Problems" (!), and there is something similar in Preferences>General--although the buttons and check boxes may just be placebos.....

Sorry...

Eric

 

[Martin]

Hi Tim,
Cheetah3D doesn't perform any polygon flipping during the import. So I guess the polygon is already flipped in the FBX file.

Automatic correction of flipped polygons isn't that 100% secure. Imagine a quad which consisting of two triangles of the same size. One is flipped.

In general the rendere doesn't care if a polygon is flipped. It makes only a difference if you use transparent materials with a refractive index unequal one. Since Cheetah3D uses the normal of a polygon to determine if it enters a glassy object or if it leaves it.

By,
Martin