Reversed normals on export

**Professor420** · 11-16-2005, 00:30

This is the second time this has happened to me. When I export a unit, the normals of an element (not neccessarily the entire object) become flipped. The models works fine in 3dstudio, but when I import it or put it ingame, the normals flip. I can pre-flip the normals, but that makes it tedious if I want to work on the .max file. Any ideas?

**Bwian** · 11-16-2005, 09:29

This is a wierd one ....

I am assuming you haven't got the material set to double sided in Max ... sounds obvious, but I have caught myself out doing that before. THe normals may be inverted and you can't see it

Also...you don't say if this is a scratch built model or a modification of something someone else built. The problem may not be yours, so to speak!

Does Max have a 'show normals' kind of option? Never spotted one, but I could trawl the building sized manual and see if one exists

**Professor420** · 11-17-2005, 08:08

No, my materials aren't double sided, the normals are fine on the original model, they flip on export. I wish I could find a common trend of whats causing it, but no dice. I've done completely custom meshes that have come out fine, I've been working in 3ds and Maya for a long time, my geometry does not have any problems with it. I am almost sure it is a bug with the exporter, since this particular instance happened when I did modifications to a helmet that worked fine before, then upon export, the helmet's normals were flipped (the entire object, not just an element like I had said earler). I had to end up importing a working version (which I could also have done by pre-flipping, exporting, and then importing). There is some aspect to my geometry, some sort of hidden property, that is causing the exporter to malfunction. With we had Verctingorix to figure it out.

**hoggy** · 11-17-2005, 10:14

a few things can cause this, Max's mirror tool can cause reversed normals when you reset transforms etc.

In an object's properies set backface cull to on. or do quick renders in Max to check but turn 'force 2 sided off' to view flipped normals in Max

show normals is in the options on the right in poly mode
'flip' is also there and will flip the normals of selected polys.

**Bwian** · 11-17-2005, 10:40

Wierd... it is always possible that you are using tools to model with that Vercingetorix didn't allow for in the exporter.

I only really use Max for teh riging and final export, but do all the modelling and skinning in Lightwave. The conversion process through 3Ds squashes anything, and I have not had any problems.

If you want, you could send me the mesh and I can run it through and see if it exports OK for me. I have Max 6.

That would rule out any corruption of the script etc.

**Professor420** · 11-18-2005, 01:31

As I said, its nothing to do with the geometry of the model. I will try exporting and importing as an .obj though if it comes up again.
I do most of my RTW modelling in max, if I build a mesh from scratch I use Maya (I enjoy its modelling tools much more, I'd say I like it overall more than max except for its abhorrent lighting).

**Vercingetorix** · 11-18-2005, 05:35

This is something I have come across several times. The root the problem has to do with the translation from right-handed to left-handed coordinate systems. I've noticed this happening more often when I mirror a piece of geometry, but I've also had it happen when I haven't done any mirroring. The solution is typically just to apply the normal modifier and click 'flip normals'. It's not the best way, but I've yet to figure out how these misbehaving normals can be corrected otherwise. So it is a bug in the exporter, it's never been a high priority to fix because it is somewhat rare and the solution isn't obvious (I have tinkered with it in the past but to no avail.)

**Bwian** · 11-18-2005, 10:02

Thanks for clearing that one up Vercingetorix :D It's never happened to me...but then I am converting to 3DS using Deep Exploration, and I think that pretty much destroys any fancy formatting. 3DS may be primitive..but it has it's uses.

On a completely different tack... Prof...how easy was Maya to pick up? I looked at it briefly when I was making stuff for UT2004 ( ships with a limited version of Maya ) but never really got into it. ActorX for Max worked fine, so I never troubled to learn another tool.