Maya: Flipping object makes strange normals!

martynball

Hey guys, unlike Max where there is a lovely Symmetry modifier, I found that the only way to mirror an object is to use Duplicate Special and put "-1" in the required axis.

Now after doing this I found that the normal's are obviously flipped, so I click the Reverse button under the Normals menu. Here is the result, still wrong normals!



Also, a second question but similar, if I want to model one half and duplicate the object so that I can see the other half update as I model one half, I have to put up with flipped normal's since I can't flip them as the duplicate is an instance, any work around!?

ZippZopp

i see you have the viewport ambient occlusion on. its actually pretty handy to have on because it actually tells you if your normals are flipped or not. after duplicating and scaling -1, try freezing your transforms. maya should now correct the normals on negatively scaled geometry when the normals are frozen.

your second question is something that showed up on my computer a while back and it was agitating because it looked like they had broken something. i just tried it again though and I have no issues in maya 2015 with it. i'm running 2015 sp5 though so maybe it was fixed there. what version are you on?

ASTUS

What I tend to do is this.

Ctrl+G - Group the object
Holding the "D" Key change the pivot point to where you need it.
Then in the Attribute editor on the right hand side change your desired scale value to "-1"
Then select the object and "Ctrl+p" To un-parent the object from the group.

What you are essentially doing is attaching the GEO to a NULL (Grouping), negatively scaling the null (-1 in Scale x,y or z), and then pulling the GEO out of the NULL (Ctrl+P Un-parenting) once in the desired state out of the null.

This way you never have problems at render time with flipped normal's.

Enjoy!

MethodJ

Maya does have a Mirror Geometry tool somewhere. I prefer duping with negative scale.

An easy, dirty fix for the flipped normals is to go to the viewprt Lighting menu, and turn 2 Sided Lighting on.