Backfaces

Definiton: In computer graphics, back-face culling determines whether a polygon of a graphical object is drawn.

FFXIV handles this in a few different ways, and how you use them is up to your own taste.

Basics

Opening up a model, you can go into Viewport Overlays > Face Orientation.

This will show you some colors, depending on what way the normals are facing.

Blue: Single mesh layer, outward facing.

Red: Single mesh layer, inward facing.

Purple: Double mesh layer, with red under and blue on top.

Pink: Double mesh layer, with blue under and red on top.

How does FFXIV render this in-game?

It depends on your material “Backfaces” option!

Show Backfaces:

• Will show ALL faces. That means blue, red, pink and purple will always be showing. 
• You do not want this if your mesh is pink and purple. It will look very funky because your normals will clip into each other.
• On a lot of meshes, blue and red will have slightly different looks. Generally you want anything that you see to be blue, because those are outwards facing normals.

Hide Backfaces:

• Will hide any inwards facing normals (backface culling). Red will be completely invisible, and pink/purple will look normal.
• Note - I generally do not notice any difference between pink or purple in-game, but perhaps it depends on what kind of material you’re working with, and if it has transparency or not. 

Which one do I use?

This also depends on how you want your material to render. 

Faces:

• Faces usually do not have any transparency, and you will be all good to just have a single layered mesh (blue & red). 
• Eyelashes/eyebrows are “hair” materials, so this is up to personal preference. I think that lashes tend to look a little less strong than I like with only a single face, so I like to double up on the faces, as I will explain below.

Hair & Gear:

• As mentioned above, you may want to double up on faces. You can try just blue/red on Show Backfaces, or doubling to pink/purple on Hide Backfaces, to see what you like better.
• Pros and Cons of each:
  • Show backfaces - lower poly count. Use if your mesh has no transparency.
  • Hide backfaces - doubles your poly count for whatever you’re duplicating, but your mesh may look better because it cares less about sunlight

How to double up on faces

(Personal preference) in edit mode, if your normals aren’t facing red, flip them to red by selecting all (press A) and doing Mesh > Normals > Flip

Select your object, then go to Modifier (bottom right). Add in a Solidify modifier, set Thickness to 0m and untick “Fill”.

This is all good for small meshes, but if you plan to ever edit a large mesh again or let other people edit it, you may want to duplicate your face as another object, so that it can be deleted easily.

Object Mode > Object > Duplicate

Edit Mode > A (select all) > Mesh > Normals > Flip

This will make the mesh look purple.