Model Clean‐up
When you first import model into 3D software out first hurdle will be that for whatever reason its polygons will be split, that is not connected when they seemingly should be. You can usually check which parts are connected to each other by pressing Ctrl+L in Blender (Select > Select Linked)
Pic. Only this part is continuous
And a fix for that is a simple merge. Select All (Hotkey: A) and Merge By Distance (Hotkey: M) or Mesh > Merge > By Distance
But don't do that just yet because...
Polygons oftentimes not only split by also overlapping with their backface, usually on belts, ribbons etc. To visualize that go to Viewport Overlays settings and temporarily enable Face Orientations checkbox
A face normal is a theoretical line, perpendicular to the surface of a polygon. In 3D graphics normals are used to determine the orientation of a polygon face. Game engine then can opt not to draw backfaces, it's called backface culling.
You'll see all polygons change their colors into blue/red/purple-or-pink.
Blue - Forward facing polygons (relative to the camera)
Red - Backface
Purple/Pink - Overlapping polygons, one forward and one backward facing.
To flip a polygon, select it and press Alt+N > Flip or (Mesh > Normals > Flip)
Ok why do they even exist? For the record, it's possible to just turn on rendering faces from both sides in material settings in XIV, but game models typically use these actual overlapping flipped faces instead to paint the underside with a darker color and to have manual control over it I assume.
So how do they paint it a darker color? Let's see, turn off Face orientations and switch Blender to Vertex Paint mode.
Pic. Backfaces are painted yellow
I don't know how it works exactly, but things that are vertex painted yellow will appear darker in-game.
So make a mental note of where your double-sided overlapping faces were, or better yet keep a backup of the original mesh to check back.
And now that you know about backfaces you see why if you'll just merge everything without a little prep you risk ending up with randomly facing polygons, some of them could be painted yellow, some not.
So what I recommend doing is removing backfaces while you're editing the model and restoring them when you're done. Restoring them is very simple, just select forward polygons, duplicate (Shift+D) and Flip (Alt+N>Flip).
Or you could just fix any merge issues (flip stray polys, paint everything back to white)
Ok, now that we dealt with backfaces we can finally MERGE
So you finally merged and now there's a bunch of shading issues on the model.
TLDR what to do:
- Clear Custom Split Normals Data
- Change Auto Smooth Degree to 120
- Select Edges you want to harden and press Edge > Mark Sharp (Hotkey: Ctrl+E). (Another step where having backup of the original will be useful)
To explain what we did more in-depth, shading is based on Vertex Normals, they determine the visual softness or hardness between polygon faces.
- Normally they're auto-computed and kept under the hood, but when we imported the model it contained specific data about where they should point.
And when that's the case then blender sticks to using that data instead of auto-computing. - Then we messed with it by merging
- So we delete that data, it's called Custom Split Normals Data. Blender goes back to auto-computing vertex normals.
- We raise the auto-smoothing threshold to avoid unnecessary hard edges (I think 180deg will be default behavior in blender 4.1)
- We then manually mark edges that should be hard
At least that's a way of dealing with it for gear.
When it comes to body parts it'll be very important to retain those original vertex normals at the seams or they will be noticeable in-game.
