Replacing body parts with gear vs. putting gear on top of body parts

The way SWTOR handles the clothes of our player characters and several of the NPCs is by swapping their naked or underwear-using body parts with their clothed counterparts.

This is so even when a character is showing skin while wearing some skimpy piece of armor: the skin is part of the armor piece's meshes, too. It simply happens that the armor piece, say, an Unfettered Trench Coat, instead of a single material uses two: the armor's material proper, and the character's naked skin one, each assigned to different regions of the mesh (typically, those material assignments match sets of whole polygons, which is very helpful if we'd need to separate the armor and skin areas into different objects).

So, if we just want to replicate the game's characters, using the game's method is more than enough. But if we want to reach beyond that and go full-on Barbie & Ken (deeper implications very much intended), we need to be able to put the gear on top of the body parts. That presents a few complications, which are very easily solvable.

The possibilities?

• Creating a T-shirt or a tank top by deleting a chest piece's sleeves' polygons.
• Lowering that leg piece's waistline by deleting or deforming the polygons at its top.
• Midriffing a jacket by doing the same to its bottom polys.
• Accentuating a cleavage by deleting a chest piece's bare skin polys and letting the naked body part show (their shapes are actually different).
• Sexier underwear.
• Doing fairly minimal use of Sculpting Mode tools (pull and push, mostly) to pose wind-blown jackets and coats, make room for hair in hoods, deform armor pieces, solve minor interpenetration issues, buff a character's muscles, etc.

Let's get started.

Body parts

A typical character is divided into the following parts (these are their internal names' prefixes):

• head_ (head to base of the neck, plus Twi'lek lekku and Nautolan tentacles).

• hair_ (hair, Togruta montrals, Zabrak horns, Twi'lek headbands).

• facehair_ (beards, Sith Pureblood and Rattataki jewelry, Miraluka masks, cyborg implants)

• chest_ (from base of neck to waist and wrists).

• hand_ (both hands as a single mesh).

• leg_ (waist to upper calves).

• boot_ (lower calves to feet, both pairs as a single mesh).

Typically, the hair is hidden when a hood comes up, and the head too when applying a fully covering helmet.

As for armor, a set has those same parts plus a few that actually get to sit on top of the rest:

• face_ (helmets, masks, googles, etc. Not hoods, though).
• chest_ (chest pieces plus hoods, capes, etc.).
• hand_ (gloves, vambraces, etc).
• bracer_ (wrist wraps, vambraces too, etc.).
• waist_ (belts, sashes, flaps, etc.).
• leg_ (pants, skirts, etc).
• boot_ (boots and the like).

The general idea is to keep a fully naked body (not showing underwear) and, instead of swapping, adding clothing/armor on top, slightly increasing the size of the pieces that intersect and/or are occluded by the naked body.

Wear no underwear

SWTOR's characters' underwear look uses legs and female chests parts with both bare skin and undergarment materials (which happen to be the same meshes used in the purchasable, dyeable Basic Women's Tank, Basic Women's Trunks and Basic Men's Trunks), and other "naked", skin-only parts:

Males:

• boot_naked_[bt]_archetype.gr2
• chest_naked_[bt]_archetype.gr2
• hand_naked_[bt]_archetype.gr2
• leg_underwear_[bt]_archetype.gr2 🔶

Females:

• boot_naked_[bt]_archetype.gr2
• chest_tightskin_[bt]_archetype.gr2 🔶
• hand_naked_[bt]_archetype.gr2
• leg_underwear_[bt]_archetype.gr2 🔶

([bt] is a body type code wildcard, to be replaced with bfa, bfn, etc.)

To be able to assemble fully naked bodies for both males and females we have two possibilities:

1. Use the underwear set of meshes and, in the parts with both skin and underwear material areas, assign the skin material to the underwear area. too.
2. Use _naked_ versions of all the body parts, instead:

• boot_naked_[bt]_archetype.gr2
• chest_naked_[bt]_archetype.gr2 🔶
• hand_naked_[bt]_archetype.gr2
• leg_naked_[bt]_archetype.gr2 🔶

Why the second option? One would think that there wouldn't be any difference between a chest_tightskin_[bt]_archetype.gr2 and a chest_naked_[bt]_archetype.gr2, mesh-wise, but in fact there is such: the cleavage of the latter is subtly deeper than the former's.

While at it: we would think, too, that the naked male chest and the portions shown in skin-exposing armor gear match each other. Again, it's not necessarily the case. So, just by using a complete set of naked body parts we get the sleekest versions of our characters' bodies which, combined with dresses or armor, will lead to more interesting interplay with lighting out of the different spacing between skin and cloth.

Keep body parts separate or fuse them?

When extracting SWTOR's 3D assets was done through Noesis, exporting them as .obj, recalculating the normals was a necessity, and usually resulted in very apparent seams (at the neck, wrists, waist, and ankles). Nowadays, the .gr2 importer add-on works so well that there's no seaming at all or is very negligible.

That said, we better join the body parts into a whole if we intend to apply additional processes that need to see the character's skin as a real continuum, such as when applying a Subdivision Surface Modifier to smooth out low poly areas, or if adding a Subsurface Scattering shader to the material to give the skin that extra certain something.

Also, remember to Merge by Distance before applying Modifiers to any object. We might not use them on the naked body parts, but some of the armor parts will most definitely need them, as we'll see later on.

Naked Materials

For the naked body parts we'll need the requisite materials and textures. Luckily, TORCommunity.com's Character Creator and its companion desktop app provide with them each time we export a character, no matter if they are in fully covering armor (unless that includes a full helmet, in which case we'll need to do a complementary helmet-less export).

Applying the materials is straightforward: the only difference between the naked meshes and the underwear ones is that the former have a single material slot (for a SkinB material) while the latter have two (Garment and SkinB).

(As expected, the results are very Barbie & Ken: neither modeled nor textured male or female genitalia, no pubic hair for the species that sport it, no female nipples or areolas. The infamous Nude Patch for SWTOR, a mod that modified some game data to swap armor parts with naked body ones, included retouched textures that tried to solve the latter with some success)

Binding for posing and animation.

Binding both our character's body and their armor to a skeleton at once is not problem at all. We can simply select all body and armor parts at once and parent them to the skeleton. It'll just work.

Remember: parenting to a skeleton it's not an irreversible process, so, we can do it all at once, or some parts now and others later. Same with unparenting.

Z-Fighting.

This is the real major gotcha, but it's not only easily solvable but a chance at beginning to improve our characters' looks and start playing with the process.

When first assembling our characters' bodies and armor at once, as soon as we start seeing them with rendered textures, especially through Eevee, we'll notice that the materials artifact badly the more body-hugging the armor or clothes are.

That's due to a phenomenon known as Z-Fighting. Basically, many armor pieces have objects whose polygons perfectly match the ones in the character's body parts (sometimes they both happen to use the same object asset, actually!). When that happens, the renderer is unable to know which one is in front and which one is meant to be left occluded. The result is a fringing, chattering mess, specially visible when turning around the models with the camera.

We need to do something to separate the conflicting polygons. An obvious solution would be to slightly scale up the coincident armor object, but that doesn't work too well, usually: the tools apply the scaling from the armor object's point of origin, usually displacing the polygons in inadequate directions. What we want is the polygons to move perpendicular to their faces, that is, in the direction of their normals.

There is a couple of far better ways to do it, though: through Blender's Modifiers!

(The biggest advantages of using Modifiers is that they are non-destructive: they don't alter the object's original mesh, so we can always revert to it; and that they have settings we can play with until we are satisfied with the results… or revisit them later on. What's more, we can purposely alter the original mesh and see the results cascade through the Modifiers we had applied to it)

Applying a Displace Modifier:

The Displace Modifier, by default, uses the object's normals as the direction in which to displace its polygons. As for the displacement value, usually something as low as 0.0005 suffices (Blender might show it rounded to 0.001 but on editing the field it'll respect the extra precision). If we see that there are bits where the body intersects the armor, we can try increasing it a little. If we see that we are needing to increase it so much that the armor feels a little too big, it might be better to go back to a reasonable value and correct the trouble spots in the Sculpting Mode with a touch of its Pull tool.

Normally, the gap between the displaced armor or clothes and the skin will be hidden by other pieces such as belts, gloves, neck pieces, etc. Still, if it becomes too apparent (maybe there is no other piece covering the hems), an alternative option is to use the Solidify Modifier.

Applying a Solidify Modifier:

The Solidify Modifier, instead of just displacing the polygons of the object in a direction, thickens them (it extrudes the object's surface). A Thickness of around 0.0005 to 0.001 seems to be typically enough. Then we have to play with the Offset value which tells the Modifier how far from the original position the thickened result has to be. It's the kind of parameters one usually adjusts by eyeballing it. Sometimes this Modifier produces a bit of shadowing weirdness in the solidified edges, in which case it's a matter of playing with the extra parameters to minimize it.

(Remember that the Offset's click'n'drag limits of -1 and +1 are "soft limits": we can input values past those by typing them into its value field)

Remember to apply Merge by Distance to the Modified items.

If we don't, we'll see artifacts the like of bits of the object flying away unconnected. If it happens because we forgot to do it, there's no need to backtrack: we can switch to Edit Mode, do the merging, and get back to Object Mode with the Modifiers still being applied.

Smoothing out the results with a Subdivision Surface Modifier.

SWTOR's character models have fairly low polygon density in general, even if it is higher in the face area. That leads to noticeable flat edged silhouettes and what some call "potato breasts". This is even more so in the case of armor gear.

The Subdivision Surface Modifier (or "SDS" Modifier) works quite well to solve this issue. Adding it to all the objects results in a far more pleasant look with just the default setting.

Some tips regarding its usage:

• This Modifier really requires that the character's body parts are joined into a single mesh object and its duplicate vertices are eliminated through a Merge by Distance operation, or they will artifact in very noticeable ways.

  The armor and clothes parts only need the Merge by Distance, though: artifacts out of seam issues are an oddity in their case. If they'd happen to appear, joining the troublesome parts might help (their modeling is a bit loose, so, no promises).

• As with any other Modifier, you can add, disable, or delete a SDS Modifier any time without altering the original model.

• The SDS process produces a tiny shrinkage in the models it is applied to (as they weren't built with SDS in mind). The really most noticeable effect is a slight, seductive 😏 parting of the lips that can be compensated through posing of the facial bones.

  Where the shrinkage could be a bit of a bother is in the case of Zabrak horns, as their sitting on top of the scalp isn't that terribly precise to begin with: the Subdivided head's shrinkage could produce a gap between the head and the horns' bases, visible from certain angles, that one would need to correct manually (moving some horns a little, etc.).

• Something to take into account when playing with Modifiers is that their stacking order can be changed any time. It's easy to have all objects in a character using an Armature Modifier (the result of parenting to an skeleton) plus a Displace or a Solidify one, plus a Subdivision Surface one. The stacking order can be changed at any time, which is something that might be interesting to experiment with to see which one gives best results.

• If applying some sculpting to the models, we have to take into account that we'll actually be working on the unsubdivided model, even if the Modifier shows us the subdivided results while we are sculpting. If we want to be able to sculpt the subdivided model because of the extra polygonal resolution, we can use the Multiresolution Modifier instead of the Subdivision Surface one.

The Multiresolution Modifier alternative (WIP).

A logical limitation of the Multiresolution Modifier (commonly known as "Multires" in the Blender community) is that the extra sculpting possibilities it offers requires it to be last in any stacking of Modifiers that affect the geometry of the object it's applied to.

Using Sculpt Mode while preserving reversibility (WIP).

Sculpt Mode comes in handy for both minor and major adjustments: from correcting a pesky interpenetration between the body and a piece of clothing where we'd rather don't displace or solidify the clothes any more (because they would like oversized) to making a cape flow dreamily as if facing the wind without caring for adding bones and making a simulation.

The use of Blender's Sculpt Mode implies making changes to the actual meshes, but those changes can be done in a manner so that they are both controllable and reversible at the touch of a slider.

Some "low-hanging fruit"-type examples (WIP):

Separating skin from clothes in revealing armor (WIP):

Trimming clothes by deleting edge polygons (WIP).