Armatures and Skinning

Armatures and Skinning

Important

Two things decide whether a character works at all: its mesh has to be called base, and its armature has to stand at hip height, held in the armature's Delta Transform. The game's animations move the body through the frame of that name and only turn the joints. Get either wrong and the limbs bend while the body stays standing through a crouch or a roll, or the whole character floats.

1. The skeleton

Add ▸ 4DS ▸ Character Skeleton builds Tommy's: eighteen joints in the order the game numbers them, standing at the default mesh origin, with the character's usual extra frames — notify for animation cues, gun1, gun2, blnd and targetN.

Add ▸ 4DS ▸ Joint adds a single joint at the 3D cursor, on a new armature or the one you have.

2. The mesh

Name it base. Set Visual Type: Single Mesh — or Single Morph if it has shape keys. Parent it to the armature and give it an Armature modifier pointing at the same armature. Its own origin can be anywhere.

If the armature is not standing where it should, press Set Default Mesh Origin in the 4DS Model tab. It works the place out from the character's own skeleton — a little above the point midway between its l_thigh and r_thigh joints — so a character of another size stands at its own hip height, not Tommy's.

3. Weights, or influence boxes

The game plays vertex weights under two rules: at most two joints per vertex, and those two have to be a joint and its own parent. The export can correct both, and says what it changed.

Two ways to get there:

• Paint them yourself, one vertex group per joint. Painted weights are exported exactly as they are.
• Let the boxes make them. Every joint carries an influence box — a box across the limb saying which vertices it moves. A joint with no painted weights is written the weights its box makes. This is how the game's own models were built.

Working with the boxes

Tool	What it does
The handles, in Pose Mode	Six grey ones on the box's faces resize it, three arrows slide it, three rings turn it. Each kind keeps its own distance on screen, so a small box is still easy to hit.
Handles (4DS Model tab)	Narrows them to one kind: All, Resize, Move or Turn.
Fit Influence Box	Builds one the way the game's own sit: on the joint, aimed at the joint below it, reaching a fifth of the way there, as wide as the mesh around it.
Make Weights From Boxes	Paints what the export would make, so you can see it and change it. Pressing it changes nothing about what gets written.
Clear All Weights	Empties the groups and leaves their order alone, so the joints keep their numbering.
Influence Boxes, In Front, Joint Size	Viewport switches only — none of them change what is written.

The limits

• 64 joints below a skinned mesh. The game gathers no more. Its own characters use 25 at most.
• One skinned mesh per armature.
• A vertex the mesh keeps for itself holds its share in the vertex group the Armature modifier holds back, with Invert on.