Materials on skinned meshes

A rigged character usually has several materials: skin, cloth, armour, hair, each with its own textures. A Skinned Mesh Renderer draws such a model in parts, one per material in the file, each with that material.

What a model gets by itself

When a rigged .glb / .gltf has more than one material, or any textures, each part is drawn with the material saved in the file:

Parts are smooth-shaded (the file’s normals are used). The textures are named after the model, Models/hero.glb#image2, so a .tmat can name them too.

A model with one plain material and no textures is one mesh drawn with its Mesh Renderer’s settings (colour, metallic, roughness, texture), exactly as before.

Your own materials

The Inspector lists the parts under the Skinned Mesh Renderer, by the file’s material names. Type a .tmat path beside a part to draw it with that material instead; leave it empty for the file’s own. Precedence, highest first:

1. the part’s own .tmat;
2. a Material on the Mesh Renderer on the same object, which covers every part that has none of its own (so a scene that gave a skinned model one material still looks the same);
3. the material saved in the file.

The Mesh Renderer’s Color still tints every part.

From code:

let skinned = GetComponent<SkinnedMeshRenderer>();
for (int i < skinned.PartCount)
    Log.Info(skinned.PartName(i));
skinned.SetPartMaterial(1, "Materials/armour_damaged.tmat");   // "" gives the part back the file's material

The choices are saved with the scene in the component’s materials field, Skin=Materials/skin.tmat;Armour=....

Hiding and dyeing parts

A character customizer can put every choice in one model (each hat, hairstyle and coat a part of its own, by material
name) and pick what is shown and in what colours, so one skeleton animates them all:

skinned.SetPartHidden("Hat_Tricorn", true);              // Hidden Parts: not drawn, no shadow
skinned.SetPartColor("Coat", .(0.56f, 0.14f, 0.16f));    // Part Colors: multiplies the part's material colour
skinned.SetPartShadowOnly("Head", true);                 // Shadow Only Parts: a first-person player's own head

They are three fields, saved with the scene: hiddenParts and shadowOnlyParts (part names separated by ;) and
partColors (Coat=0.56 0.14 0.16;Hair=0.2 0.15 0.1). Set the strings directly to change many parts at once; they are
applied on the next frame. On a Mesh Renderer, MeshRenderer.Part has the same three settings (hidden, tint,
shadowOnly) for any component that hands it parts.

Networking

SetPartMaterial, called on the server or on the machine of the player who owns the object, is sent to every machine, the same way as MeshRenderer.SetMaterial. Materials chosen in the editor are part of the scene and need nothing sent.

How it is drawn

The model’s vertices are skinned once a frame into one buffer; each part is a mesh with indices of its own that draws those vertices (Mesh.VertexSource), so several materials cost no extra skinning or upload. MeshRenderer.RuntimeParts is the general form: any component can hand a renderer a list of meshes, each with a material, to draw in place of its one mesh.

Tests