How to modify UV coordinates in morphing animation

[archefox]

When I morph a model, how to modify UV coordinates in animation. The surface area is changed in animation. So I must modify UV coordinates. But it can only change vertex position and normal data.

[Dark_Photon]

As with position and normal, pass both texcoords into the vertex shader, and interpolate them.

[Dark_Photon]

To glTF specifically…

I don’t see anything here precluding texcoords. Just that support for it is optional:

• glTF 2.0 Spec : Section 3.7.2.2. Morph Targets

Client implementations SHOULD support at least three attributes — POSITION, NORMAL, and TANGENT — for morphing. Client implementations MAY optionally support morphed TEXCOORD_n and/or COLOR_n attributes.
…
Accessor type and component type for each morphed attribute semantic property MUST follow the table below.
…

Name	Accessor Type(s)	Component Type(s)	Description
TEXCOORD_n	VEC2	float signed byte normalized signed short normalized unsigned byte normalized unsigned short normalized	ST texture coordinate displacements

[archefox]

Does three.js support TEXCOORD_n attribute in the targets property defined in the Mesh primitives ?

[Dark_Photon]

You may want to ask the guys that maintain it. A few related links on this I found to get you started:

• Add support for TEXCOORD_n and COLOR_n for morph targets · Issue #23467 · mrdoob/three.js · GitHub
• Added support for COLOR_n and TEXCOORD_n in morph targets - #116 - vpenades/SharpGLTF - Github
• three.js webgl - morph targets - face

The latter suggests maybe yes (?) But the first makes me wonder.

[archefox]

Oh, I know. Thank you! Because I use tinygltf. But it not support TEXCOORD_n in targets.