Models for checking normal maps

[lexaknyazev]

We need sample models for these cases (+ versions of these with morph targets):

Normals	Tangents	Normal map	Engine's feature to check
❌	❌	❌	Flat normals generation
❌	❌	✔️	MikkTSpace implementation with generated normals
✔️	❌	✔️	MikkTSpace implementation with provided normals

@bghgary Is it something glTF-Asset-Generator could assist with?

[bghgary]

Ignoring morph targets for now, these should be tested by glTF-Asset-Generator but it doesn't right now. We will add them. Morph targets are later in the road map.

For now, I have a separate test that we use to test this in Babylon. You can find the assets here: https://github.com/BabylonJS/Website/tree/master/Assets/TestCube. Live view here: http://www.babylonjs.com/demos/gltfnormals/

[emackey]

I believe the original NormalTangentTest model handles the last case, as it tests the engine's ability to generate the tangent vectors. A later model was added, NormalTangentMirrorTest that tests the engine's ability to load supplied tangents, which turned out to be less well-supported than generating the tangents.

[DRx3D]

@lexaknyazev @bghgary @emackey : Is there a need to keep this open, or should it be transferred to glTF-Sample-Assets repo. Default is to close by 27 Nov.

[donmccurdy]

I don't know of an example for "MikkTSpace implementation with generated normals" yet. I think the rest of this is resolved.

[lexaknyazev]

This should be transferred.

[echadwick-artist]

PR #88 might help here, as it represents the common workflow of baking normals from a high-resolution model down into a low-resolution model.

However it does not contain tangent data. Should it?

[donmccurdy]

I'd lean toward including the tangents — one less thing a tester needs to worry about, and we have other assets geared specifically toward testing correct handling of missing tangents.