[x3d-public] Tests for Blender->X3D exporter utilizing texture transformation and per-vertex colors

[Michalis Kamburelis]

Vincent and all,

( Sorry it took me a while -- Christmas times are busy in offline
activities :) )

1. I prepared the promised tests of texture transformation in Blender,
to help implementing their handling in the Blender -> X3D exporter.

They are inside the "blender_tests/texture_transform/" of my
repository https://github.com/michaliskambi/x3d-tests/ . Browse them
through here https://github.com/michaliskambi/x3d-tests/tree/master/blender_tests/texture_transform
. To just download them, it's probably easiest to "git clone" the
whole x3d-tests repo.

The README inside (
https://github.com/michaliskambi/x3d-tests/blob/master/blender_tests/texture_transform/README.md
) already describes everything. A short summary:

- I tested transforming base, normal, metallic/roughness textures
(same or differently).

- I added a "real-life example" of using texture transformation (from
Castle Game Engine "examples/fps_game" demo,
https://github.com/castle-engine/castle-engine/tree/master/examples/fps_game
 ).

- I added glTF exporter outputs, screenshots from Blender, Castle
Model Viewer -> hopefully this all makes it clear what is the desired
output.

- TODO: I planned to do, but did not do this: I wanted to create a
"desired" X3D files, crafted by hand, to show how a proper X3D output
should look like. Not done yet, simply because of lack of time. I
don't want to keep you waiting, so I send you the tests as they are
now. Ping me if you think you need these "desired" X3D files :)

2. Moreover, I added tests for per-vertex colors.

This shows per-vertex colors generated using Blender's "Ambient
Occlusion" (make areas e.g. behind ears nicely darker even without
using real-time shadows) and how they can be multiplied with
material(s) in glTF. This is a feature we talked about -- you
mentioned you wanted to implement it by "premultiplying" the material
* per-vertex color. Hopefully my tests will help make sure it's all
correct :)

They are in:

https://github.com/michaliskambi/x3d-tests/tree/master/blender_tests/per_vertex_colors

Again, I added glTF exporter outputs, screenshots from Blender, Castle
Model Viewer -> showing what should happen.

I hope these are useful! Let me know if anything in this is unclear.

Regards,
Michalis