Add documentation for geometry resources

[redartengineer]

Adds a README to the Geometry resources folder documenting the sphere, cube, Shader Ball, and Boombox as well as Chess Set, Cloth, Plane, and Teapot.
Referencing #2343.

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: redartengineer / name: kgdesigncode (abbdcff)

[jstone-lucasfilm]

Welcome, @redartengineer, and thanks for this contribution! From an initial review, most of these details look accurate to me, though I'd note a few areas for improvement:

1. For the Boombox, I'd suggest crediting the original source alongside its contributor. The model is the BoomBox sample from the Khronos glTF-Sample-Assets repository, created and donated by Microsoft under a CC0 license, and it was contributed to MaterialX by Ed Mackey in Add glTF BoomBox example #870.
2. For the Chess Set, the header of standard_surface_chess_set.mtlx credits Side Effects for contributing the geometry and materials, with the artwork by Moeen Sayed and Mujtaba Sayed, so I'd suggest carrying the Side Effects credit into the README as well.
3. Since shaderball_ao.png is the one file in this folder that the README doesn't yet cover, it may be worth a sentence in the Shader Ball section, noting that this is the pre-baked ambient occlusion map that MaterialXView pairs with the shader ball geometry.

A few smaller notes:

• The section heading "Shaderball" and the prose "Shader Ball" could be unified, and I'd lean towards "Shader Ball" for both.
• It may be worth linking each historical note to its originating pull request (e.g. ShaderX to MaterialX merge #187 for the Shader Ball, Fix to OBJ geometry: sphere and plane #819 for the plane update, Chess set example #982 for the Chess Set), so that readers can trace the full story of each asset.
• Since readers might otherwise assume a single quad, it's worth mentioning that the plane is a subdivided 30x30 grid, making it usable for per-vertex effects such as displacement.

Overall this looks like a great first contribution, and with a few refinements it should be ready to merge.

[redartengineer]

@jstone-lucasfilm Thanks for the feedback! I've updated the README with the provided feedback by including the intended credits and contributors. I also added additional information for the other geometries.
Any other feedback I can apply as well!

[jstone-lucasfilm]

Thanks for the updates, @redartengineer! The new credits and PR links look great, and the README is very close to ready. Two corrections that I'd consider important before we merge:

1. In the Teapot section, teapot.obj was actually added in ShaderX to MaterialX merge #187 alongside the sphere, plane, and original shader ball. It was Merge of MaterialXRender and MaterialXView to ILM #198 that introduced MaterialXView with the teapot as its default mesh, and Render and Viewer updates #215 that switched that default to the Shader Ball. Since the rest of the README works at the level of years, I'd suggest dropping the day-level dates here as well.
2. In the Cube section, I'd suggest describing cube.obj as "a unit cube centered at the origin", stating its dimensions in units as we do for the sphere and plane. It may also be worth pointing readers to resources/Materials/TestSuite/stdlib/texture/udim.mtlx, which is the UDIM test material that pairs with this geometry.

Two optional refinements, which you're welcome to include or leave for follow-up:

• The Shader Ball GLB contains two meshes, Preview_Mesh and Calibration_Mesh, which the example looks assign materials to.
• The plane lies in the XY plane facing +Z, which is useful context for anyone testing displacement.

Does that sound reasonable to you?

[redartengineer]

@jstone-lucasfilm No problem, I will apply the new feedback!