blender: implement multi version, redux

[the-furry-hubofeverything]

Description of changes

Continuation of #257780, resolves #256845.

I rewrote it, hopefully its easier to understand this time.

An update script is not included, that will probably be in a future PR.

Sidenote regarding blender 3.3:

I'm not porting blender 3.3 to current nixpkgs. All the libraries are too new to compile 3.3 with, and it only supports until September so I don't think it's worth the effort. if anyone still wants it, I had to -

1. use "-DLIBDIR=/does-not-exist" to ignore the included lib files, or else it would complain about LLVM_VERSION being missing.
2. Reimplement embree 3.x (3.13.5 is the last nixpkgs version), as Blender 4.x takes embree 4.x instead of embree 3.x
3. Add an backport patch for ocio in intern/opencolorio/ocio_impl_glsl.cc to add dimensions to getTexture, since it is now mandatory in ocio 2.3.0.

Current hitch is that openusd doesn't have usd_mesh.Primvar any more. Unfortunately, with my current skills, it's not trivial to either have two versions of openusd or to patch out the problematic part.

attempted build log

/build/blender-3.3.18/source/blender/io/usd/intern/usd_writer_mesh.cc: In member function 'void blender::io::usd::USDGenericMeshWriter::write_uv_maps(const Mesh*, pxrInternal_v0_24__pxrReserved__::UsdGeomMesh)':  
/build/blender-3.3.18/source/blender/io/usd/intern/usd_writer_mesh.cc:121:54: error: 'class pxrInternal_v0_24__pxrReserved__::UsdGeomMesh' has no member named 'CreatePrimvar'  
121 | pxr::UsdGeomPrimvar uv_coords_primvar = usd_mesh.CreatePrimvar(  
| ^~~~~~~~~~~~~  
[ 50%] Building CXX object source/blender/blenlib/CMakeFiles/bf_blenlib.dir/intern/task_pool.cc.o  
[ 50%] Building C object source/blender/python/gpu/CMakeFiles/bf_python_gpu.dir/gpu_py_vertex_buffer.c.o  
make[2]: *** [source/blender/io/usd/CMakeFiles/bf_usd.dir/build.make:202: source/blender/io/usd/CMakeFiles/bf_usd.dir/intern/usd_writer_mesh.cc.o] Error 1  
make[2]: *** Waiting for unfinished jobs....  
lines 3725-3739/4378 86%

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 24.05 Release Notes (or backporting 23.05 and 23.11 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

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[ryan4yin]

Any updates here?

[the-furry-hubofeverything]

Any updates here?

Unfortunately it couldn't get much attention and I'm very burnt out. If anyone is willing, they have full permission to use my changes to start their own PR. I'll leave this open until such PR exists.