Separate C source into many translation units

[fwilliams]

Enables faster compilation and easier code readability

[liruilong940607]

LGTM! @vye16 will take a look as well.

[vye16]

Hey! I support splitting these up into separate files, it'll be much easier to extend in the future. I think it would also be nice to add some header files, maybe for fully_fused_projection and rasterize_to_pixels, but that can be in the future, since we don't currently have headers for those right now. Otherwise this looks great to me!

[yklcs]

Note that the default parallelism of Ninja uses num_cores + 2 parallel jobs which easily results in swapping/OoM.
I needed to set the MAX_JOBS environment variable to something more sane to get gsplat to compile with this PR merged.

[liruilong940607]

Note that the default parallelism of Ninja uses num_cores + 2 parallel jobs which easily results in swapping/OoM. I needed to set the MAX_JOBS environment variable to something more sane to get gsplat to compile with this PR merged.

Ah true. Do you know an elegant way to limit it in setup.py and JIT compiling at here?

gsplat/gsplat/cuda/_backend.py

Lines 67 to 75 in 2f0bb12

	# If the build exists, we assume the extension has been built
	# and we can load it.
	_C = load(
	name=name,
	sources=sources,
	extra_cflags=extra_cflags,
	extra_cuda_cflags=extra_cuda_cflags,
	extra_include_paths=extra_include_paths,
	)

Ideally we should set a default parallelism to a reasonable one (e.g., 12) but still allow user to overwrite that with MAX_JOBS.

cc @fwilliams