examples: add an Lattice Boltzmann Method simulation

[Bruno-Vdr]

Added into SDL examples a basic lattice boltzmann method that simulates fluids flow.

[JalonSolov]

Need to run v fmt -w . in your repo, then commit the changes. That should fix the CI errors.

[Bruno-Vdr]

It's done. I'm not used to these modern workflow. I don't know if I'm supposed to close this PR and create a new one.
Regards

[spytheman]

No, the PR is fine - the formatting changes are visible now.

[JalonSolov]

Something weird in the CI here... it is trying to compile each of the lbm files separately, instead of as a single program.

[larpon]

That is odd, I can't spot any immediate reasons for it to do so - other examples are also multiple files in a sub-directory

[JalonSolov]

Hmm... the other examples only have a single .v file, though. Shader files, etc, but only 1 .v file.

[JalonSolov]

Is v should-compile-all sdl/examples/ treating them as separate files?

[JalonSolov]

Yeah, that's it. From it's help:

Usage:
v should-compile-all [-c] examples/ some/deep/file.v another/
... will try to compile all .v files found in the given folders and files, one by one.
If every single one of them compiles, the command will exit with an error code of 0.
If any of them fail to compile, the command will exit with an error code of 1.

[JalonSolov]

Since this is the first example with multiple .v files that go together, it's the first time it has been a problem.

[larpon]

You are right. I misremembered completely, my bad.

[spytheman]

v should-compile-all ~/.vmodules/sdl/examples/ should work now with latest V.

./v should-compile-all examples/ (in the main V repo) also works 🥳 - the tool detects projects with v.mod files, and compiles them as a whole now, not file by file.

[JalonSolov]

Problem with os.glob() now?

[spytheman]

Yes, os.glob is a mess on windows. I think we should just use the unix implementation there too, but that will take time :-| .

For now, I just used os.walk_ext/2 instead.

[spytheman]

The only remaining failure is also not related to the PR ...
We should update the macos runner name, since macos-12 was deprecated.

[larpon]

I have reduced the sizes of the png files by ~94 to ~98% and removed the empty/unneeded .gitignore in examples/lbm/.gitignore.

@spytheman I think it is good to go into master I'll make sure to propagate the changes to all the other branches when this is merged

[spytheman]

Everything seems fine now, merging.