blender: add shim script for CLI use

[psibre]

• allows blender installed with cask to be used in external toolchains
• simply adding binary 'blender-#{version}-OSX_10.6-x86_64/blender.app/Contents/MacOS/blender' is insufficient, since blender needs a custom PYTHONPATH pointing to its bundled python library
• wrapper shim script is generated during preflight, then linked with binary

[psibre]

supersedes #9101

[psibre]

shim script could be tested upon installation, e.g.,

  # verify binary
  postflight do
    require 'tempfile'
    tempfile = Tempfile.new('tmp.py')
    tempfile.write 'import bpy\nprint(bpy.app.version_string)'
    cmd = "blender --background --python #{tempfile.path}"
    raise "Cannot run command `#{cmd}`" unless system cmd
  end

but did not stage that hunk, pending a proper solution (see #18830)

[vitorgalvao]

Should be target: 'blender' instead.

[psibre]

OK, commits are piling up. I'll be happy to squash if and when it's acceptable... =)

[vitorgalvao]

It should be "$@" (quoted as it is), here. Using $* will break in many cases (see differences).

[psibre]

indeed, thanks for the hint!

[vitorgalvao]

After this change, guess you can squash.

[psibre]

OK, I just replaced all the incremental commits by a single new one.

[vitorgalvao]

Just realised something. Travis will break here for sure (wrong stanza order).

Instead of

app
app

shimscript

preflight

binary

try

app
app
shimscript
binary

preflight

And run brew cask style {{your_cask}} after (if there are problems, it’ll find them).

[psibre]

Thanks, I did notice all the CI failures and was wondering what was going on!

[psibre]

but I don't understand the failures on travis...

[vitorgalvao]

I’ve seen this Travis hanging before, in otherwise correct changes (like #18879). Can you shed some light, @jawshooah?

[vitorgalvao]

Mind changing it for consistency?

[psibre]

you mean actually inserting the full URL of #18809?

[psibre]

never mind, already fixed in 40754ec. Thanks @adidalal !

[adidalal]

Thank you for the contribution. It needed some fixes, so they were made in 40754ec. Your contribution is still included (and still credited to you), with the appropriate modifications. Please feel free to ask about any of the changes.