Fix Blend Shapes and add Convert to Z Up option in Blender exporter

[dougppaz]

• Fix Blend Shapes in Blender Exporter
• Add Convert to Z Up option in Blender exporter
• Extra: Fix no action in animation curves (api/animation.py Blender Exporter)

[mrdoob]

When would Flip Axes need to be used, and when wouldn't?

[dougppaz]

I'm working on a project that receives animation information remotely. I found it to be more practical to use blender axes. I use in the same project, bones and blend shapes too.

[WestLangley]

Actually, axes are not "flipped" -- it is a coordinate system rotation of 90 degrees.

[dougppaz]

You right @WestLangley
What's the best nomenclature to this?

I think I'll create another pull request to correct the blend shape's error. And we come back to discuss this question here.

What do you think? @mrdoob @WestLangley

[WestLangley]

Sometimes the term z-up is used. /ping @Mugen87 ?

But someone other than myself will have to participate in this particular issue.

[Mugen87]

Unfortunately, i'm not familiar with Python and the Blender API.

@douglasppaz It is not the first time the project is faced with this issue. You might find some information in these threads: #11404 and #11540

[dougppaz]

I'll change to "Convert to Z Up" option. Okay?

@WestLangley @Mugen87 Thanks for supporting.

[dougppaz]

Done!

[mrdoob]

Lets try to solve #13130 first.

[Mugen87]

The JSON Blender exporter has been removed with R93 (#14117).