Some python error stack trace when tried to use it.

[dancovich]

Some python error stack trace when tried to use it.

[Dancovich]

You placed it in the right folder. It seems there is an import error in the JSON exporting script I use. I'll do some testing in Blender 2.77 and report back. Thanks for the report.

[Dancovich]

Sorry for taking so long to respond. I tested this on Blender 2.77 and 2.78 in Ubuntu Linux 16.04 and this error didn't occur.

The import error (cannot import name 'FLOAT_REPR') is being given to a Python library, this constant should be present on the "json" module which is part of Python.

I don't know why your combination of Blender and Manjaro Linux is giving this error, as far as I know Blender searches for it's own bundled Python library before using the system library but your error might be coming from Blender using Manjaro's Python and not finding this particular constant declared in the json module.

If you're still having this issue (or even using my library at all) in Blender 2.78 try making sure you're using the bundled Python in Blender.

[stewlab]

I am having the same problem in Blender 2.76 on Ubuntu 16.04:

Problem Source

It looks like 'FLOAT_REPR' was removed from json.encoder in the transition from Python 3.5.1 to 3.5.2, according to the following diff:
https://fossies.org/diffs/Python/3.5.1_vs_3.5.2/Lib/json/encoder.py-diff.html

Blender 2.76 seems to default to Python 3.5.2, which is probably why some of us are getting this issue.

Temporary Solution (not really reccomended)

I was able to get around the issue by opening the Python console in Blender (Shift + F4), and manually setting the 'FLOAT_REPR' value by entering the following in the console:
import json
json.encoder.FLOAT_REPR = float.__repr__

I was then able to enable and use the g3d exporter plugin in the user preferences without any error. However, the steps in this method need to be repeated every time you restart Blender.

Permanent Solution

I was able to fix this permanently by modifying g3dj_json_encoder.py in the main io_scene_g3d plugin directory.

The problem is the following line in that file does not work in Python 3.5.2 (around line 20):
from json.encoder import encode_basestring_ascii, encode_basestring, FLOAT_REPR, INFINITY

So I just changed it to the following:
from json.encoder import encode_basestring_ascii, encode_basestring, INFINITY

Also, I needed to change the FLOAT_REPR usage (around line 63):
from
_repr=FLOAT_REPR

to
_repr=float.__repr__

I then saved the file, restarted Blender, enabled the plugin, and it worked as intended. I have not tested this with Python versions lower than 3.5.2, but I will submit a pull request once I verify that it works with versions below that.

Edit: merge request #10 submitted, as this code looks to work with Python 2.7. The recent Blender versions seem to support Python 3+, so this should be fine.

[Dancovich]

I'll just do some final testing but it seems you where on point on the cause. I'll accept the pull request after this final test.

Thanks for contributing.

[SolarLune]

Hello! I'm looking into using this exporter, but I stumbled on this same bug. Is the PR being held up for some reason?

[Dancovich]

@SolarLune, I swear I though it was already merged as it was already tested.

Done now, it should work. Please report if it's still giving an error.

[SolarLune]

Hey, that solved it. Thanks!