The coordinate system problem of blender to three.js

[iceleaf97]

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Description of the problem

In this three.js scene, I put my camera at (0, 0, 80) and put a directionalLight at ( 50, 50, 50 ). Then, I create a white sphere geometry (the left sphere) and load a json model from blender (the right sphere). However, the scene showed on the screen looks weird. The directional light project on the wrong surface of the json model. It seems the problem of the coordinate system.
two sphere

The version I use is that Blender v2.78 and three.js r80

Three.js version

• Dev
• r82
• r80

Browser

• All of them
• Chrome
• Firefox
• Internet Explorer

OS

• All of them
• Windows
• Linux
• Android
• IOS

Hardware Requirements (graphics card, VR Device, ...)

[Itee]

And what about three.js r82 ? Same problem ?

[michaelybecker]

Commenting here to say I've noticed similar behavior in specifically similar circumstances - namely upon importing a sphere from Blender and trying to illuminate it. Both DirectionalLight and PointLight yielded surprisingly counterintuitive and seemingly wrong results. I ended up working around the anomaly (code here, live here) but the issue is definitely there.

Hope someone has an illuminating thought about it.

[Itee]

I got an 404 error for second (live) link.
What is the sphere type ? Ico or UV ? Seems to be an UVSphere, right ?

And what about the blender export, as json object, right ? And did you try with an .obj export if you got the same behavior (this could be a work around waiting fix).

For me the first thing that came up, is flipped normal (means inside the sphère, so try to flit normal before exporting your json) and give me a feedback.

[iceleaf97]

Here are some test results:
blender version: v2.78a
three.js version: r82
exporter: io_three
sphere type: UVsphere
model filetype: .json

【io_three before version 76】
I got a correct result
version 76
version 75

【io_three "all versions" after 77 include 82】
I got the wrong result
version 77
version 82

[zydecode]

not sure if this is the same issue, but I solved similar to this by changing a line in one of the blender -> threejs exporter files: in exporter/api/mesh.py change line 619 from:
vector = (vector[0], vector[2], -vector[1])
to
vector = (vector[0], vector[1], vector[2])

[mrdoob]

@zydecode would you like to do a Pull Request with the fix?

[zydecode]

I'm happy to, as it immediately solved the issues we were having, and
we've had no more issues since implementing this fix.

I just hope that the vectors were not as they were to solve another issue..

Cheers,

Sean

On 11/16/2016 10:57 PM, Mr.doob wrote:

@zydecode https://github.com/zydecode would you like to do a Pull
Request with the fix?

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[iceleaf97]

@zydecode It does work! Thank you.

[mvangeest]

@iceleaf97 A pull request for this change was created (#10155) and has since been merged; if that fixes the problem, perhaps this issue can be closed?