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Old 27th July 2006, 10:38 AM   #1
coldby
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Default Grouping criteria

When I export as an .obj a composite geometry from AC3D and reimport it into something else (say Bryce), sometimes the imported object can be ungrouped, but only to a limited extent . Does anyone know what defines the way individual components are chosen? Group? Texture? Colour? Object? Smell?
I run some hasty tests but got seemengly contradictory results - or maybe it could have been the 95 °F in my office
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Old 27th July 2006, 07:38 PM   #2
Dennis
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Default Re: Grouping criteria

If the "OBJ write groups" option is checked in your AC3D settings (under "Files"), the OBJ exporter will export using your AC3D groups. Ungrouped objects all go into a single group.

If the option is unchecked, everything goes into one group.

Note that the OBJ importer for AC3D does not read data back into groups at this time.

Of the apps I've personally tested this against:

* Ultimate Unwrap 3D and trueSpace/luuv both read the group info consistently/correctly.

* LightWave, Vue, and Poser all push the group geometry into a single object on import, so they're no help for making sure groups are getting done correctly.

I haven't used Bryce, so couldn't speak to how it's handling the groupings, whether it's deciding on its own groupings based on various object attributes or whether it's actually trying to use the OBJ groups...

Post back if you're still seeing issues,

HTH

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Old 31st July 2006, 08:51 AM   #3
coldby
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Default some more light

Hi Dennis, thanks for your clarification.
Unfortunately some brief further tests made it evident that Bryce doesn't care a damn about the way objects are grouped within an .obj file, and prefers to use its own criteria. Funny as it may look, the only criterion I could identify so far was the colour: equally coloured surfaces, no matter what object or group they initially belonged to, constitute one single Bryce object. I haven't had time yet to check if 'the same texture' is a similar criterion - might as well be.

Thus, to Bryce users: should 16 groups (the 16 colours available in AC3D) be too few it could be advisable to export individual objects as separate files and then re-assemble and re-group them in Bryce after texturing.
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Old 31st July 2006, 02:14 PM   #4
luuckyy
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Default Re: some more light

Coldby, maybe Bryce groups your objects by material then, and not by colour as you said.
You can have several materials with the same colour in AC3D.
And you also can have more than 16 materials in AC3D by right clicking on one of them and selecting "append new material".
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Old 1st August 2006, 10:59 AM   #5
coldby
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Default Re: Grouping criteria

Thank you luuckyy, I think you might be right. And reckon with finding it out for sure at the first available moment after the work stops gnawing at my heels
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