By casey
#182045
I've been working on this one for a week, and I finally got it.

The following two scene files are almost the same:

A: http://funkytroll.com/temp/matbug_indiv ... erials.mxs
B: http://funkytroll.com/temp/matbug_multi_material.mxs

They both contain only three things: a camera, an empty cubic room with a lambertian material, and a tetrahedral emitter.

Yet here is the image produced from rendering A after 20 minutes:

Image

And here is the image produced from rendering B after 20 minutes:

Image

There is only one difference between these two scenes: A has individual materials applied in MAX, whereas B uses a single multi-material in MAX whose two sub-materials are the two materials used individually by A. So in theory, they should have produced indentical MXSes. But as you can see, that is far from the case.

Cursorily, the MXS files that result look the same in Studio, but clearly there is something very important that is different. I, however, cannot seem to figure out what it is. I was able to isolate things down to such a simple situation, but without a better way to compare the MXS files, I can't tell what's different.

Furthermore, it is something very subtle in the MXS files, something that Studio somehow does not pay attention to, because - and here is the truly strange part - the bug only happens if you directly render those two MXS files. If you instead load them in Studio, and then render from Studio which forces a re-export of the MXS file to a temp one for rendering, they both render the same!

The secret thing that is different between them ceases to exist when the file is loaded into Studio and re-saved for a render. But if you run mxcl on them directly, instead of using Studio, the bug is there.

So, Maxwell experts, any ideas about what on earth is happening here?

- Casey
By pluMmet
#182109
Ahhh so frustrating...Nice work Casey!
User avatar
By tom
#182112
It seems like a plugin bug, however if you can send us the 3dsmax scene, it would be more helpful. I'm not sure if you're using the latest 3dsmax plugin (maxwell.dlr) also, please make sure the exact byte size and the modification day match the following information:
601.600 bytes
12 July 2006 Wednesday, 14:46:34
User avatar
By KRZ
#182116
interesting!
but since maxwell1.1 i can use multimats without problem sofar.
i always render directly from the 3dsmax plugin.
i hope this bug can be solved.
User avatar
By rivoli
#182128
it works fine here. I just tried with a scene which is pretty much like yours, a single MXM and then the same MXM with 3 different ids, and it works as it should. same time to reach a given sl, same benchmark, same result, same everything.
there must be something else there.
By casey
#182134
tom wrote:It seems like a plugin bug, however if you can send us the 3dsmax scene, it would be more helpful.
Sorry I didn't post a link earlier - the files are in the same location:
A: http://funkytroll.com/temp/matbug_indiv ... erials.max
B: http://funkytroll.com/temp/matbug_multi_material.max

and you will also need the mxm's:
http://funkytroll.com/temp/matbug_emitter.mxm
http://funkytroll.com/temp/matbug_surface.mxm

Let me know if you have any problems loading the scene.
tom wrote:I'm not sure if you're using the latest 3dsmax plugin (maxwell.dlr) also, please make sure the exact byte size and the modification day match the following information:
601.600 bytes
12 July 2006 Wednesday, 14:46:34
Yep, that's the one. I haven't tried it with any of the previous plug-ins though, so I can't tell if it's a new bug with this plug-in or if it's always been there.

Also note, re the other people's comments, I never have any problems with multi materials except this problem with lights. It always assigns the materials correctly as far as I can tell, and if I don't use emitters in the multi material, then the scenes come out fine.

- Casey
User avatar
By rivoli
#182139
aaa, now I got it. it seems to happen here as well, if the emitter is one of the sub-mats the scene doesn't render correctly anymore.
User avatar
By tom
#182164
rivoli wrote:aaa, now I got it. it seems to happen here as well, if the emitter is one of the sub-mats the scene doesn't render correctly anymore.
Yes, this is a known issue, emitters as sub-objects fail.
By casey
#182323
Uh, if it's a known issue, why isn't it posted in some sort of buglist?? Seriously, that really sucks. That would've saved me an entire week of time.

- Casey
By giacob
#182375
...better to sweep nonchalantly bug under the carpet..... :D
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