[Plugin] OBJexporter v3.0 20130131

TIG · 16 Apr 2011, 16:06

Sketchup's own OBJexporter also makes individual 'distorted' images when a texture has been 'distorted' by UV mapping - simple rotations or scaling shouldn't produce multiple images.
I added the feature to mimic it because otherwise you don't get the correct 'distortion' - I have previously tried the very method you outline in your code snippet but it never gave satisfactory results. The flattenUVQ method is actually in the code 'unused' [until the more recent updates that make distorted images...].
A distorted texture has 4 uvs but a triangulated mesh makes just 3 per facet ??

Immer · 16 Apr 2011, 21:52

Yeah, I had noticed and used the flattenUVQ method provided - I figured it was something you had brought in from someone else's code but didn't use. I didn't see it in the latest version so I thought I'd include it in case you didn't have an archive of older versions.

Don't get me wrong, it's awesome that you've managed to export non-linearly distorted faces accurately, however for many situations a linear approximation is preferable, especially if lots of additional textures or a complicated group layout present problems - like if you intend to use the exported object in a game engine, or want to fine-tune the UV mapping in another program. It may even be what was actually intended: for example UVTools' spherical map apparently uses distorted textures when linear interpolation is the correct method. In fact I'm not sure it's even possible to specify a lineraly distorted face in Sketchup. I've yet to find a way to, for example, squeeze a rectangular texture onto a trapezoid so the edges and center-points line up perfectly, and that's UV mapping 101.

All I'm suggesting is a checkbox on the option screen to choose between the accurate method and the "clean" one, it should just be a matter of changing the logic to


if "face is distorted"     *AND* "use accurate method"
   create accurate texture
   export face using accurate texture
else
   output face with normalized UVs # normalizing should have no effect on non-distorted faces

Alienizer · 17 Apr 2011, 01:48

*** BUG REPORT ***

Using this model from the 3D warehouse...

Error 404 (Not Found)!!1

(sketchup.google.com)

it export just fine, except the last line in the mtl file is "newmtl fueg" and nothing else after. The file is lock for writing, and after closing Sketchup, the reminder is written to the mtl file.

TIG · 17 Apr 2011, 12:43

It is a 9Mb SKP and makes an OBJ file with 41 million lines of code so taking 5min+ to complete isn't surprising!
It worked fine for me...
The only 'error' was it didn't write '#EOF' into the end of the MTL file but that's just for me so I know it's done all materials [but it had?]

Alienizer · 17 Apr 2011, 15:42

@tig said:

It is a 9Mb SKP and makes an OBJ file with 41 million lines of code so taking 5min+ to complete isn't surprising!
It worked fine for me...
The only 'error' was it di dn't write '#EOF' into the end of the MTL file but that's just for me so I know it's done all materials [but it had?]

I let mine site all night for 9 hours and the last line of the mtl file still was "newmtl fueg", and the exporter stutus said it was done in 66 secs. So I closed Sketchup and that commited the buffer to the mtl file and it was then complete!

TIG · 17 Apr 2011, 16:16

Strange - might be a memory issue ?
Also the missing [but not fatal] '#EOF' in the MTL was puzzling as there were no error messages ???
If I get to the bottom of it I'll let you know.

Alienizer · 17 Apr 2011, 16:46

@tig said:

Strange - might be a memory issue ?
Also the missing [but not fatal] '#EOF' in the MTL was puzzling as there were no error messages ???
If I get to the bottom of it I'll let you know.

This is the second model it did this. The first one, I thought it was Sketchup because when I closed it, then file became complete. I don't remember which one it was! I know the file doesn't get closed because it has a write lock on it until you close Sketchup, even though the exporter is done without any errors!

I have a suggestion Can you incorporate the fix reverse back face material in the exporter? Perhaps add a checkbox for that opton? Maybe it's faster to do it as it goes then using both plugins? I'm not the expert so I don't know.

Thanks TIG, your exporter is by far the best the way it is.

Alienizer · 20 May 2011, 19:05

TIG, does your exporter use the object axis to orient the triangle? The reason I ask is, if I change the axis from blue up to blue down in a group, the triangle face is reversed when exported, and the ray/triangle test shows that it hit the backface when in fact it did not! Same happen with the SK obj exporter. Any idea? thanks.

xlntgraphix · 25 May 2011, 00:06

Thanks TIG! I'm new at this (less than a week) but this is exactly what I'll need for my 1st project. I still haven't really grasped the why to choose "group -vs- component" strategies. Now, in an above reply, it seems you were adding a "when to or whether to" aspect, where exporting is concerned. Have I mis-understood you? Could you please clarify? Again THANKS for this awesome plug-in. -XLNTgraphix

tichit · 29 May 2011, 13:09

Thank you so much, this plugin is very useful for me.

Alienizer · 19 Jun 2011, 00:24

One more model that the texture does not export properly but it does with the skp obj exporter...

Error 404 (Not Found)!!1

(sketchup.google.com)

Beside that, you rock, so as your exporter, thank you.

remon_v · 29 Jun 2011, 08:44

Great work on the OBJ exporter
So if I understand correctly it is not possible to export quad polygons atm?

Cheers
remon_v

TIG · 29 Jun 2011, 09:46

@remon_v said:

Great work on the OBJ exporter
So if I understand correctly it is not possible to export quad polygons atm?

Cheers
remon_v
No, all faces are 'triangulated' - which is a requirement for many renderers anyway...

remon_v · 29 Jun 2011, 09:51

Yes true, for Octane it is. Why I'm asking is because I want to intrigate SU in my Workflow for architectural modeling. So I want to model the basics in SU and export to Modo, add the organic stuff and render. I just tried accutrans to detriangulate, but it doesn't work for a 100%.

TIG · 29 Jun 2011, 10:33

Of course the built-in OBJ-exporter in Sketchup Pro lets you specify triangulation or NOT...
Why not get the time limited version and use it for just that [you can run versions in parallel] - the improvements in v8 makes it worth upgrading anyway...
My tool is intended for those 'Free' users who want some OBJ-export capability - but limiting it to triangulation and meters is the price you [don't] pay ...

redlerred7 · 28 Aug 2011, 13:32

I normally export as .X with a similar plugin. I ask: will this make 2k texture image files if you're whole 20k face model is UV Mapped almost completely with projected textures?

TIG · 28 Aug 2011, 14:00

If the textures are simply positioned or rotated/scaled one image-file is used for all versions and adjusted within the OBJ code itself, but with distorted/skewed textures passing the 4 required vertex-normals to a 3-vertexed triangle-face is awkward [impossible?] - this tool and the Pro OBJ-exporter make separate image-files for each face with such a distorted textured material. The Pro version does 'reuse' some image-files that have the exact same distortion, but my exporter does not [it makes one image-file for every distorted texture]... SO if you have a complex set of faces with skewed textures you will get a lot of image-files exported...

pcfreak1997 · 2 Oct 2011, 19:56

Love it! This is the best I've seen yet!

marietjie · 6 Nov 2011, 16:59

hello.thank goodness for clever people

Shi-Gu · 14 Nov 2011, 02:34

Works perfectly for me, thankyou so much for this plug-in!