Splitting out objects in AC3D

27 Jan 2013 16:22 #6693 by Vodoun da Vinci
I have been cutting up the single object MQ-9 Reaper 3D model and creating individual objects for the various bits....left and right missiles are now separate objects as are the prop, wheels, laser turret (2 parts - ball and housing), flaps, ailerons, rudder, gear bits, etc. I have run into an issue that I'm not sure is resolvable.

Have a look:

Look at about :54 and also at 2:06. If you look closely you'll see 2 bits that attach themselves to every object I create. These are parts of the landing gear and I cannot make them go away. I cannot select them individually and delete them.

Obviously I can't animate with these bits attached to every object in the same spot. Any ideas how to get rid of them?


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27 Jan 2013 16:39 #6695 by Algernon
I've had similar issues before now, seems to just be one of those things. The only thing I can suggest is to try opening in a different package and see if you get any more control over it.

How infuriating, when everything else is going so well...

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27 Jan 2013 18:52 #6701 by Vodoun da Vinci
My Blender won't open/does not recognise these .ac files - they open fine in AC3D and work fine in FlightGear but my Blender install says they are not supported.

So, either my Blender install is compromised or there is something odd about these .ac files. :S

If I send you one can you open it and see whas' 'sup? Or put one of the new object.ac files in the development area and see if one of ya'll can see something this 3D modeling newbie is missing?


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27 Jan 2013 19:51 - 27 Jan 2013 19:54 #6704 by Neilson
I Think there is a .ac importer for blender.


I need to learn how to do this myself too

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27 Jan 2013 20:19 - 27 Jan 2013 20:23 #6706 by Vodoun da Vinci
Thanks for the link....you mean Blender doesn't work with .ac files as a native format? :ohmy:

I got to about page 5 of that discussion and realized I'm not as interested in doing this as I previously thought.... :blush: I was sure I had opened .ac files in the past in Blender.

I can't even follow the discussion and make any sense of it - my chances of modifying my new Blender install to incorporate this is about zero. I did just get a trial version of Metasequoia which does not like .ac either *but* if I'm gonna convert files back and forth between formats I'm thinking I'll do it in Metasequoia before I'll be able to figure it out in Blender.

Hopefully I can begin making some headway on this project again soon (today) as I'm rapidly becoming very discouraged. Truthfully, I have a massive aversion to even going to the main forum right now. I kind of have a real aversion/hate thing going for the whole Open Source/FlightGear thing right now so maybe I need to give it a rest for a while. I'm reading it but it isn't jiving with me in the least.


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27 Jan 2013 21:55 #6709 by Vodoun da Vinci
OK...some headway. :)

I can open my present .ac files of the objects I have cut out with AC3D and then export them as Lightwave files which are .lwo extension.

Metasequoia likes the Lightwave.lwo files just fine and it then allows me to select those little extra bits that I don't want and delete them slicker than freezing rain on my sidewalk! :woohoo: :cheer:

I then export them from Metasequoia as a Wavefront file - .obj and AC3D likes the Wavefront.obj just fine. I then export from AC3D as a .ac file and *PrEsTo!* I now have a .ac file of the object I split off without the naughty bits. :)

Unfortunately all of these files screw with the X, Y, and Z axis so I'll have to get creative with flipping the files around so they don't end up backwards and inside out when they arrive back in AC3D to be reassembled into a Reaper.ac 3D model with all the various bits ready for animation. I gotta quit for today as I am now seeing double and competely exhausted from the research and manipulations/file conversions.

I'll try and make more progress this week when I figure out how the flip the files and get them oriented correctly.


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28 Jan 2013 00:46 - 28 Jan 2013 00:48 #6717 by Vodoun da Vinci
Alrighty then. :)

Using the above outlined conversion process, I am able to take the individual objects sawn off of the original 3D model and convert them to .lwo files and import them into Metasequoia. In Meta I can remove the offending naughty bits. I then export them from Meta as .obj which is read by AC3D so I import the .obj into Ac3D and save as a .ac file.

I take the Reaper.ac and carve the parts off, import the new .ac that is a particular object (Flaps, Ailerons, Wheels, Rudder, Turret Housing, Turret Ball, Individual gear parts, etc) and assemble the whole mess in to a new Reaper.ac file that has all the objects separated. It's working..it's a pain but I figured out the axis issue and at present have a Reaper.ac with left and right missiles, left and right flaps, prop and Wheels as separate bits *without* the little floating naughty bits at the gear locations.

The problem is that we have lost the texture mapping. I can't fix it but I'm trying. So, we'll have to learn texture mapping at the same time we are learning to manipulate and separate out the objects.

Shall I proceed, Algy? Or does someone have a way of importing the files into a program that can eliminate the naughty bit without losing the texture mapping?

Honestly, I don't think Blender will help me now as I have been trying that as well and it is 100X less intuitive than Metaseqouia or AC3D. I can probably get Blender to import .ac but the interface is simply not acceptable to me...my brain cannot make Blender functional.

I hate it even more now... :blush:


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28 Jan 2013 11:33 #6723 by Algernon
OK, well I might be able to help you here, though my knowledge is almost entirely Blender based on this. First of all, a quick precis on using .ac formats in Blender.

No, Blender no longer supports .ac files natively. There are two scripts available that I know of, and they aren't difficult to install in Blender. However, I get script errors with both on them, on different tasks, which makes importing and exporting a bit of trial and error, remembering which is which - this is not recommended for a stress free experience. Stuart doesn't get these errors, suggesting it's only an issue with the latest version. Either way, it's a pain in the 'arris.

I can offer a bit of insight into texture mapping, too, for which I know the process in Blender and assume the terminology is universal, if the technique isn't. I've only just really properly figured this out, apologies if you already know it. Basically, a 3D model can be clad in one or more materials, and each material consists of one or more textures. Now, once a material is congfigured, you should be able to assign that material to any object with one simple click of the mouse. This is the case in Blender, though knowing which tiny button does what is useful for this. So here's a sample procedure:

1. I take a model which is all one object, and separate the vertices of the wings into a separate object.

2. Lets assume I've imported and exported a few times, and the textures are no longer working.

3. I select the fuselage and remove any materials attached to it. Then I create another texture, and call it "Reaper". Then I add a texture, and call it PaintKit. I set this texture to be an imported image, tell it to use my paintkit as its image, and in Blender, I set it to use a UV map, which should still be remembered by the model.

4. From here onwards, all I need do is assign that material to every object, and it should splash the paint onto the model in the right place.

The moral of this story: there is a quick way of getting textures back onto your model after import/export nonsense. The bad news - I only know how to do it in Blender. If the worst comes to the worst, VooDoo, do all the separating and then pass it on to me, and I'll try reassociating the texture.

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28 Jan 2013 11:41 #6724 by StuartC
I can glue on lost textures by editing the .ac file in Notepad++ and inserting the relevent text.

Im clever me !

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28 Jan 2013 12:26 #6727 by Vodoun da Vinci
Super Duoer thanks to both of you guys. As it was textured mapped pretty well, I'm gonna have a lookie see at the final .ac object code in Notepad. In theory, the code at the head of the file tells delineates texture mapping *so* if I compare the first/initial .ac with the final one and cut and paste the correct code I should get the mapping back.

Did I mention I now hate Blender to the point I may purge it from my computer for life? :lol:

I'll report back if I get any sucess. The cool thing is that I have a working copy of Metasequoia and it's pretty dang cool. :)


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28 Jan 2013 12:32 #6728 by StuartC
Actually, the texture file is specified in every object part.
A conventional model may have the same texture file specified in severl areas and another file specified in several more etc etc...

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28 Jan 2013 13:05 #6729 by Algernon
I'm by no means an expert on this, but I believe the UV mapping is the important thing, and the vertex data contained therein seems to stay with objects, so whichever way you do it, assigning a texture to an object ought to result in the position of that texture upon the faces of the object staying correct. In Blender, a lot of the fiddling you have to do is about seeing it rendered correctly in the 3D view of Blender, rather than affecting the model itself.

The long and short is, if you've just separated stuff and not messed around with texture settings, the UV information should be intact and assigning a texture to it in any way - be it using the 3D software or editing the text file - should still result in good placement.

Stuart, if your Notepad++ approach has resulted in little hassle, I might have to ask you to re-sort out the new Typhoon model, as it's not looking as good as the one you derived for me originally. Maybe a task swap will be in order (even though I'm failing with the F-35B)...

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28 Jan 2013 13:29 #6730 by StuartC
You want the original textures bolted back on to your last release?

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28 Jan 2013 13:57 #6732 by Algernon
Actually, no, now you put it like that... it won't work, as I'm merging the multiple textures into one or two larger ones, so the UV mapping will be all awry... my apologies :)

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28 Jan 2013 14:05 #6733 by Vodoun da Vinci
Stuart, my limited experience thus far is that, so far this one is pretty simple code wise. The original model.ac was all one big texture. As I split out individual parts the files (like LeftAileron.ac) carries with it the texture mapping from the main model.

The idividual objects are quite simple all being stripped off of a simple model.ac. :)

The resulting test models.ac, with a dozen individual obects added back in is *very* complex code wise. So, I'm trying to split off the individual objects (simple) remove the naughty bits, and then fix the mapping/code on that individual object file hoping that when I assemble them all in a single model.ac the texture will be restored.

Ya'll know what I'll be doing with every minute of spare time this week and into the weekend. ;) :lol:


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02 Feb 2013 16:56 #6839 by pjedvaj
AC3D can't import or export OBJ files as individual objects. Try to import the original Reaper model in AC3D as .DAE or .DXF file.

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02 Feb 2013 18:53 #6840 by Vodoun da Vinci
Thanks for the input, Petar! :)

My AC3D imports .obj just fine - All of the stuff I have done so far in AC3D is from an original 3D model imported as .onj and saved as .ac

The only problem is the inability to get rid of the little "naughty bits" which are left over on every separate .ac I cut off the original in AC3D. I *can* select the naughty bits in Metasequoia and get rid of them but this mean converting my .ac to .lwo and exporting (in Metasequoia after the naughty bits have been removed) as a .obj which is then imported *back* into AC3D and exported/saved as a .ac again.

Unfortunately this is breaking the texture mapping and I have been unable to resolve that thus far. :(

I do not have the option of importing the original Reaper as a .dae or .dxf. I have the options of: .3ds, .lwo, .lxo, .max, .mb, .mtl, and .obj


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03 Feb 2013 14:27 #6843 by pjedvaj
So you do have a problem. ;)

You get only one mesh that you need to cut manually and you loose the UV mapping. In Maya I used Mesh - Separate command to resolve that issue, AC3D doesn't have that option. Possible solution is to import all .OBJ objects one by one (the hard way) or to import the file in some other supported format (Collada .DAE). I don't like .3DS because it triangulates everything. You can use some 3D converter or mediator software, like Bleneder.

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03 Feb 2013 15:58 #6846 by Vodoun da Vinci
I must have a mental block with Blender as I simply cannot make it do *anything* for me.... :blush:

It took me about an hour to figure out AC3D to the point I could import a .obj, flight it/orient it correctly, resize it, move it around in the grid and then separate out off of the individual objects (flaps, ailerons, wheels, turret...everything) and save as individual .ac files.

It took me perhaps an hour with Metasequoia to achieve various degrees of sucess in importing/exporting and manipulating the 3D models.

Blender remains a completely useless tool for me after hours (cummulatively days) of reading and playing with it....it has the most unintuitive and frustrating interface I have ever seen and, unfortunately, if I have to use Blender I'll probably give up on 3D modeling as I simply do not have the available time to try and deal with Blender.

I can't make Blender do anything usefull. :( :pinch:


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03 Feb 2013 16:14 - 03 Feb 2013 16:16 #6847 by Vodoun da Vinci
Success!! :woohoo:

I found a way to remove the offending "naughty bits" in the individual objects.ac files using AC3D - No more converting and importing/exporting and no more broken texture mapping!! :cheer:

So, back to fixing all the parts and assembling them into one Reaper.ac file which will be a 3D model with separate .ac files for each part to be animated!

Super duper thanks to Stuart for tweaking my thought process yesterday after the Saturday MP Event. Sometimes a few minutes of thoughtful conversation with another set of eyes and different brain can make a world of difference.

One more reminder that *all* of this Flightgear stuff is a group and team effort and that many hands, minds, skills, and perspectives make the whole thing better, faster, and more fun. ;)


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