posted 08-14- 07:45 PM               

Not so hypothetical situation #1: I'm in OPS b1.3.0, I select a part, right click and select Add Child/Model. Nothing happens. None of the Add Child options seem to do anything. Why is that?

Not so hypothetical situation #2: I'm happily replacing model parts of a plane one by one (all the parts are separate groups within a single obj file but importing more than one at a time causes problems). The parts are all coming in fine except some parts seem to be rotated 90 degrees from the rest of them. Why is that?

Not so hypothetical situation #3: I have not yet textured the obj models that I'm importing (I'm still in the learning phase ;-) but all the parts come in absolutely black. Is that normal? (No pun intended. I'm assuming it is since there are no UV coordinates or normals in the model yet.)

Not so hypothetical situation #4: I've got some LODs to texture sent to me from a third party (can you say ZEPPELIN parts from RONIN?). I import the LODs into OPS where they have a few reversed normals but the geometry looks about right. I export them to obj format but this invariably misplaces some of the vertices and does a poor job recreating the obj faces. Is there a better way to do this?

That's all for now!

posted 08-19- 07:12 AM               

quote:

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Not so hypothetical situation #1: I'm in OPS b1.3.0, I select a part, right click and select Add Child/Model. Nothing happens. None of the Add Child options seem to do anything. Why is that?

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It just some menu items I added when I put the context menu for the part tree in. Should probably have grayed them out or something. You can achieve the same thing by just copying and pasting another part.

quote:

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Not so hypothetical situation #2: I'm happily replacing model parts of a plane one by one (all the parts are separate groups within a single obj file but importing more than one at a time causes problems). The parts are all coming in fine except some parts seem to be rotated 90 degrees from the rest of them. Why is that?

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quote:

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Not so hypothetical situation #3: I have not yet textured the obj models that I'm importing (I'm still in the learning phase ;-) but all the parts come in absolutely black. Is that normal? (No pun intended. I'm assuming it is since there are no UV coordinates or normals in the model yet.)

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Probably. It may also be that OPS imports a material file that has no textures and colours and defaults to black (0,0,0) Nothing is really defined until you assign some textures and colours to the parts.

quote:

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Not so hypothetical situation #4: I've got some LODs to texture sent to me from a third party (can you say ZEPPELIN parts from RONIN?). I import the LODs into OPS where they have a few reversed normals but the geometry looks about right. I export them to obj format but this invariably misplaces some of the vertices and does a poor job recreating the obj faces. Is there a better way to do this?

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Bryan

[This message has been edited by Bryan Russell (edited 08-19-2000).]

posted 08-20- 08:31 AM               

So to follow up:

N.S.H.S. #1 OK. Got it.

In N.S.H.S. #2 you are correct in that I created the parts in their correct orientation. I did the model all as one .obj file so I could get the allignments correct. So all I really need to do is reposition them in OPS? Seems odd but I can live with odd.

In N.S.H.S. #3 OPD does not seem to be reading the .mtl file at all. I've tried this with several .obj models now with normals and texture coordimates. In what directory do I need to put the .mtl file? Also, on SV's site I saw a reference to a "Texture Index" and a "Index to Material Table". Where would I find these?

In the past I've avoided working in MAX (mostly because I'm trying to convince people that it is not necessary for flight sim modeling) but since 99% of all other modeling people use it I may have to bow to the inevitable. None-the-less, I may write a LOD=>OBJ script. Since .obj files can vary considerably this may be pretty application specific. I can send you .obj specs if you'd like.

Thanks again.

posted 08-20- 02:12 PM               

After much debate and study I have decided to revert to modeling in ac3d for OpenPlane instead of 3dsmax. In my very personal opinion, 3dsmax is not a very good low-poly modeling tool. Also the great plugins (and getting better) by Hippie make ac3d -> OpenPlane much much faster and more efficiant too. I'm sure many disagree, that is fine - and I am not saying I am correct, only that this is my best solution at the current time.

I do not like the "do it because everyone does it" mentality, but I am learning 3dsmax for just that very reason! (and the fact that it is hard to get ac3d working with modern video cards).

Right now here is why ac3d is better than 3dsmax for OpenPlane work for me:

1. It costs about 2% the price of 3dsmax.

2. It is a mesh editor and no more, just what you need for OpenPlane. No fighting through a high-poly and animation based GUI and modeling metaphore.

3. AC3D allows for real polygons, not just triangles and quads, this is more effeciant for OpenPlane and speeds up modeling work as well.

4. AC3D can texture map just as well as 3dsmax, and texture mapping is so much of the work.

5. Hippie's plugins make working with LOD meshes a very exact one to one relationship.

6. Hippie's new plugins facilitate part positioning in a very nice way, I am coming up to speed on this, I will add more info on my site as I go.

7. AC3D has a lack of tempting poly-increasing tools

8. Andy is bettering AC3D, Hippie is bettering the plugins

9. You can easily set up and use the background image feature for your scale drawings.

10. Much quicker learning curve and maybe, at the risk of sounding proud, there is better documentation for using AC3D for OpenPlane.

Why not to use AC3D and instead use 3dsmax?

1. AC3D works on few video cards, especially bad with more modern cards. Hippie suggests that it should work well in software mode - I am investigating

2. AC3D is buggy, very buggy. I find it more than workable though, well until my background image feature stopped working.

3. 3Dsmax experience might get you a job 3d modeling some day

4. Better modeling tools, boolean, lofting, etc. Though I find you spend more time lowering poly count or fixing stuff after you use these.

5. Bryan Russell (OPS author) uses 3dsmax.

6. Impress your friends.

I am not a 3d expert by any means, and my knowledge of 3dsmax is very very small. Howerver, I have made three planes (SE5a, Albatros Dva, Fokker DVIII) are rebuilt another (Morane-Salnier N), and AC3D solution is really quite elegant. I built my Fokker DVIII in three days (12 hours), take a look at it and see what you think. It has all the low detail LODS (texture mapped too) as well as much attention paid to texture mapping. Most important of all, it did not feel like tedious work to build it, it felt like modeling! The demands I made on AC3D where met with a quick and percise response, objects where desinged - broken in half for texturing, textured, then re-joined for export.

If anyone wants to race me, I will model a plane in ac3d and someone else use 3dssmax. The judging will be on time to complete and quality of model and lack of 3d bugs. Hey, this could be fun!

I do want to re-iterate that I am not a real 3d modeling artist, but then again, so much better the defense for AC3D! Look at what a bone-head did with it! I am pleased with the results both in terms of quality and effeciency of work.

If by chance you end up using AC3D Kugelfang, let me know if you need any help or such, you will have a buddy

Now I am back to trying to get my AC3D working on my new video card

------------------
-Sv =FC=

WWI in SDOE!

posted 08-20- 09:04 PM               

quote:

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In N.S.H.S. #2 you are correct in that I created the parts in their correct orientation. I did the model all as one .obj file so I could get the allignments correct. So all I really need to do is reposition them in OPS? Seems odd but I can live with odd.

---

quote:

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In N.S.H.S. #3 OPD does not seem to be reading the .mtl file at all. I've tried this with several .obj models now with normals and texture coordimates. In what directory do I need to put the .mtl file? Also, on SV's site I saw a reference to a "Texture Index" and a "Index to Material Table". Where would I find these?

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The MTL file just needs to be in the same dir as the OBJ file and have the same base name. i.e. Hurricane.obj and Hurricane.mtl.

the SM file assignes textures based on reference, so the texture index is just the number of the texture in the SM file's texture list. SM Material tables have nothing to do with visual stuff, they are used by the physics engine to define contact relationships between things. For example a object made of rubber reacts differently than one made of concrete. Nothing to worry about here until you get to the stage of wanting to change the way your airplane reacts with the enviroment.

quote:

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In the past I've avoided working in MAX (mostly because I'm trying to convince people that it is not necessary for flight sim modeling) but since 99% of all other modeling people use it I may have to bow to the inevitable. None-the-less, I may write a LOD=>OBJ script. Since .obj files can vary considerably this may be pretty application specific. I can send you .obj specs if you'd like.

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You are right, MAX is not nessacery for Flight Sim modelling, but it is a good mesh modeler once you work it out, and you can bring yourself to ignore all of the other stuff. There was a LOD exporter posted by someone a while ago so check that out before you write something.

If you can send me the OBJ specs that would be great, although I am concentrating on VRML more as none of the MAX OBJ exporters do everthing right, and the flaws in the MAX VRML exporter are easy to live with. Try VRML and see if its any better. VRML is more self contained so there is no need for external positioning and material files.

posted 08-21- 07:36 AM               

Hmmm, the .mtl file was in the right place with the right name but I had not added the texture to the texture list. Presumably this must be done separately rather than directly from the .mtl file. Thanks for the explaination of the material table. Your're right--not a modeling concern but nice to know for future reference.

I'll e-mail the .obj specs to you.

I'll look for the LOD exporter but I was really thinking about a stand alone conversion script in Perl or Euphoria. I'm trying to teach myself visual C++ so maybe if I'm really ambitious.... I really think one of the scripting languages would be better for this, though.

posted 08-21- 08:21 AM               

The LODS do not contain the positioning matrix, well at least the LOD file Hippie creates. This remains in the sm file. I find it best to position objects in OPS, it really goes fast. I alligned the crazy Morane 3-triangle wings LODS in OPS in about 5 minutes, and added the DOF in a couple of minutes!

LODS should always be positioned centered around the origin and not rotated. Well, the vertical stab and rudder will be 90 degrees off lol, no one knows why Now you position in OPS. Now if you create or edit and lod, it will be at least close in OPS, just move/rotate it using the positining keys, this moves things in small amounts if you hold cntrl.

As far as textureing, if you are using obj then I don't know what to do. If you can get the lod into Hippie's LOD file format then texture ID is an element. You can map the texture in your program and then simply modeify the LOD file to point to the correct texture... guess this is getting wacky. For ac3d users you just set the "shininess value" to your texture ID for whatever polys you want. If you need to add a new texture, you just add a new texture entry to the asc file. I think OPS even supports adding new textures now... I have not figured out how to texture in 3dsmax and get it into OPS yet, but thanks to Bryan's post here I am getting closer )

posted 08-21- 03:26 PM               

It took me a while but I finally realized the matrix was contained in different file. Though, I'm wondering--and this may be a stupid question--are the LOD and matrix files part of the OpenPlane spec or is it something Hippie (or someone else) created to enable easier manipulation outside of the sm file?

I guess positioning the parts in OPS is all right. Everything comes in correctly except the rudder and vertical fin. That just caught me by suprise--I'm glad to see that I'm not the only one who suffers from that. As a matter of fact it will make my texturing process a little easier since I can export parts as separate .obj files, texture them and then pull them into OPS and position 'em. That way I don't have to texture the entire model in one fell swoop!

So far I can import the geometry of my .obj files into OPS but I can't seem to get it to recognize the texture. I have managed to add the texture to the texture list but I don't think the imported LOD is assigned a texture index. (I double clicked on the texture name to bring up a box where I could change the file name. I made sure the new texture was in the same directory as the old texture. I could not see it in the list though until I saved the .sm file, closed OPS and then started it up and re-opened the .sm file.) Is there any place in OPS where a part's texture index is listed?

So far the only way for me to create an LOD of a new part is to import an .obj into OPS and then export it as an LOD. It seems, however, that the LOD contains ALL the LODs of the model, not just the part I selected. At least I think this is what's happening. All I know for sure is that there are a great many more vertices and polygons than there should be for the single part. No doubt I'm screwing something up but I'll keep working on it.

If I can export a single part to LOD then I can edit the LOD and add the texture index. I keep coming up with more and more motivation to write a conversion script! I looked at some old scripts that seemed to do this but haven't had much success with them either (yet!).

Onward! Onward! The taube WILL fly! (Not to mention the L-9!)

posted 08-21- 04:02 PM               

OPS does not show you a LODS texture index because LODs do not have such a thing. Each polygon within a LOD can have its own texture index! This is very important, you may have LODS with multiple textures maped to them. Maybe a canopy gets its glass texture from one file and its frame texture from another. I have done this.

Try exporting as a LOD, edit the LOD file to hand code in your new texture index, now re-import the LOD. You should see your texture

I have always edited one LOD at a time and positioned in OPS, I find this to be a fine solution. I am experimenting with Hippie's new tools that do positioning in ac3d as well, looks cool!

If you could script out something that lets you export from your 3d program into Hippie's LOD format then you would be in great shape! The LOD file contains the mesh verts and polys, the texture index for the ploys, the texture mapping coords, and some flags and stuff.

posted 08-21- 08:07 PM               

SV,

Your page on understanding the LOD is really what got me to thinking about a conversion program. OBJ files are similar and contain most of the same information. With some careful parsing of the data an OBJ file could become an LOD file with very little to be added.

I just finished reading the OpenPlane spec doc and looking at Hippie's extractor. Now I realize that what Hippie (and maybe Bryan?) have done is write a program that slices and dices the binary .sm file to make it ASCII files, hence the LOD files. Bryan's gone a step further and added a GUI and some other abilities to make it much easier to create the object property lists. Very nice.

posted 08-21- 09:28 PM               

So, when you create a rudder or VStab in your modelling program so that it is orientated correctly (i.e. vertically), what happens is that the current matrix in the file you are importing to rotates it 90deg and therefore it appears flat.

You could just rotate it in OPS to be back to the vertical, but then you would end up with a rudder and VStab (actually only the VStab, since the rudder simply inherits the rotation from the VStab) that has upward lift from the airfoil attached to it rather than a Horizontal force as should be the case.

When you select a part that has an airfoil in OPS you will see a blue arrow appear. This is a representation of where and in what direction the aerodynamic forces are applied to the part, in this case it needs to to be horizontal. It probably doesn't matter which side the force is applied since the VStab airfoil is probably symetrical.

I hope that clears up that 'Mystery' If you need clarification please ley me know.

Now a little about Matrices in the Sm file. Matrices (and also rotation and translation )are another record type in the SM file. When the file is loaded the matrix, rotation and translation records are read and concatinated based on the hierarchy of the parts in the file. In a OPS generated file the record format is fixed per part and always follows the same pattern, so you can assume that a matrix and translation directly preceeding a part will directly effect that part. You can probably not make the same assumption about other files.