Guidelines on parsing new object format.

[todirbg]

Hi Lubos,
I want to add support for X-Plane obj8 format to Armor Paint and I want to ask you for some guidelines to conform to your code. I have some code working, just to confirm reading the file and extracting the relevant data for the moment. I see from your wavefront obj importer that you are parsing the file as a binary byte by byte. X-Plane objs are guaranteed to be ASCII text and are much easier to parse as strings. For now I am using BytesInput to get the data and read it with .readLine. It is working(on win), but I want to ask if this is OK or I should rewrite the code to read it as your parser does?

[luboslenco]

Hi! If you parse it like ObjParser.hx does it should be faster, otherwise there is not difference - both approaches work. It can also be implemented as a plugin, like import_stl does.

[todirbg]

10x Lubos,
I'll will just try to make it work for now and optimize performance later.
My first attempt was at writing a plugin, but there are considerations that made me decide to write a new parser in the main code. First trouble is that x-plane and wavefront obj share the same extension so it was necessary to look for obj8 header before calling the appropriate parser. X-plane objs can be quite complex. They include multiple objects, sometimes nested on multiple levels and those objects have transformations that have to be applied. And I wanted to have the option to append new object, because many x-plane objects can share the same texture.
I got most of this working. Just the transformations give me headache for the moment :) I have no prior experience with Haxe and I am currently looking in the libraries for functions that will allow for easier transformations :) I hope to show you something working soon.

[todirbg]

Hi @luboslenco
I was finally able to make the time to wrap my head around the obj8 transformations and the importer is ready for testing. Cold you take a look at some things and tell me if it is OK?
The main importer class is in a file Obj8Parser.hx in armorbase sources https://github.com/todirbg/armorbase/tree/obj8_import/Sources/arm/format/
I still have to optimize it, but it is producing good results.
The files changed in armorpaint sources are /Sources/arm/Project.hx and /Sources/arm/io/ImportMesh.hx and importObj8.hx
https://github.com/todirbg/armorpaint/tree/obj8_import/Sources/arm
In Project.hx I added a UI option for adding mesh without replacing the existing one. This is something that is currently not working as expected, but I am not sure the issue is with my code. When mesh is added to the scene the UV map is not updated with the UV from the new mesh. It used to work fine on the older AP ver I was using when I added this part, but it is not working anymore. The UV is there, but is not visible in 2D and the paint tools in the 3D view port do not work on the new part. Is there a way to force UV map reload when adding new mesh?
In Project.hx I changed the function importMeshBox to differentiate between Wavefront obj and obj8. Because they share the same .obj file extension the only way I could think of to differentiate is to open the file and read the first 3 lines. Valid obj8 files are guaranteed to have a 3 line header. This is something I wold like you to take a look at. It is slow because the way I did it the whole file is loaded to read those 3 lines and there is a perceptible delay between clicking on "Open" and the UI box appearing if the files are big. Is there a better way to do this? There is a new var isObj8 that is passed to function Run In importMesh.hx where the appropriate importer is called.
If you want to test it here you can find some test subjects:
https://github.com/todirbg/PZL-M-18/tree/master/objects
https://github.com/mSparks43/747-400/tree/master/objects
https://github.com/mixMugz/An-24/tree/master/X-Plane%2011/Aircraft/Antonov/An-24/objects

Best regards!