Split Ogre in OgreCore and Ogre3d

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Re: Split Ogre in OgreCore and Ogre3d

Post by syedhs » Thu Jan 27, 2011 9:31 am

The thing is I can see that Ogre team members would not likely (I think, I am not Ogre team member :mrgreen: ) do this, so this idea can only go forward if there is someone (who presumable have great interest for this feature) step forward and does all the changes needed. I can see the changes can be quite huge - separation of Ogre into core, resource manager etc at first probably doesn't sound too difficult but the changes in the end have to be beneficial ie

1) the high percentage of Ogre users who use Ogre as it is doesn't face difficulties after the modifications.

2) the users who will benefit from Ogre separation do indeed get the benefit. The component they have (non-Ogre) can be plugged in without too much difficulties - it is fair that you shouldn't expect plug and play anyway.

3) Other necessary features like multithreading can be done easily anyway without extra burden to Ogre team and contributors. Eg if Ogre core is multi-threaded, the resource portion should be friendly (ie you can choose to multithread or remain single-threaded).

I think achieving all 3 is quite an uphill task, but I could be wrong.
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Re: Split Ogre in OgreCore and Ogre3d

Post by Zonder » Thu Jan 27, 2011 11:25 am

I would see this as a multi stage process as well.

Somthing like below

1. Rename Ogre to OgreCore
2. Create OgreTools project
3. Move all classes from OgreCore into OgreTools that don't belong in OgreCore (This should ne non breaking no namespace changes)
4. Make a list in order of features to abstract
5. Add Abstarcts / Interfaces namespace (should this be a seperate library??)
6. Create the interfaces for each feature in order that ogre needs
7. Implement 1 feature at a time into OgreTools and OgreCore at the same time from the list

This would probably create alot of individual jobs but you would need to break this down into small chunks to be able to do it
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Re: Split Ogre in OgreCore and Ogre3d

Post by Chris Jones » Thu Jan 27, 2011 12:54 pm

I'd definitely like to see this happen but sadly won't have time to contribute until my project has reached a place where i can use this.

Could OgreTools be called OgrePlatform (or similar) instead, i don't think "tools" is appropriate.
Add Abstarcts / Interfaces namespace (should this be a seperate library??)
These (where possible) shouldn't be interfaces (virtual functions), they should just be normal function calls.

I don't see why this can't occur gradually, if the project was set up, code/features can be moved across over time.
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Re: Split Ogre in OgreCore and Ogre3d

Post by CABAListic » Thu Jan 27, 2011 1:34 pm

Please keep in mind that what you are proposing here is essentially a redesign of Ogre. As such this is a colossal amount of work that would need detailed planning and careful execution. So far, all of the posts in this thread are relatively superficial, not really more than a vague idea.
Don't get me wrong, I like the idea as much as you, but to really work on it we'd need to dig deeper. And it would be work towards an Ogre 2.0.

Realistically speaking, though, I'm not convinced such a major break for Ogre 2.0 will ever happen. I find it more likely that this decoupling of responsibilities in OgreMain could happen in smaller chunks; we might begin with a separate math library as has been requested over and over again. There's also been suggestions to move the script parsing functionality to a separate plugin. I think those are smaller, contained projects which are far more realistic to be happening for Ogre 1.8 or 1.9, and we could continue from there.
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Re: Split Ogre in OgreCore and Ogre3d

Post by Zonder » Thu Jan 27, 2011 2:29 pm

Yes it is somthing that has to happend gradually. Just making the decision to have the 2 dlls is the important bit the other dll could be empty but as long as it's there and part of the build. As cabalistic says individual units can then be split out. I don't think I was making my self clear above I was not thinking all at once it was a process that would go over many versions of ogre.
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Re: Split Ogre in OgreCore and Ogre3d

Post by CABAListic » Thu Jan 27, 2011 2:35 pm

The split would not be OgreCore / OgreTools. It would be more like OgreCore / OgreMath / OgreResources / OgreWhatever. Just splitting in half doesn't really make sense if your goal is to reduce individual responsibilities of the libraries ;)
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Re: Split Ogre in OgreCore and Ogre3d

Post by sparkprime » Thu Jan 27, 2011 2:49 pm

How much stuff would need to be included in order to satisfy the dependencies of the RenderSystems?

I'm thinking things like Pass, Textures, GPUProgram, etc.

I think that collection of stuff would be a good base level API. It would be useful for people who want to implement their own engine at the level of D3D/GL but want the platform abstraction OGRE provides.

On top of that can be scene managers, entities, nodes, cameras, etc. Also another component could be scripting as mentioned.

As for Vector3 and friends, perhaps that can be a level even below the render systems, but I don't care personally either way as I am not interested in using Vector3 outside of ogre.

As for plugins, I don't see any reason to add more plugins. In fact I don't see any reason to keep the existing plugins. All we need is the ability to include and link in a subset of the codebase, which most libraries provide without needing plugins. E.g. Bullet has a math layer, various utilities, optional shapes (gimpact, softbody) a collision layer for just finding out about colliding pairs, and a dynamics layer if you also want to simulate motion. You can link in as much or as little as you want. Very similar to OGRE but much simpler.
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Re: Split Ogre in OgreCore and Ogre3d

Post by Klaim » Thu Jan 27, 2011 6:51 pm

The split would not be OgreCore / OgreTools. It would be more like OgreCore / OgreMath / OgreResources / OgreWhatever.
That would be an excellent idea : that would greatly encourage Ogre code modification as it would limit the link time to each module modified instead of whole OgreMain project.
Added to the repo cloning, I think it would make (at least me) a bit more easy to gather energy to try to fix or add something in the Ogre code.

The progressive view of it would be like Qt module splitting : really helping.

That said, those modules would still be required by OgreCore, or could we identify some that could be isolated enough to allow a "lightweight" Ogre setup?
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Re: Split Ogre in OgreCore and Ogre3d

Post by CABAListic » Thu Jan 27, 2011 7:36 pm

Well, the idea would be that OgreCore is self-contained (except for math, perhaps); instead, some (most?) of the other libraries would likely depend on OgreCore.
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Re: Split Ogre in OgreCore and Ogre3d

Post by _tommo_ » Thu Jan 27, 2011 7:56 pm

Another idea:
to me an API-level retrocompatibilty in an effort like splitting Ogre would be nearly impossible to obtain.
It would be very much like a fork, at least in the near period where it would be really unstable and unreliable.

On the long run retrocompatibilty could be implemented mapping each "Ogre Classic" feature on some other component library, so that a project that just links all of them can use everything the current Ogre has.
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Re: Split Ogre in OgreCore and Ogre3d

Post by sparkprime » Thu Jan 27, 2011 9:42 pm

_tommo_ wrote:Another idea:
to me an API-level retrocompatibilty in an effort like splitting Ogre would be nearly impossible to obtain.
It would be very much like a fork, at least in the near period where it would be really unstable and unreliable.
Not necessarily, it can be just a build system thing.

Ultimately, we have a set of classes. All we are doing is choosing what directories the source code for those classes lives in, and which libraries those classes are compiled into.

It may be that in the course of restructuring, we discover that there are strange dependencies, e.g. maybe RenderSystem depends on Camera whereas really it just needs a matrix (I have no idea if it currently does or doesn't). In that case we may change some APIs slightly but that should be rare and hopefully not happen at all.
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Re: Split Ogre in OgreCore and Ogre3d

Post by Zonder » Thu Jan 27, 2011 10:22 pm

CABAListic wrote:The split would not be OgreCore / OgreTools. It would be more like OgreCore / OgreMath / OgreResources / OgreWhatever. Just splitting in half doesn't really make sense if your goal is to reduce individual responsibilities of the libraries ;)
Yes quite true.

I do like the idea of the core render been seperate. Gives people a base for there own rendering engine without the bloat of the full ogre library may actually make the community grow even more (not that it needs it really :))

Thinking about it the renderer is probably the easier part to split as it's right at the top/bottom depending on how you see abstraction :)
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Re: Split Ogre in OgreCore and Ogre3d

Post by jacmoe » Fri Jan 28, 2011 2:02 am

:)

That's actually oxymoronic : replacing the rendering engine of Ogre with your own ... :wink:
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Re: Split Ogre in OgreCore and Ogre3d

Post by Zonder » Fri Jan 28, 2011 9:54 am

Yeah it is a bit contraditory :wink:
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Re: Split Ogre in OgreCore and Ogre3d

Post by sparkprime » Fri Jan 28, 2011 1:04 pm

Not really. If you give it a better name that 'rendering engine' it becomes perfectly reasonable:

Rendersystem portability layer
|
Render pipeline
|
Scene graph
|
Scripting

It is perfectly reasonable for someone to implement their own render pipeline that is highly threaded, or a scene graph that is not based on SceneManager, just as it is for them to replace the render system with some new thing.

The reality may be that these things are too tangled to make this possible, but the theory is sound.
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Re: Split Ogre in OgreCore and Ogre3d

Post by Zonder » Fri Jan 28, 2011 1:14 pm

we wen't saying it isn't valid. we just mean you come here for a rendering engine but then implement your own on top of the 3D API abstraction layer :)
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Re: Split Ogre in OgreCore and Ogre3d

Post by jacmoe » Fri Jan 28, 2011 3:41 pm

Pipeline is a good word for it. :wink:

If you people could cook up possible library names and what goes into them and how they're connected, it would probably help it move towards possible realisation. :)
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Re: Split Ogre in OgreCore and Ogre3d

Post by CABAListic » Fri Jan 28, 2011 3:52 pm

Keep in mind, though, that the probability of realisation increases considerably if suggested splits do not require *major* rewrites/redesign. Ogre has been designed as a higher-level 3D engine, so the likelyhood of it becoming a lower-level abstraction layer with additional tools on top of it is not very large, imho. (It's also not what I would personally want Ogre to be.)
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Re: Split Ogre in OgreCore and Ogre3d

Post by Zonder » Fri Jan 28, 2011 8:05 pm

I think this is more coming about because of the phone market and needing libraries that can be optimised to the apps needs. Phones won't get huge amounts of of ram and any ram going should be for textures!! :). Ogre is a beast in size but that is fine for the desktop/laptop/arcade machine market not the lower hardware and been a high level rendering engine you currently can't chop out the bit you don't need. This also effects consoles as well thinking about it
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Re: Split Ogre in OgreCore and Ogre3d

Post by jacmoe » Fri Jan 28, 2011 11:25 pm

Right.

Look in http://code.google.com/p/gamekit/ I am sure I saw a TinyOgre folder in there somewhere.. :)

<edit>
It's OgreLite:
http://code.google.com/p/gamekit/source ... 2FOgreLite
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Re: Split Ogre in OgreCore and Ogre3d

Post by Zonder » Sat Jan 29, 2011 1:53 am

jacmoe wrote:Right.

Look in http://code.google.com/p/gamekit/ I am sure I saw a TinyOgre folder in there somewhere.. :)

<edit>
It's OgreLite:
http://code.google.com/p/gamekit/source ... 2FOgreLite
good catch :)

see people want it and are doing it lol
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Re: Split Ogre in OgreCore and Ogre3d

Post by voyvf » Sat Feb 05, 2011 9:13 pm

I've already got way too much on my plate to contribute, but I would love to see this happen. :D
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Re: Split Ogre in OgreCore and Ogre3d

Post by nec » Tue Mar 01, 2011 7:48 pm

OgreCore should only be the default implementation of a virtual system interface set. So you can use as it is or you can override a part of it.

Exemple :

virtual system define interfaces for
- Memory Access
- File Access
- Timers
- ... Other system relative concepts.

There could be one OgreCore for each supported platform which would implement the whole set of system abstraction interfaces. If i want to use my own memory manager, i can implement the memory management interfaces and give it to OgreCore which override the default implementation.
You all know how hard it is to gather all middlewares under the same memory manager. it might be easier if all middlewares made the abstraction of the system.

Ideally Ogre should only focus on 3d graphics services so it should not come with OIS and stuff like that and should be abstracted from the system. But as Ogre offert many samples to make the learning easier it becomes more like a GameEngine with many missing parts (sound, network, ...).
So to avoid Ogre to become a full game engine it should abstract some parts a little bit more to made it more pluggable.

In few words : i should be able to remove all system parts from ogre easily to put mine. So moving them to OgreCore could allow demo sample to use OgreCore default implementation and allow me to use my own implementation if i want to.
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Re: Split Ogre in OgreCore and Ogre3d

Post by CABAListic » Tue Mar 01, 2011 10:57 pm

Uhm, OIS is not a part of Ogre; it's only used in the samples, Ogre isn't tied to it in any way whatsoever. Just to avoid confusion...
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Re: Split Ogre in OgreCore and Ogre3d

Post by che1404 » Thu Mar 03, 2011 8:53 am

Hi there!
I found C4 Engine architecture a great example to follow...
Have a look!
http://www.terathon.com/c4engine/architecture.php

Regards,
Roberto.
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