OGRE3D, really slow?

OGRE3D, really slow?

Postby Julius » 01 Dec 2015, 13:22

Interesting comparison between the OpenWM old OGRE3D based renderer and the new OSG one:
https://www.gamingonlinux.com/forum/top ... ge=1#r5840

I would not have expected such a massive difference and now I am wondering if Stunt Rally has to run so badly either or if it is just OGRE3D that slows it down...
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Re: OGRE3D, really slow?

Postby charlie » 01 Dec 2015, 13:27

I'm not sure if it is correct to characterize Ogre3D as really slow. It is a game engine. It does things in a certain way. That way wasn't ideal for OpenMW. There may be performance bottlenecks as well, as it is likely not as well optimized as OSG or the OpenMW implementation on top of OSG, but it is much harder to produce a well optimized and very generic 3D game engine than it is to work with something very specific in scope, which arguably both OSG and OpenMW are. I feel like I'm being a bit vague, which is because I do not know the code/structure/topics well enough when it comes to these projects and 3D coding, but drawing the simple conclusion isn't always reaching the right conclusion. You know what they say... there's lies, damned lies, and statistics.
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Re: OGRE3D, really slow?

Postby CryHam » 01 Dec 2015, 22:32

Hello and welcome. Thank you for repoting your issue and letting us know of the problem. Please wait until somebody will..
Ah wait, this is actually a project I was developing. LoL. Kidding.

Right, OK, so from what I know (read on forums or heard from scrawl), OFC pls correct me if I'm wrong:
1. Ogre is really old, like from 2006 or bit later, designed for Direct3D9 and OpenGL2.
Such hardware has big limits (compared to new things now). Half of stuff is done on CPU (lots of unnecessary GPU calls, state changes, scene graph stuff etc.)
2. OpenMW has a lot of batches/objects drawn on scene. This is due to how Morrowind did things in the past I think.
3. OSG is somewhat newer, uses OpenGL3 (only, and not at all DirectX) and this makes it more efficient on things I put in 1.
4. SR suffers from too many batches too but believe me, I've did reduce it and it's really not that bad as in OpenMW. So, nope it does not run so badly.

I don't think the benefit for SR would be that big (or even could be small).
Main issues in SR were due to Ogre's Terrain implementation (it just sucks (too much CPU use and too many batches) for 1025, 513 is well ok).
And OFC Paged Geometry's shit done for each vertex for all vegetation model in page when switching, this produces lag (delay) when driving in dense vegetation, makes it not smooth, introduces crap page size etc, and limits us for just few tree/rock models. But that was the way it was done back then.
Lastly no Hardware Instancing for static/dynamic objects (nor for vegetation). This matters a lot in tracks like Crazy with huge number of them but not much on others.
Hmm also shadows (I'm not going to write about that) it simply is a lot faster to make them on newer hardware.
Sure we use shiny with shaders 3.0 to not look so crappy like evth from 2006, but that's it.
Let's not even mention effects, mkay? Issue worse than even shadows.
Ah and SR simulation or bullet doesn't really use at all CPU compared to rendering (like 5-10x less or so). So yeah we reached the limits of OGRE sometime ago.
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