Jump to content
Sign in to follow this  
chris330

Operation Flashpoint & Armed Assault Game Engines

Recommended Posts

Hi I was wondering if one of you clued up guys could give me a brief as to the differences between OFP and ArmA's engine. I'm curious as to why frame-rates are so much poorer in ArmA than they were in Flashpoint given that the engine looks so similar in both - on the graphics settings I have set it at.

Is it due to ArmA simply having more 3D detail and thus more faces to render or is there some major difference between the two? I haven't run OFP on this machine yet so perhaps it is caused by Vista reacting badly with games?

If it is caused by more faces then I've heard even a very souped up graphics card won't help this as it's the processor's responsibility not the card's to render 3D objects. Is this true? Is that what you call a hardware bottleneck?

Share this post


Link to post
Share on other sites
Is it due to ArmA simply having more 3D detail and thus more faces to render or is there some major difference between the two? I haven't run OFP on this machine yet so perhaps it is caused by Vista reacting badly with games?

Of course there are many many differences between OFP and ArmA, not only regarding the rendering, but also the artwork.

In OFP, models were made up from far too many 'sections' (every section needs a render state switch). This may have been OK in time of hard-wired graphics pipelines, but it is no more acceptable for the programmable GPUs, since there is a lot going on when switching shaders a.s.o.

In this case, ArmA's models are much more optimized for today's hardware. This efficiency gain is used for much more detailed units (thus neglecting the potential increase of FPS).

As for rendering, OFP used simple per-vertex-lighting, whereas ArmA has a much more complicated light-model for the sun (HDR, shadow map/volume, a.s.o.) that requires lots of GPU-power more compared to OFP's light-model.

Also, ArmA's terrain rendering is much better than OFP's highly inefficient terrain. I don't know whether OFP optimized the terrain by grouping neighbouring tiles with the same texture into one render batch: My guess is not. In the worst case OFP had to switch texture for every terrain cell you see on the screen.

The other inefficiency was: Transition textures. The transition textures took a lot of GPU-memory; ArmA uses texture splatting to render different surfaces in a cell. Thus transitions are created by texture filtering in hardware and don't take texture memory that may be used up by more detailed textures.

Quote[/b] ]If it is caused by more faces then I've heard even a very souped up graphics card won't help this as it's the processor's responsibility not the card's to render 3D objects. Is this true? Is that what you call a hardware bottleneck?

As said, ArmA's artwork is much more detailed; there was also a post by Maruk or Suma (don't remember who, but it was in one of the Vegetation performance threads) who said that ArmA has problems with overdraw -> engine is pixel-bound.

One of the solutions is indeed: Throw a GPU with more fragment processors at it (though newer GPUs are reconfigurable, so they can dedicate more processing units to fragment operations).

Others are: Reduce screen resolution, better culling (especially occlusion culling) algorithms, less demanding shaders.

For Rasterizer-based graphics, the CPU doesn't do any rendering: It just fills the GPU-memory with the geometry/texture data, sets up the render state and tells which buffers to render.

Share this post


Link to post
Share on other sites

If your system is newish, Chris330, then it should run it fine. Newest drivers etc.? I have a mid-range PC and it works well with ArmA. I can get far better framerates on ArmA at 5000m viewdistance and high settings than I can in OFP at 2000m.

I'd say although poor performance is synonymous with ArmA for some, it is your setup that is the cause of the awful performance, even if the "blame" is ultimately placed on BIS for not optimising their game for all hardware combinations.

I know some who have Vista that have played the game well, so I don't know if it's that. There are threads to troubleshoot in this forum.

P.S. I liked your SA80 for OFP, before the UKF ones came out biggrin_o.gif

Share this post


Link to post
Share on other sites
Hi I was wondering if one of you clued up guys could give me a brief as to the differences between OFP and ArmA's engine. I'm curious as to why frame-rates are so much poorer in ArmA than they were in Flashpoint given that the engine looks so similar in both - on the graphics settings I have set it at.

Is it due to ArmA simply having more 3D detail and thus more faces to render or is there some major difference between the two? I haven't run OFP on this machine yet so perhaps it is caused by Vista reacting badly with games?

If it is caused by more faces then I've heard even a very souped up graphics card won't help this as it's the processor's responsibility not the card's to render 3D objects. Is this true? Is that what you call a hardware bottleneck?

It would help if you tried ArmA yourself, than you would see what it`s about. The price of it can`t really be an argument not to buy it. wink_o.gif

Share this post


Link to post
Share on other sites
P.S. I liked your SA80 for OFP, before the UKF ones came out biggrin_o.gif

Lol I was just thinking about that only today! Yeah I thought given the new set-up and decked settings it would be fine. Sounds like I need to sort out some drivers.

@vektorboson

That's some post I understood barely a third of it to be honest. What I gleamed from it was that there are some quite key differences between OFP and ArmA. Oddly enough most sound like optimisations like the render state switch you mentioned. I assume now there's no requirement for a face to carry an associated state variable and processor power behind it to determine whether it's set at true or false. Also when you say raster based does that mean the ArmA's engine does no vector calcs on 3D objects? It just informs the graphics card where to put pixels on the screen?

Great post, curiously though everything you've said makes me think I should be getting much better performance than OFP not less which I am getting.

@Mr_Tea

I've bought myself a copy a few days ago. I got one off E-Bay bought and delivered for a fiver. The credit crunch means my days of browsing through google and buying new from the most convenient outlet are permanently over biggrin_o.gif

Share this post


Link to post
Share on other sites
I got one off E-Bay bought and delivered for a fiver.

Thats an absolute bargin! xmas_o.gif

Share this post


Link to post
Share on other sites

Thanks for the great insight VB smile_o.gif

Share this post


Link to post
Share on other sites

Please sign in to comment

You will be able to leave a comment after signing in



Sign In Now
Sign in to follow this  

×