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Why are the Combat Mission games poorly optimized?


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The bulk of the processing in CM is accurate real world ballistics math, insanely complex armor penetration models and LOS/LOF calculations covering every spot on the maps. Something few games attempt.

CM has a 'sweet spot' where gameplay flies with the right size forces fighting on the right size map. If you're a little too ambitious it can result in a LOT more calculations. As map sizes grow linearly the necessary calculations grow exponentially. I just looked up Metro Exodus on Youtube. Hmmm, it seems like a simple FPS shooter game. Pretty graphics but not much going on 'under the hood'.

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4 hours ago, MikeyD said:

The bulk of the processing in CM is accurate real world ballistics math, insanely complex armor penetration models and LOS/LOF calculations covering every spot on the maps. Something few games attempt.

 

4 hours ago, MikeyD said:

I just looked up Metro Exodus on Youtube. Hmmm, it seems like a simple FPS shooter game. Pretty graphics but not much going on 'under the hood'.

 

Try playing Graviteam games. Smooth performance, insanely complicated calculations. More realistic ballistics than CM. (but worse interface and gameplay)

Please stop propagating the myth that the CM performance problems are due to simulation calculations. Those calculations are not going on while the game is paused, but still the performance is the same, whether you pause or not.

 

5 hours ago, sovietpolarbear said:

why I can't achieve a high frame rate on any battle size despite having a modern gaming pc.

The honest answer is that CM is based on an ancient engine that does not take advantage of modern CPUs and graphics hardware. And no, that's not an attack on BattleFront. It's just how things are.

The only thing you can really do to improve performance is going for a computer with very high single-thread performance. Usually this means going for as many GHz as possible, rather than multiple cores.

Edited by Bulletpoint
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6 hours ago, MikeyD said:

The bulk of the processing in CM is accurate real world ballistics math, insanely complex armor penetration models and LOS/LOF calculations covering every spot on the maps. Something few games attempt.

In turned based mode the performance is the same. But everything is calculated in advance. In other words, there are zero calculations going on and performance is still abysmal.

No, calculations are not the reason.

Edited by Bufo
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Does Graviteam games have the same free camera that can jump all over the battlefield without affecting performance. Doing that on the fly would take a lot of calculations, even if a lot is done beforehand - or?

@Bulletpoint never have played Graviteam games, but can you elaborate on "more realistic ballistics than CM"?

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43 minutes ago, rocketman said:

Does Graviteam games have the same free camera that can jump all over the battlefield without affecting performance.

Yes, Graviteam has a free moving camera that doesn't affect performance by itself. In CM, when I move the camera rapidly and turn it, I get a quite big performance hit.

43 minutes ago, rocketman said:

@Bulletpoint never have played Graviteam games, but can you elaborate on "more realistic ballistics than CM"?

One example is tank shells and even machine gun tracer bullets hitting the ground at shallow angles and skipping off. You won't see that in CM.

The vehicle damage model is also much more advanced than in Combat Mission. Tracks come off, making tanks veer off course, they can spill fuel, and the risk of the tank catching fire is based on the exact percentage of fuel left in the tank, etc.

But this is not a sales pitch for Graviteam. Those games have plenty of their own problems too. I was just answering the question about the CM poor graphical performance.

Edited by Bulletpoint
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 I've noticed if I receive armoured re-reinforcements there is a noticeable drop in performance. In general scenarios with plenty of armour suffer severe performance hits. Not so much with larger infantry engagements.

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I have always found its buildings and trees that are the killer. 

I have an i9-10750 and a RTX 2080 Super Mobile.  I get the exact same FPS as on an i7-8750 and GTX 1050.  And that is on slightly lower than high settings for both.  I get a new laptop every year and get zero improvement in performance in CM.  A comparable game that doesn't take real advantage of modern PC architectures is Steel Beasts.  The i7-8750 is at 30 fps at middle graphics settings and the new i9-10750 gets 60 at max settings on the same scenarios.  That shows me that investing in better systems has some impact on Steel Beasts, and no impact on CM.  

The only real difference from an architecture perspective between the two games is CM is on OpenGL and SB is DirectX.  That decision to stay on OpenGL, when even in 2007 it was obvious that it was a deadend, continues to haunt the CM game.  But BFC REALLY wanted the 1-2% Mac gamer market and us PC players are suffering for it.

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53 minutes ago, Thewood1 said:

CM is on OpenGL

If I play War Thunder on opengl I get around 50 fps on average with maximum settings in QHD resolution. The video quality and demand is incomparable between the two (in War Thunder it is so much higher).

IMHO the problem is not the opengl here, but the unoptimized or just simply badly written code for the engine. Thats it, nothing else.

Edited by Bufo
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It is OpenGL.  But CM uses an old library.   BFC has stated as much.  The version of the OpenGL library they are using is very old and is barely supported by GPU makers.  If you notice, no one plays CM with Intel GPUs.  And even with AMD and nVidia, you sometimes have to do a dance with older versions of drivers.   I think the reasoning behind not upgrading CM to the more modern OpenGL libraries and Vulkan was continuing Mac support and the work needed to take update the code that dates back to CM1.  Another factor was supporting legacy hardware that some of their customers continued to use.

I'm not saying CM2 is completely optimized.  I am just putting together the various messages BFC has given over the years for poor CM performance on modern hardware.  I have a six year old lenovo laptop that runs CM2 better than anything since.  Thats just an example.

If you want another gamer with a similar, but slightly better, issue, look at X-Plane.  I have been flying XP for almost twenty years.  When i7s started coming out, players began noticing that performance seemed to  have plateaued or regressed.  Laminar Systems was using OpenGL libraries that were old and not updating to newer ones.  Again, OpenGL was used to support Macs, which the dev loved.  Laminar started a project two years ago to get off of OpenGL and on to Vulkan/Metal.  Vulkan was supposedly the "new" OpenGL.  Guess what?  Its two years on and its still not complete.  But the betas were a massive improvement in performance.  Now the issue is if Vulcan will be fully supported by Apple.  Its been kind of a mess.  But one that could have been avoided, just like CM.  When the project started, customers were screaming for them to go to DirectX.  But, again, a dev wanted that 1-2% of the PC gaming market.  And again, the players are paying the price.

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My impression is that at least some of the performance problems in CM are due to the engine constantly loading and reloading textures, sounds etc. from the harddrive, instead of just caching them on game load. I'm no computer expert, but I base this hunch on how the game often seems to drop down to minimal graphics detail (texture quality/draw distance) for a moment, stuttering a lot, then redrawing the graphics.

The problem of general lowish FPS might be some bottlenecks with the geometry rendering stressing the CPU. Which could be the reason we are seeing performance depend so much on single-core speed. I'm wondering if it's partly because of a lack of LOD scaling. Vehicles and trees have levels of detail, but I don't think the infantry have? Which would explain why big city maps such as Aachen with loads of buildings and trees are generally playable, but if I play a couple of battalions on open steppe, performance drops like a stone.

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On 7/1/2020 at 8:28 PM, Thewood1 said:

I suspect our two suppositions are related.  CM does what it does because its built on an old foundation when PCs had below 2Gb of usable RAM and limited GPUs or none at all.

Yes, I understand that the engine goes way back and was never programmed by a big software company with an army of employees. But I'd love to see a CM based on modern computer hardware some day.

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