Mac and Metal

[marksatt]

On on the Mac, benchmarks routinely show that the gap in performance with Windows is greater at low display resolution. This means that the CPU code is limiting performance on the Mac, so it will particularly benefit from Metal, possibly more than Windows games will benefit from Vulkan/DX12.

That isn't always true. You have to check that the time spent submitting draw commands on the CPU is exceeding the time the GPU spend processing them to be sure. This tends to occur only when the number of draw commands is very high, not when the resolution is low. If reducing the resolution doesn't improve the framerate then you can usually be sure you aren't fill-rate or fragment-bound, but you could be limited by vertex processing OR CPU driver overhead, without timing information you can't know for sure which.

You're certainly right that there's more scope for CPU-side optimisations on the Mac though. Just don't expect huge FPS jumps from that alone.

 

[marksatt]

In consideration of the fact that Metal offers improvements to performance in a variety of ways, I think for now it would be exceedingly difficult to make any kind of accurate predictions about performance in any particular game whether it be a reworked existing game or a new release. </snip>

Absolutely correct.

So until we see some existing games upgraded to take advantage of Metal there's really nothing to compare yet. Also, I would guess only select leading titles will even get that attention. For the most part it will just be new titles built from the start with this tech where we see it. So we won't have any way to know really how it would have run without Metal vs with Metal.

Unreal Engine 4, as we demoed at WWDC, will support like-for-like comparisons between Metal & OpenGL since both renderers co-exist.

That's all fine. I am just saying I think it is premature to form any kind of conclusions just yet as really it is all pure speculation based on only one known point which is that it is reasonable to expect a good performance increase across the board for games using Metal. Even there, we all define "good performance" differently to some degree.

As I've said before, I am certainly looking forward to seeing what kind of games we can play and the settings we can get on them with smooth, playable performance. I just wouldn't have a clue based on what is known now if I was to pull a game out of my hat and try to speculate on what FPS increase I might see with Metal. Not only that but the tendency of many of us will probably continue to be balancing what graphics features and resolution we play at while maintaining a steady, smooth FPS. Again, lots of variables there so not an easy thing to speculate on in terms of real world performance.

Again, I think that's absolutely the right way to think about things right now. There is a lot of work to be done between now & the release of games that use Metal on the Mac that can & will affect performance. The announcement was just the *beginning*.

Game benchmarks on various Mac hardware for Metal titles will certainly be interesting, the best ones in my opinion being something like World of Warcraft which Blizzard has stated is going to be upgraded to utilize Metal in a future patch. I'd think that based on that their other games will too. Benchmarks of those games before and after on a Mac system would at least give some idea of what real FPS gain was to be had in that particular case.

Don't forget Fortnite & the new Unreal Tournament which will support both too! I'd hate all the work my colleagues & I are doing on them to be overlooked

It's worthy of note as most of you know I'm sure, what happens and is shown in one game really isn't all that telling by itself. It's trends across a good number of releases that will give a much better picture of what Metal really means to performance of OS X native games.

For now, with no disrespect intended toward anyone, I am not buying into any sort of ideas about expectations for x FPS in this game or that because the data is not existent to support those figures. You just can't extrapolate that out of stated best case percentages of multiple variables by Apple yet.

Yep, you're totally correct.

All that said, I am not a developer of Mac games so if Edwin or Blair were to come along and provide further insight into this and what to expect, I would believe them. They would know better than anybody what this means in real world terms although I wonder if they would not be hesitant to make any forecasts either until they have some code written and built using this to test for themselves. And then there is probably an NDA at this point anyway so I imagine we'll have to wait on any news like that.

I forgot to mention that regardless of what one might think of the chosen game by Epic to demo Metal at the keynote, one thing was certain. Epic pointed out that they observed major gains to performance in the game being shown when built with Metal. That game might not have looked all that impressive visually, but the demands on the system are which meant it actually was a good demonstration of Metal. I think too many people just looked at the graphics style without taking that into account even though during the demo it was mentioned how much was going on concurrently to put all those pixels up there.

Hey DirtyHarry50, as I've mentioned before I'm the Mac graphics programmer @ Epic & I used to do much the same job for Feral, so I'm no novice .

I can confirm that Billy's statement that we use 70% less CPU time to render the Fortnite demo using Metal versus OpenGL is correct. Everything else should be judged when we actually ship as you've suggested above.

Visually there's more to come from Fortnite than what was shown in the demo, some things we wanted to show were sacrificed as hitting the WWDC deadline was tough. OFC not many Macs will have a strong enough GPU for Shader Model 5 graphics features but Metal will allows us to have most of them as an option whereas we can't currently have any with Mac OpenGL.

 

[Renzatic]

I assume you are talking about the Square Enix demo?

No, it was Ashes of the Singularity. Not exactly the most graphically impressive game from an art standpoint (at least not yet), but the massive amount of ships, each shooting projectiles that render their own particle effects across a huge gulf of space was absolutely amazing.

The Square-Enix demo was impressive too. But considering it took, I believe, 4 Titans running in an overclocked, watercooled PC to run it, I wouldn't consider it a good example of what up and coming DX12 games are going to look like. It's a better showing of the extent of its capabilities.

edit: here's the video

Blah. Youtube tags don't work, it seems. Click Here For Spaceships

 

[TallManNY]

Cool. Well my iMac that I buy at the end of this year or next year will have whatever top line GPU apple offers. So I expect to get in on that shading action!

 

[marksatt]

I doubt it. I imagine there is the possibility that Metal and DX12 can perform equally, but way, way more resources will be spent on optimising the code on DX12. One can dream, though...

Ultimately all the APIs in the world have to drive the same GPU - and ideally that should be the only limitation. Getting there takes time though & Microsoft have the advantage of a mature, highly optimised graphics stack to build on. Judge Metal/Vulkan/DX12 when they are all released.

 

[marksatt]

Especially for that part, I was one of them that were left concerned. The visuals were indeed not something that could justify the context under which they were presented (e.g. a new revolutionary graphics technology that will bring a new breath to Mac gaming). At least they should give away some facts/numbers. For instance, it would be useful if they at least shared how the game was running before and after metal (fps-wise), or how many polygons they could have with and without it, or - at the very least - how implementing it with Metal affected in a positive way the minimum specs to run it.

Heck, even Elder Scrolls Online looks better and it is not implemented with Metal (hey Zenimax, that was a hint ). I think Epic should have supported their case better.

We did mention the 70% reduction in CPU time needed to render which presently is the only statistic to share. It means Metal shouldn't get bottlenecked by the CPU-side driver as often as OpenGL does & we can use that CPU time for something else.

What wasn't clearly stated was that Metal will allows us to add more rendering features* to the Mac version of UE4 than we can with our current Mac OpenGL renderer, as they weren't ready to show at WWDC. Unfortunately that's the nature of having to work to tight deadlines on new technology.

As other people have mentioned it is too early to jump to conclusions. The WWDC announcement was really for developers & is the beginning of the transition from OpenGL to Metal on OS X, not a guarantee that we're all going to make Mac games run 2x faster tomorrow

* For Macs with very fast GPUs!

 

[antonis]

We did mention the 70% reduction in CPU time needed to render which presently is the only statistic to share. It means Metal shouldn't get bottlenecked by the CPU-side driver as often as OpenGL does & we can use that CPU time for something else.

What wasn't clearly stated was that Metal will allows us to add more rendering features* to the Mac version of UE4 than we can with our current Mac OpenGL renderer, as they weren't ready to show at WWDC. Unfortunately that's the nature of having to work to tight deadlines on new technology.

As other people have mentioned it is too early to jump to conclusions. The WWDC announcement was really for developers & is the beginning of the transition from OpenGL to Metal on OS X, not a guarantee that we're all going to make Mac games run 2x faster tomorrow

* For Macs with very fast GPUs!

Thank you very much for the clarifications. I've attended Epic's presentation in WWDC with great interest. Yes, CPU-load reduction was the one that got my attention, I just hoped that there would be more facts for comparison between the current state (pre-Metal era, if I might call it that) and the upcoming (post-Metal era). I guess that's because we are all impatient (I know I am for sure) for something that will put Macs on the gaming scene as equals to the PCs, for the first time.

 

[Dirtyharry50]

Have you seen this? Its a Blizzard game, which is still in development. Do you think it will benefit from Metal? <joke off>

Have you ever played World of Warcraft in a raid at 1440p on ultra using an iMac with a mobile GPU?

Yeah, I would be very surprised if that did not benefit substantially from Metal. They are not idiots at Blizzard. They would not spend the money and go to the trouble unless there was clear benefit to performance in their eyes. As for that game, whatever it is, I'm not interested enough to look considering the backlog I already am playing through. With a little luck, a few of the games I've yet to get to will get the Metal treatment and I will wind up being glad I was slow to get around to them.

I will just add also that Blizzard has long deliberately delivered games that can run on a very broad range of hardware and made some deliberate tradeoffs in doing so I'm sure. The benefit there in reaching a larger audience is obvious and no doubt many other companies attempt similar although not always to the extent they do. A game does not have to look like The Witcher 3 on maximum settings and very high resolution to be a good looking and fun to play game, you know? I don't consider various graphics styles to be a negative. I do not care to have everything attempt to look realistic. I mean, consider another form of entertainment: comic books or animated films and cartoons. These would suck if made to look realistic much of the time. They are supposed to look the way they do. It's a part of what is cool about them. In my mind it is an important part of what looks cool in something like WoW. I do not want my Tauren Warrior to look like a real steer at the OK Corral. I want him to look like a cartoon crazy cow with ridiculous oversized armor and weapons. Making that fool dance and seeing other people do it is all part of the fun.

Great graphic presentation is not exclusive at all to realistic graphic presentation. Fantasy does not need to look real all the time because after all, it isn't real.

I know you weren't really talking about that but rather just pointing out a particular game that I am guessing is not demanding visually to make a point. It made me think about the above in terms of graphics though and want to just express my view there. Even in the case of cartoony graphics there can be tons of cool effects and stuff going on that still are demanding when they are all enabled in options.

 

[Dirtyharry50]

Don't forget Fortnite & the new Unreal Tournament which will support both too! I'd hate all the work my colleagues & I are doing on them to be overlooked

Hey DirtyHarry50, as I've mentioned before I'm the Mac graphics programmer @ Epic & I used to do much the same job for Feral, so I'm no novice .

Fear not, all the work you guys have been doing absolutely will be appreciated here. I have no doubt it will also be appreciated by very many Mac gamers who like myself are always quite happy to get high quality native OS X releases of great games to enjoy.

Thank you so much marksatt for so much expert confirmation and detail there. I recognized your name but somehow dumbbell here either forgot or had missed that you work for Epic. Come to think of it, I think I recall reading in the past about how you had worked for Feral previously, etc.

It is cool to hear we may be able to see some OpenGL vs Metal comparisons with Unreal Engine games. It'll just be interesting to see if that comes to pass just for fun.

I should tell you that personally I liked how Fortnite looked, thought it was a great demo and it made me excited about the game coming up. It is highly likely that I will purchase and play that one. As for Unreal Tournament for Mac? That's a no-brainer if ever there was one. I am very much looking forward to that. I've been an Unreal fan since the first Unreal game and the first Unreal Tournament up to the present day. I've been meaning to download the current build of UT for Mac and give it a test run. I've already heard positive feedback on that from somebody who's tried it not long ago. I'm pretty sure I already signed up or created an account or whatever for that and just haven't gotten to it yet. My less than enthusiastic comments about the demo in actuality were keeping in mind stuff I'd read from a fair number of people who didn't seem to appreciate, largely on the basis of the graphic style of the game (which again, I like personally) that it was in fact a very good demo of Metal by virtue of what was going on to display that and was even mentioned but somehow people seemed to miss that or for lack of in-depth details I guess we not entirely impressed by it. I was. Particularly near the end when there was quite a lot of stuff happening on screen all at once.

So, Fortnite looks likes damned good fun to this old gamer! Again, I am quite enthused about UT as well. My first and still fondly remembered multiplayer shooter experiences (beyond Doom on the company network after hours) are Quake and Quake II, the amazing Unreal and Unreal Tournament and Quake III Arena. As far as I am concerned when it comes to online multiplayer shooters, arena shooters are in a league of their own that is far above the likes of CoD with its bazillion unlocks, airstrikes, drones, zombies, 4 map packs per game that put the total price well over a hundred bucks and that oh, so special community. Haha! Actually, I can have some fun at that in smaller doses but I like the single player there more than the multiplayer.

How's that for nothing to do with Metal and more than you could possibly have wanted to hear about? ;-)

Anyway, I apologize for not remembering who you are and I certainly do respect your expertise as well as appreciate you taking the time to be here and share with us information that is interesting and credible. So thanks very much for that.