Understanding iPad GPU power

charlieroberts

macrumors 6502a
Original poster
Feb 5, 2007
592
103
Sorry if this is stupid, but not being a gamer I'm having trouble understanding the following:

GPU power equates to running a high resolution game at high frame rates (right?)

So if the iPad can run Infinity Blade Dungeons at native resolution at usable fps, that makes it a pretty beefy gpu, even by desktop standards right? I mean people were complaining that the GPU in the 27'' iMac was not powerful enough to drive its huge display at proper fps!

And if so, why can it be so much better with so little power usage? I mean its not like the ARM vs Intel debate where ARM 'seems' faster and cooler because its outputting to the iPad, in this case both are drawing pixels, which should be the same on an iPad or iMac.

Any knowledgeable input is appreciated.
 

DreamPod

macrumors 65816
Mar 15, 2008
1,135
62
Actually, the new iPad's GPU power isn't all that great. Apple basically said it was twice as powerful as the iPad 2, but because the new high-res display has 4 times the pixels, the GPU needs to be around 4 times as powerful to maintain the same framerates. Games that don't take advantage of the high-res screen, however, will have VERY smooth framerates.
 

ThatsMeRight

macrumors 68020
Sep 12, 2009
2,262
124
Actually, the new iPad's GPU power isn't all that great. Apple basically said it was twice as powerful as the iPad 2, but because the new high-res display has 4 times the pixels, the GPU needs to be around 4 times as powerful to maintain the same framerates. Games that don't take advantage of the high-res screen, however, will have VERY smooth framerates.
There's one small difference: so far there are zero apps that make use of the iPad 2's GPU at 100%, so it doesn't matter that much.

It's better than what they did with the iPhone 4. The iPhone 4 had the exact same GPU as the iPhone 3GS (the iPhone 4 had to push four times as many pixels), and gaming on the iPhone 4 still goes smooth and well... on retina resolution!


Sorry if this is stupid, but not being a gamer I'm having trouble understanding the following:

GPU power equates to running a high resolution game at high frame rates (right?)

So if the iPad can run Infinity Blade Dungeons at native resolution at usable fps, that makes it a pretty beefy gpu, even by desktop standards right? I mean people were complaining that the GPU in the 27'' iMac was not powerful enough to drive its huge display at proper fps!

And if so, why can it be so much better with so little power usage? I mean its not like the ARM vs Intel debate where ARM 'seems' faster and cooler because its outputting to the iPad, in this case both are drawing pixels, which should be the same on an iPad or iMac.

Any knowledgeable input is appreciated.
Games on a PC (or a Mac), are much more advanced. There are so many more physics and stuff like that so it's much harder to run games with a smooth framerate on a personal computer than on a tablet. Tablet games aren't that sophisticated.
 

DreamPod

macrumors 65816
Mar 15, 2008
1,135
62
It's better than what they did with the iPhone 4. The iPhone 4 had the exact same GPU as the iPhone 3GS (the iPhone 4 had to push four times as many pixels), and gaming on the iPhone 4 still goes smooth and well... on retina resolution!
Speaking as a game programmer, the iPhone 4 is horrible. It is currently the slowest device to develop for due to the GPU not being able to handle the resolution - games run smoother on the crusty old 3GS. The 4s fixed that issue, but of course few people actually own 4s's compared to plain iPhone 4, so we can't take advantage of the 4s power.
 

mattraehl

macrumors 6502
Feb 26, 2005
384
1
Speaking as a game programmer, the iPhone 4 is horrible. It is currently the slowest device to develop for due to the GPU not being able to handle the resolution - games run smoother on the crusty old 3GS. The 4s fixed that issue, but of course few people actually own 4s's compared to plain iPhone 4, so we can't take advantage of the 4s power.
For 3D games, is it a viable option to run at 480x320 and just get pixel-doubling more or less for free? I always assumed that this sort of thing was possible and that games on the new iPad would be better-suited to take advantage of the GPU power by running at 1024x768 with more polygons vs 2048x1536.

It is an important thing to keep in mind when discussing GPU power though. The new GPU is probably identical to what's in the PS Vita but it's not going to be able to do as much if it's trying to push so many more pixels.
 

ThatsMeRight

macrumors 68020
Sep 12, 2009
2,262
124
Speaking as a game programmer, the iPhone 4 is horrible. It is currently the slowest device to develop for due to the GPU not being able to handle the resolution - games run smoother on the crusty old 3GS. The 4s fixed that issue, but of course few people actually own 4s's compared to plain iPhone 4, so we can't take advantage of the 4s power.
Of course it isn't as fast, but really all games in the App Store currently run just fine on the iPhone.

It might be harder to develop for, but the performance of iPhone 4 games is all but bad.
 

redman042

macrumors 68030
Jun 13, 2008
2,903
1,327
For 3D games, is it a viable option to run at 480x320 and just get pixel-doubling more or less for free? I always assumed that this sort of thing was possible and that games on the new iPad would be better-suited to take advantage of the GPU power by running at 1024x768 with more polygons vs 2048x1536.

It is an important thing to keep in mind when discussing GPU power though. The new GPU is probably identical to what's in the PS Vita but it's not going to be able to do as much if it's trying to push so many more pixels.
^^ This. Most Xbox 360 and PS3 games render at 500-600 vertical pixels (instead of 720) and then scale up. This includes all the popular shooters like Call of Duty. No one notices.
 

whtrbt7

macrumors 65816
Jun 8, 2011
1,013
72
GPU controls rendering of the graphics on the screen. If you have a more powerful GPU, it means that you can render more quickly on the screen. You do however have to take a look at what kind of rendering is done on-screen. Some GPUs are better at 2D rendering than 3D rendering. You also need hardware decoding of h.264 and mp4 on the chip so you can play back video. Game systems like the PS3 and XBOX360 are designed to render 3D graphics well. 2D graphics are rendered decently on both PS3 and XBOX360 but when you compare raw numbers and polygons on let's say a powerful PC graphics card, we're talking about a completely different gaming experience.

The reason why the A5X is seen as a decently powered processor/GPU is that it incorporates GPU on top of CPU which lowers latency to the chipset. Less latency = faster graphics. An example would be if I stuck a ball in 2 rooms instead of in the same room. The ball in the same room is faster to get to because I don't have to go as far. Specifically on the iPad 2012, you'll see that there is less lag when typing or playing games. In terms of 3D graphics rendering, it's almost like the PS2 in terms of graphics. It runs well but not spectacularly due to the size of the device.
 

vanc

macrumors 6502
Nov 21, 2007
327
4
The reason why the A5X is seen as a decently powered processor/GPU is that it incorporates GPU on top of CPU which lowers latency to the chipset.
All ARM SoC for smart phones and tablets have GPU and CPU in one package. A5X is just one of them.
 

charlieroberts

macrumors 6502a
Original poster
Feb 5, 2007
592
103
So...

I think I'm now further away from getting it.

Could for example a nvidia 9400 (IGP in many macs) play Infinity Blade Dungeons at the iPads native resolution?

Or even a AMD Radeon HD 6770M?
 

DreamPod

macrumors 65816
Mar 15, 2008
1,135
62
Of course it isn't as fast, but really all games in the App Store currently run just fine on the iPhone.

It might be harder to develop for, but the performance of iPhone 4 games is all but bad.
Because they are all dumbed down to function decently on the iPhone 4. In some cases (like Infinity Blade II) features are disabled on the iPhone 4 so that it can maintain the framerate. And now this is going to happen again with the iPad 3, few console-quality games are going to take full advantage of the high-res screen because it will affect framerate.
 

tsekh

macrumors member
Apr 13, 2010
87
0
And iPad/iPhone's screen is a smaller than your average gaming laptop or TV. Even though the resolution may be very high, you can "cheat" by reducing significantly amount of details compared to games developed for the desktop/consoles.
 

Mrg02d

macrumors 65816
Jan 27, 2012
1,127
1
Don't forget, apple likes to wow people and we all have 14 day return policies. They also know MANY ipad1 and iPad 2 users will upgrade and thus have a basis for comparison. Guess what I'm going to do if the iPad 3 winds up feeling like it just got a camera upgrade? I don't care for numbers as much as I care for feel. If I don't feel like my iPad 3 was worth upgrading over the iPad 2, then I'll send it back. The iPad 2 screen isn't bad at all, and crisper letters won't be enough to keep me with the iPad 3, not with a 14 day money back return policy.

Matt