Hey guys, I did a lot of number crunching. Theoretically, having 1.28x as many pixels as the iPhone 4, it the iPad should only run ~80% as fast in terms of FPS. And, in fact, that is how it works out. I've analyzed not only the overall tests but the low-level 3d tests such as shader usage and fill rate from http://www.glbenchmark.com/. Though the iPhone's CPU is indisputably down-clocked, the iPhone 4 and iPad both use the exact same GPU core with the same memory bandwidth and clock. This is why Infinity Blade can have shiny armor on the iPhone 4 but not on the iPad; 20% difference can be huge when we're talking about the difference of a "shininess shader." However, the iPad can keep up with the iPhone 4 in terms of triangle throughput, etc. Which is why iPad HD games are smaller, for ex. Shadow Guardian is only ~3/4 the size on the iPad. Hypothetically, SG uses extra textures for effects, such as specular highlights (shiny things) or bump mapping. These are areas that would slow down a scene by about less than or equal to about 20%. They don't need to be included on the iPad version because they can't be used and maintain the same framerate. This is why you see shiny metal in Infinity Blade on the iPhone 4 and not on the iPad. But do not lose heart, iPad owners! The hardware isn't anywhere near pushed to its limits. Unreal Engine 3 and Rage were adopted from console technology; the fundamental technologies are different when you come from a regular video card model to a deferred tile-based renderer like the ones used in iPads/Pods. If you look at the quality of Infinity Blade or Rage, and consider that they actually have a good amount of room for optimization, firstly the iPad won't be left behind much longer, and secondly the games we see actually are not the pinnacle of what is possible on the current hardware. And iTouch 3g and iphone 3gs users rejoice; you get between 2/3 and 3 times better performance than the iPhone 4 with the same scenes, though your processor is slower! Of course, there's a little bit more to the 20% extra performance the iPhone 4 has. It has a tiny little screen. In my opinion, though things "really shine" on the iPhone 4 Retina sometimes, mostly, having the huge screen and playing field makes up for some lost details. But that's just my opinion.
Does this mean a second gen iPad with retina display (presumably) would need a processor 4x more powerful than the current ones?
I started suspecting the 3rd gen touch might have to do a lot less work rendering games when I started reading lots of people complaining about lag in fifa when I had none granted the cpu is slower you also don't have gyro or a camera but I think the lack of retina comes with some advantages. At the very least it pulls it's weight well with the new models thanks to the same GPU and less pixels.
Assuming a next-gen iPad would have a Retina display which doubles its current horizontal and vertical resolutions, and that it would run games in that native resolution... It would need 4X the current pixel fill-rate, and 4X the current pixel shader performance to run games at the same level of performance as the current device on its screen. And this wouldn't be enough to bring shininess into Infinity Blade The above graphics upgrades would also require significant increases in available memory bandwidth, and putting all those together would equal much greater battery usage. Such a device would have a screen resolution of 2048*1536, well over 50% more pixels than in FullHD (1920*1080). Considering even Xbox360 and PS3 struggle with performance in FullHD games, and that mobile graphics hardware is far from similar capabilities, it's fair to assume that the next iPad will: 1) be powered by magic, or 2) not have a Retina Display, or 3) have guidelines that encourage developers to run high-performance games in less-than-full screen resolution
interestingly enough, we're only pulling in 64-bit memory bandwidth, probably around 200MHz clock, and a mid-range SGX, the 535, with a theoretical fill cap of 1 GPixel/sec. Apple is rumored to be licensing next-gen PowerVR technology, SGXMP. It's like putting the high-end SGX together, with multiple cores; fillrates in excess of 4x what the iPad has are possible. Now the iPad has ridiculous battery life if you don't have 3G; the screen consumes around 85% of the power. This can be seen when you play a video with VLC (which eats up CPU power) vs. the hardware decoder; you get ~8 hours with VLC and ~10 with the hardware decoding. Advancements in batteries are being made all the time. So let's say we use a 4-core SGX variant that uses 4x the power, or 40% of what's available. And Apple waits a bit and puts a 50% better battery in. (That's realistic in the next product cycle after this one). We've got our chipset and our power covered. So this is all speculation, but technically speaking, the next iPad, if it were possible to make a "retina" resolution LCD, could theoretically drive it at roughly the same speed as the current one, with the same speed memory and a 256-bit memory interface (graphics cards have up to 512-bit). The resulting increase in necessary RAM without any cooling would be the killer, really. Or, alternatively, they could somehow up-clock the SGX to 400MHz and double the RAM interface width and use 2x as fast RAM. But the amazing thing when you get right down to it is the fact we're playing such gorgeous games at such a high resolution. 1024x768 is the regular aspect ratio version of the HD that the consoles (PS3, XBox360) put out! If you see something that even *compares* to them, at this resolution, you're already seeing a miracle. PowerVR does *magic* with what they have, and tile-based deferred rendering should be used more in the high-performance space. Apple has done a bang-up job. My $.02 though, if apple comes out with any revolutionary display technology, it will be that you can turn off the screen and there's magically an e-ink display you can read from. Which seems technically possible, with how e-ink works. My bet is it'll be called iInk.
