How powerful is iPad for 3D Ogre apps?

[d000hg]

I was surprised to see that iPad uses "PowerVR SGX 535 GPU" which as far as I can see supports SM3.0 (or maybe higher), when used in other products. Obviously iPad doesn't run DirectX but does it really support proper modern shaders?
How does it stack up on pure performance for rendering/graphics? The 535 is apparently used in Intel PC integrated graphics, so does that imply iPad has similar GPU power to a business laptop with integrated Intel graphics? The CPU is slower of course... and what's the situation with memory? Does the 256 RAM get shared with the graphics and main system, or is there additional dedicated graphics memory?

[so0os]

PowerSomething = Intel GMA 500, check the specs and benchmarks here: http://www.notebookcheck.net/Intel-Grap ... 614.0.html
But keep in mind they are lower, cause voltage is lower in iPad. Also, it is intended for smartphones, so rendering at bigger resolution may kick performance in the ass as well.

Frankly speaking, I have no idea, but don't expect too much.

[d000hg]

Useful link, thanks.

I am just trying to get a grip what spec Windows PC an iPad might be approximately comparable to.
BTW, can you render at different resolutions on iPad to reduce fill-rate problems, like 512x384?

[so0os]

As I said, I don't know about the fillrate performance there, but to do such thing, you would have to render to texture most certainly

[warmi]

Useful link, thanks.

I am just trying to get a grip what spec Windows PC an iPad might be approximately comparable to.
BTW, can you render at different resolutions on iPad to reduce fill-rate problems, like 512x384?

About 1/500 performance of a high end dekstop graphic card.
In other words, back to about 2001-2002 in terms of fillrate ( but of course, with better shaders etc )

[d000hg]

2001/2 dedicated GPU you mean?

[warmi]

2001/2 dedicated GPU you mean?

Yeah.

In other words it is slow.

If you want to deploy to multiple devices (iPads, iPhones etc) then do your testing on iPads as they are the slowest in terms of 3d rendering ( mostly because they have to deal with a lot more pixels while still utilizing the same GPU)

[JDX_John]

Is it a realistic proposition to have an Ogre app cross-running on PC & iOS right now? When I took a quick look at the Ogre iOS docs it seems things like shaders were not supported (I might be outdated). Does the materials system in Ogre have enough flexibility to handle such a wide variety of systems or do you end up with entirely separate assets in your iOS app - maybe the same names but tailor-made for that platform's limitations?

[NeARAZ]

Basically, capabilities of iPad/iPhone3Gs/4 are good - it supports shaders (roughly SM3.0-like), float/depth textures etc.

However, speed is really "not the best", to say at least. For example, a tangent space normalmapped+specular shader done in a naive way, with one quad covering whole screen would run at less than 10 FPS. I just wrote about some common (not Ogre specific) optimizations for iOS (applies to Android as well), and you can see how much time a simple fullscreen plane with that shader takes there: http://altdevblogaday.com/ios-shader-tr ... over-again (tests were done on iPhone 3Gs, and since iPad has about 5x more pixels, it will be about 5x slower).

In other words, combining something like two textures, plus occasional object with a hacked/optimized normal map with one directional light is everything you can do right now.

[so0os]

Yuo should also aim at fixed point (as opposed to floats)

[Morgoth]

Sorry for digging old post but I'd like to clarify few things on this topic. (I hope it help anyone)

In general I think you underestimate iPad hardware, keep in mind that it has Apple A4 chip which is few times faster than 3GS's chip. iPhone 4 has A4 also and even with its Retina display (4x pixels to render) it's still faster than 3GS for the same game. So fillrate is not a problem here. iPad has resolution comparable to Retina's (not exactly the same but similar) so it's not true that 'since iPad has about 5x more pixels, it will be about 5x slower' - Apple engineers are not so stupid to make device with bigger screen but the same hardware

And it's not true that iPad can't do nice, rich gfx, for example see games/demos like 'Infinity Blade' or 'Epic Citadel' - this is Unreal3 I believe and looking on this I don't really need anything more.

In the topic of RAM - I know it's 'strange' to read about 128-512MB devices that do fancy graphics, but iOS is done completely different way than PC OSes - first of all there's NO real multitasking (even if Apple says there is ) so almost nothing disturbs your application and you get much more stable FPS than on any PC.


But the most important thing IMHO I can find in this topic and many others, is the approach under common title 'porting Ogre to Android/iPhone':
Let's see this from different side - You take big, general GFX engine from 'big PC' that is already optimised in some way for nVidia/ATI, you try to port it to the **cell phone** (and porting here doesn't mean re-do optimisations for new platform but just 'make it compile') then you run some fancy demos with Phong shading or 'tangent space normalmapped+specular shader done in a naive way' and you wander why is it slow?? Guys...
This game is good for tech research but please somebody tell me - Why do you need Phong-shaded bumpmaps with specular on device with less than 4in display, when 1/3 of it is covered by fingers?

I don't mean to be rude - don't take me this way. I just want to point out some faults in thinking about 'portability' - the main strength of iPhone was not gfx capabilities but brand new ways of interaction with it.

BTW I haven't been here for few months but few days ago i saw topic about 'porting' Ogre to C64 and... I was so amazed that so many people have so much belief in this old 8-bit, 1MHz CPU

[warmi]

I am not using Ogre ... I am using my own engine complete with just about everything "serial" ( vertex transforms, software skinning, animation blending) optimized with hand-coded Neon code so your point, while valid in general, doesn't apply here.

iPad 1 has terrible fillrate issues as compared to 3gs simply because it is using the same GPU while pumping way more pixels. The CPU can help some ( for instance optimized software skinning will bring down GPU utilization big time which in turn means more fillrate) but ultimately it is what it is - there is only so much fillrate available.

Of course you can do cool graphics on iPad 1 but that wasn't my point - my point was that if you design your game to push iPhone 3gs to its limits ( in terms of fillrate) and then try to run it on iPad 1 , it will end up being dog slow and you will have either lower your resolution or simplify shaders.

iPad 2 on the other hand is a dream ...

A simple fillrate demo (http://www.warmi.net/tmp/Demo2d.mov) which is just dumping as many 32x32 alpha blended sprites on the screen as possible while still maintaining 30 fps, running on different devices produces this:


1. iPhone 1st gen – max around 350=400 sprites
2. iPhone 3gs - max around 1700-1800 sprites
3. iPad 2 - max around 12 000 sprites