I wanna write my own OpenGL type graphics library. But I don't know how to access hardware acceleration on the iPhone.
Hardware acceleration is exposed most directly by OpenGL — it's a very low-level library. Apple doesn't allow any lower level access and the hardware underneath isn't documented in any event.
Most third-party libraries are much higher level than OpenGL, talking in terms of scenes, objects, lights, etc, and all sit on top of it.
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I want to do some DSP effect processing, create effect like flanger, echo, etc.
Could it be done via OpenAL? Or should I use enterely different framework/library?
Since iOS 5.0 some of the DSP effects are natively supported by OpenAL.
For example, reverb is supported with emulation for more than 10 different spaces (Small/Medium/Large Room, Medium/Large Hall, Plate, Medium/Large Chamber, Cathedral and several variations).
You can find a good reference implementation in the ObjectAL wrapper. The repository is available at https://github.com/kstenerud/ObjectAL-for-iPhone
Grab the source from this repository, load "ObjectAL.xcodeproj" and run the ObjectALDemo target on any iOS 5.0 device (should also work on the simulator). This will give you a good starting point and feeling of what the reverb effect is capable of. I personally recommend taking advantage of the ObjectAL library instead of working with OpenAL directly.
Good luck with your project!
Just write your own audio library. iOS devices don't have hardware acceleration for OpenAL. It isnt particularly difficult to do, and then you can also use apples audio units (some of which are hardware accelerated).
I have a couple ideas for some 3D games/apps and need to know which 3D engine to go with. I like the high-level approach of Unity and UDK. I have done some 2D games using cocos2d before, but I'm entirely new to the 3D world, which is why i think Unity or UDK are a good choice. I know about the differences in licensing, and i am more concerned with the learning curve instead of the licensing cost.
Plans:
A 3D "side scroller" that goes forwards (up) instead of to the side. Third person space ship. This would primarily be for learning. Tilt to steer, tap to jump. Very simple graphics, vertex coloring would be enough.
A 2.5D "side scroller" like the above one but with a car. This game would generate the levels randomly out of a couple prefab blocks of a certain length that fit together seamlessly.
A 3D augmented reality display for pilots with a terrain mesh loaded from DEM data. Accelerometer and GPS access required.
Other important points:
Must be able to tie in to In-App purchases.
The more community content like tutorials and forums the better.
Ability to add third party libraries like Flurry Analytics is a big plus! But i guess this isn't possible?
Which engine would you recommend for these projects, and why? Preferably, i'd like to pick one and stick with it.
You’re going to have a way, way better time developing with Unity. UDK’s got a fantastic, incredibly capable engine, but its tools don’t have the ease-of-use of Unity’s, its developer documentation leaves a lot to be desired, and the community hasn’t been using it for long enough for there to be much help to be found there. Some quick Googling suggests you can write your own Objective-C plug-ins for Unity games, so in-app purchases and third-party libraries are definitely a possibility. I think Unity’s your best bet.
What about cryengine? it free for non commercial use and also provides mono c#.
Check it out CryEngine
I'm using a series of shaders to perform realtime image processing on the iPhone (3GS/4/iPad). The fps isn't what I'd like it to be.
Are there any tools that I can use to help me work out what the bottlenecks are?
I assume you already know that performance tests on the Simulator are worthless and that you're testing on real metal, so Instruments is always a good place to start - specifically in your case you'd be interested in the OpenGL ES and OpenGL ES Analyzer instruments.
Generally speaking for GLSL, there's a list of common GLSL mistakes at the OpenGL.org site. The O'Reilly labs "iPhone 3D Programming" book has some further hints, such as avoiding expensive operations in conditionals, and watching for texture lookups.
Also, it's going to depend on what kind of image processing you're doing; if you're trying to apply heavy Photoshop-esqe filters that would give a quad-core pause to render, it's going to be costly on a lowly phone.
The only currently available tool is the PVRUniSCo editor, which will give you a cycle count for each line of code in your shader (though only on Windows, it seems).
Is there any GPGPU library for iPhone?
The original iPhone and iPhone 3G support only support OpenGL ES 1.1 fixed-function pipeline and do not provide a programmable pipeline (no shaders) and therefore cannot be used as general purpose computation devices, at least at the OpenGL abstraction layer.
iPhone 3GS and iPod touch 3G support OpenGL ES 2.0 programmable pipeline. However, it looks like there are limitations like lack of antialiased shaders.
Regardless of the support for programmable shaders in 3GS, I don't think the GPU is powerful enough to be used as a general purpose computational engine.
The iPhone GPU isn't built for general purpose computation, so hacking it for such features would be very limited and slow at best.
Pre 3GS' even have fixed pipeline chips, which makes computation on them impossible for almost all practical purposes.
I'm writing a game for iPhone/iPod.
My engine is using OpenGL-ES, and this means game requires some performance.
(realtime games, not a static board-game like games.)
I looked at basic sound framework in iPhone, there're several frameworks,(Core Audio, Audio Toolbox, OpenAL...) but I cannot determine differences of them in detail.
I think OpenAL will gain best performance, but it's just a guess with no clue. And iPhone/iPod is a music player hardware, I cannot know in-depth features of iPhone/iPod.
I'm new to all of those framework, so I have to study one of them. And now I'm choosing one.
The features required for me is:
Delay-less playback. Sound effect should be a realtime feedback.
Streamed long music playback with very small memory footprint.
Volume control per playback of sound effect.
Mixing. Multiple difference sound effect can be played at same time. (around 4 or more)
Other feature required for games.
Hardware acceleration (if exists)
Realtime filtering effect (reverb, echo, 3D, ...) if possible.
...
Can you recommend a framework for my game? And some explanation about each framework also will be very appreciated.
You can do everything you want with OpenAL. It's what I'd recommend for a game.
Plus, it's the only framework for 3D positional audio which often goes hand-in-hand with a 3D game.
OpenAL, Core Audio, AudioToolbox etc. are wrappers around the same things: namely, Apple’s own audio processing features. OpenAL is just a different interface but has the same performance as Core Audio, as it sends commands to the same things.
There are several other “audio engines” out there that are just wrappers.
At risk of tooting my own horn, Superpowered is the only audio SDK that outperforms Apple’s Core Audio on mobile devices. It’s specifically designed to outperform every single one of those, with lower memory footprint, CPU load and battery usage. For example, the Superpowered reverb is 5x faster than Apple’s. See http://superpowered.com/reverb/