I've just installed the current Xcode 4 release and realized the new "GLKit" API thats also used in the OpenGL Template for iOS. So, I want to develop an cross-plattform game for iOS, Mac & Windows. GLKit seems like a step backwards in terms of portability, but the GLKit Features (specially like asynchronous texture loading) are great benefits...
How can I develop a cross-plattform game with GLKit? I would need to write any grapics code twice, right? Or is there something like an GLKit implementation for windows?
Any idea, workaround, code-design advice (how to divide the GLKit Code from other components?) is welcome - thanks!
I can't think of anything that GLKit does which cannot be replaced by non-GLKit code. It can make some OpenGL ES 2.0 tasks simpler by abstracting them away from you, but it doesn't do anything unique. The closest it comes to having something you can't replicate elsewhere (from what I've tinkered with) is the accelerated matrix and vector math functions it provides, but even those could be replaced with a little Accelerate or NEON code.
While I'd like to use GLKit within my applications, I'm still supporting iOS 4.2 with them, which doesn't have GLKit available. There's nothing that I'm currently prevented from doing because I can't use GLKit, I just have to write a little more code to handle things like view updates, texture uploads, matrix math, etc. There's plenty of documentation and examples out there for these operations, so you don't need to worry about being on your own when it comes to implementing them.
You're going to have much larger problems than GLKit when trying to make your code be cross-platform with the Mac, and expecially so with Windows. Desktop OpenGL and OpenGL ES have some differences in their implementations, and you'll need to be aware of the places to substitute one function or built-in variable for another. CAOpenGLLayer and NSOpenGLView on the Mac are also different from the CAEAGLLayer on iOS, and AppKit overall is a different animal than UIKit.
Windows will be even more of a challenge to support, because you won't be able to use any of the Cocoa frameworks, and most likely no Objective-C as well. This will take a lot more of your time than any OpenGL / OpenGL ES differences.
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I'm looking for a 2D rendering library as an alternative to CoreGraphics on iPhone. Everything in my app is pretty dynamic, which makes splitting things up into layers and animations rather hard.
I'm quite familiar with OpenGL, and that is how rendering is implemented right now. Everything would be so much easier to expand and development would go so much faster if I didn't have to worry about the low-level stuff in OpenGL, though (And my code would look so much neater :D).
I prefer C++ over Objective-C, so if you know any C++ libraries for rendering, that would be great. I can work with C too. Path-based rendering, like in CoreGraphics or the JavaScript Canvas API, would be beneficial. Would Cairo work on iPhone?
I've actually been working on my own 2D renderer, which I'll probably release even if I don't end up using in my app, because I enjoy working on it. Does the iPhone support the stencil buffer? I can do polygon triangulation, or use GLU's tesselation library, but the stencil buffer would safe a load of work in the long run.
Edit: Also, I've implemented rendering in this app with CoreGraphics before, and it didn't get as good of a frame rate as I'd like. I did some research, and people have suggested not using CoreGraphics for things that are constantly redrawing the screen. Some said CoreGraphics doesn't use the GPU, others said it was some caching mechanism. I've avoided it ever since.
MonkVG is an OpenVG 1.1 like vector graphics API implementation currently using an OpenGL ES backend that should be compatible with any HW that supports OpenGL ES 2.0 which includes most iOS and Android devices.
This is an open source BSD licensed project that is in active development. At the time of this writing it is in a very early pre-release state (very minimal features implemented). Contributors and sponsors welcome.
It can be found at GitHub http://github.com/micahpearlman/MonkVG
Also, there is a SVG and SWF (flash) renderers built on top of MonkVG:
MonkSVG
MonkSWF
Are there any engines that allow me to develop for pc and iphone at the same time? My preferred language would be c#, but that probably won't happen, so I probably will learn c++ or java.
I want a 2d engine, by the way.
No experience with it but...
http://www.torquepowered.com/products/torque-2D/
C# and Java aren't allowed on the iPhone, so a C or C++ engine would be your best bet. I'm guessing you're doing a game--if so, you'll probably want to use OpenGL. I don't know any specifically, but here's a full list.
Working with pure Core Animation layers can yield cross-platform 2-D drawing and animation between iPhone, iPad, and Mac. As an example of this, the Core Plot framework runs on Mac and iPhone from the same codebase. Core Animation lets you do some pretty complex animations and layout in 2-D.
It is against the rules in OS 4 to write an iPhone app in something other than Apple's dev tools. However, IANAL but I'd expect that it is in theory ok to take the app you made there and then try to run it on an emulation layer etc.. on the /other/ platform(s). Not sure about direct solutions, but check out the GNU Objective-C runtime / GNUStep, they might be a helpful starting point.
How hard would it be to port a flash game to the iPhone. Obviously Flash CS5 is no longer an options, I still would like to know if there's anything that can be reused? or do I have to write everything from scratch (Is Obj-C that different than ActionScript?) Is there any other shortcuts?
Also, if anyone has done this before please share your experience.
Flash is a very different platform, not only is the language change going to be an issue you're going to be going from Flash's renderer to presumably your own using OpenGL:ES.
Although another method may be to port your app to JavaScript. Both ActionScript and JavaScript are EMCAScript dialects, so very similar in that area, the APIs will be completely different though.
http://paulirish.com/work/gordon/demos/ interesting and slightly related, this is a implementation of Flash in JavaScript.
Note the new Apple T.O.S may affect you, but as far as I'm aware it's still a beta and I'm not Apple or a lawyer so I won't try and decipher it for you.
I am doing the same thing. I am using Cocos2d for iPhone. This is a pretty good 2d game engine. Actually, two apps created with it are in the current top 25. You are going to have to get down and dirty in Objective-C though. Objective-C is different from ActionScript but if you are use to object oriented programming you should be able to make the switch. Programming a Flash game is different than typical game programming done in Objective-C/C/C++. So, if you are familiar with how to do things in the Objective-C/C/C++ game programming world (render loop, capturing inputs, etc), you'll really be ok. If not, you'll have to get use to not having the Flash timeline, dealing with frames, etc. Good luck! You can do it!
read the statements from apple, no its not possible.
For my game Hudriks I used flash to build levels and some animations. For this an animation engine has been developed that supports motion tween, and then wrote JSFL scripts that goes through Flash objects and export to a format that can be parsed in my game.
For writing the JSFL - look for document called Extending Flash.
The rest was developed from scratch using Objective C with OpenGL. Do not see option of 'one-click' compilation or converting from Flash to iPhone (not considering CS5), but with developing extensions for Flash you could reuse some work.
It is hard, but it is possible. I am working on a automatic code converter now.
In discussion with some colleagues we were wondering whether OpenGL work developed for Android or iPhone are effectively interchangeable given that both support the spec.
Or is the reality of sharing OpenGL between the two platforms more a case of quirks, tweaks and not as easy as one might have hoped.
An OpenGL implementation normally consists of two parts:
1. Platform specific part. This has function usually related to creating and displaying surfaces.
2. The OpenGL API. This part is the same on all platforms for the specific implementation of OpenGL, in the case of Android, OpenGLES 1.0.
What this means is that the bulk of your OpenGL code should be easy to port.
In C, you might have glLoadIdentity();
In Java on Android, something like gl.glLoadIdentity();
So for the bulk of your code you can cut and paste, and then search and replace prefixes like 'gl.'
Now for the fun part: you really need to be careful what version you are coding against. OpenGL for the desktop has APIs which don't exist in OpenGLES. There are also some OpenGL data types specific to each platform. In addition, you have 1.0 (e.g. Android) 1.1 (e.g. iPhone) 2.0 (e.g. iPhone GS) to deal with. The differences in API often have to do with additional hardware capability, so it's not like you can write some easy wrapper code to emulate 2.0 features in 1.0/1.1.
OpenGL ES on Android is done according to Khronos Java GLES spec JSR239 , and wraps GL calls in something like glinst.glBindBuffer(FloatBuffer.wrap(data) ... )
OpenGL ES on iPhone is done using stock GL.h files and the same call will just look like glBindBuffer(data...)
The code will not be interchangeable and will cause many quirks, even before you get into the whole mess of differences between 1.0 1.1 and 2.0 APis.
Both platforms use OpenGL ES, but Wikipedia claims that Android uses 1.0 while the iPhone uses 1.1 (original and 3g) an 2.0 for the 3gs link. It's likely that at least some programs will use api functions not included in 1.0, so there won't be full compatibility between the 2 (well 3).
I have been developing iPhone Applications for a couple of months. I would like to know your views about the Quartz vs OpenGL ES 1.x or 2.0 learning curve. You can tell your perspective. My Questions are
*I am a wannabe game developer, So is it a good idea to first develop in quartz , then move
on to OpenGL ES or does it not make an difference
*Can you please tell your experiences when you were having the similar question
Thanks :)
Quartz 2D is not applicable for game development IMHO. It is a software rendering API. It won't give you realtime rendering speed. It's good for drawing charts or vector text with shadows, or for blending several images together. Just not for games. Unless you want to make a game where few images are moving against a monochrome background and even in that case I doubt it will be really smooth on older devices. I've seen some games obviously coded with Quartz. A pitiful sight.
Sooner or later you'll end up using Open GL ES or a game framework build on top of it. I recommend you to check cocos2D, SIO2 engine, or examples from SDK.
With careful programming it is possible to make an Open GL ES game with parallax scrolling and relatively small amount of objects work at 60 FPS even on 2nd gen devices. Tiny Wings is an example of such game. And maintaining stable 30 FPS is not a problem at all.
I skipped Quartz and went right to OpenGL ES. I started with a 2D sprite based game. Thought it was pretty easy.
The key is having a good example to look at. I used the Lunar Lander clone (Crash Lander), but I don't think that's easy to find anymore. Maybe someone who has done it recently knows of a better, newer example that uses current best practices.
I'm in the same boat as you describe, although I have no programming background. (Although I don't know what your background is either) Currently, I am in the process of learning to code as I learn the various API's that are available. I'm an objective-c guy going backwards to the c-based Quartz API, and it's a little bit of a challenge. Luckily, Programming in Objective-C 2.0 by S. Kochan has a great chapter on underlying C features to keep you afloat.
I have taken a couple of stabs # OpenGLES, and I have to say, that from a conceptual standpoint, I'm not ready for it. The Quartz2d API is a bit easier to learn conceptually because it's very easy to get up & running with a few commands. Right now, I'm at the point where I can define shapes and point to point images with out too much trouble.
OpenGLES is going to be something in my future, but it takes such an enormous amount of code to configure the drawing view, set up buffers, etc. If you are familiar with everything the code is doing, then it's a bit easier. However, from a learning perspective, Quartz is an easier way to get going, quickly.
Resources I'm using: The aforementioned book, and an anemic amount of blogs containing tutorials, which are limited # best. At this point, make an appointment with the apple docs and get cozy, because it's about the best (free) stuff that's out there (& exhaustive) With that said, I'd love for someone to prove me wrong on this site by posting a great resource for learning, but that's about it. Good Luck.
I have been looking for the fundamental differences so I can decide between OpenGL (ES) or Quartz or a hybrid. The good news is that the hybrid is an option. Clearly Quartz is easier to master for O-O programming and the answer from Apple appears to be that OpenGL, "...is ideal for immersive types of applications..."
http://developer.apple.com/library/ios/#DOCUMENTATION/General/Conceptual/Devpedia-CocoaApp/DrawingModel.html
I don't want to limit the category to games as I believe any game UX can be applied to a business App, a productivity App, entertainment viewing, etc. By the same token, I fully expect the technology (both h/w and s/w) to advance to make either a choice.