I'm Flash/AS3 developer and I'm wondering how some iPhone developers use vector assets in their games.
For example, "Lil' Pirates": this games looks like vector-based, it's zooming and unzooming easily, but I can't get any information about using vector assets at iOS.
Quartz 2D is a pretty lightweight framework for vector based graphics. It's very well documented...
Quartz Documentation
In particular I'd pay particular notice to layering and performance...
Quartz Layering and Performance
If performance is a worry I'd also have a read through the core animation documentation. Core animation uses CALayers to cache vectors drawn with Quartz to in-memory bitmaps. These CALayers can then be transformed and translated through the animation APIs. If you intend to perform a lot of drawing this is the route I would recommend.
Related
I would like to know what kind of advantages I get from using Core Graphics instead of Open GL ES. My main question is based on this:
Creating simple View animations.
Creating some visual appealing objects (Graphics like Core Plot for instance, Animated Objects, etc).
Time consuming (both learning and implementing)
Simple 2D Games
Complex 2D Games
3D Games
Code maintenance ad also cleaner code.
Easier integration with other UI elements.
Thanks.
First, I want to clear up a little terminology here. When people talk about Core Graphics, they generally are referring to Quartz 2D drawing, which is a 2-D vector-based drawing API. It is used to draw out vector elements either to the screen or to offscreen contexts like PDFs. Core Animation is responsible for animation, layout, and some limited 3-D effects involving rectangular layers and UI elements. OpenGL ES is a lower-level API for talking with the graphics hardware on iOS devices for both 2-D and 3-D drawing.
You're asking a lot in your question, and the judgment on what's best in each scenario is subjective and completely up to the developer and their particular needs. I can, however, provide a few general tips.
In general, a recommendation you'll see in Apple's documentation and in presentations by engineers is that you're best off using the highest level of abstraction that solves your particular problem.
If you need to just draw a 2-D user interface, the first thing you should try is to implement this using Apple's provided UIKit elements. If they don't have the capability you need, make custom UIViews. If you are designing Mac-iOS cross-platform code (like in the Core Plot framework), you might drop down to using custom Core Animation CALayers. Each step down in this process requires you to write more code to handle things that the level above did for you.
You can do a surprising amount of stuff with Core Animation, with pretty good performance. This isn't just limited to 2-D animations, but can extend into some simple 3-D work as well.
OpenGL ES is underneath the drawing of everything you see on the screen for an iOS device, although this is not exposed to you. As such, it provides the least abstraction for onscreen rendering, and requires you to write the most code to get something done. However, it can be necessary in situations where you want to extract the most performance from 2-D display (say, in an action game) or to render true 3-D objects and environments.
Again, I tend to recommend that people start at the highest level of abstraction when writing an application, and only drop down when they find that they cannot do something or the performance is not within the specification they are trying to hit. Fewer lines of code makes applications easier to write, debug, and maintain.
That said, there are some nice frameworks that have developed around abstracting away OpenGL ES, such as cocos2D and Unity 3D, which might make working with OpenGL ES easier in many situations. For each case, you'll need to evaluate what makes sense for the particular needs of your application.
Basically, use OpenGL if you are making a game. Otherwise, use CoreGraphics. CoreGraphics lets you do simple things embedded in your normal UI code.
Creating simple View animations.
-> CG
Creating some visual appealing objects (Graphics like Core Plot for instance, Animated Objects, etc).
-> CG
Time consuming (both learning and implementing)
-> OpenGL and CG are both kind of tough at first.
Simple 2D Games
-> OpenGL
Complex 2D Games
-> OpenGL
3D Games
-> OpenGL
Code maintenance ad also cleaner code.
-> Irrelevant
I'm looking for is a heuristic for determining which of the primary graphics methods for iPhone/iPad development would be the most appropriate solution for a given problem.
Simple answer:
Quartz 2D
Use Quartz 2D for custom interface elements to give a stylized look to your application.
Core Animation
Easier to use, although used where performance is not critical. Great for quick animation routines. a lot easier to do effect in. Used with UIViews as well. Can be used to create simple fine games. like pong or card games.
OpenGL ES
Great for performance critical games. A bit more complex but once you can get your head around the tutorials available and the frameworks provided you can create high perfomance games. And also port them to other devices other than the iphone very easily which is quite cool.
Long Answer:
Quartz 2D
Quartz 2D is the powerful 2D graphics API for iOS. It offers professional-strength 2D graphics features such as Bézier curves, transformations, and gradients. Use Quartz 2D for custom interface elements to give a stylized look to your application.
Core Animation
Core Animation is likely the appropriate choice for games where performance is not critical such as simon says type games, card games, and trivia games. Some might argue that OpenGL ES is easier to use, and it likely is if you’ve studied say.. DirectX.. but Core Animation (and Quartz 2D for that matter) is much easier to do simple effects in, and can be used with existing UIViews.
Core Animation is fine for games where performance is not critical, and for new programmers will likely be easy to use, OpenGL is needed for anything else.
Core Animation utilizes OpenGL ES, it is high level, and in my testing works fine in situations where performance is critical.
OpenGL ES
is your choice for performance critical games. Which is essentially anything but simple mostly static games like the ones mentioned I above such as first person shooters, flight simulators and the like. You also get the added benefit of potentially being able to port your games to a device other than the iPhone, and there is alot of existing game code in OpenGL that can be converted the other way. OpenGL ES is an open standard that is used on a growing number of devices created by a wide variety of companies, and because CoreAnimation is a higher level framework built atop OpenGL ES it cannot provide nearly the same performance.
http://maniacdev.com/2009/07/iphone-game-programming-coreanimation-vs-opengl-es/
http://developer.apple.com/technologies/ios/graphics-and-animation.html
PK
I am going to develope the 2D game in Iphone using Quartz.
what is the main Difference between Quartz and QuartzCore?
I have searched a lot over the internet, but only able to find out the MAC OS with Quartz Examples.
If any body has any Link/URL for Examples of Quartz(2D) using Iphone Developement,which would be run in the Real Iphone Device?
Also if possible than give the Link for Bunch of examples/repository for Quartz Iphone.
Thanks,
Mishal Shah
I think you might be confusing a few things here. Quartz lets you do static 2-D vector drawing, but this is different from the QuartzCore framework, which you import into a project if you wish to use Core Animation. Core Animation is what you're looking for when it comes to 2-D animation on the Mac or iPhone (if you aren't going to go the way of OpenGL ES). You really do not want to use Quartz to redraw a moving scene, because you will get terrible display performance.
This does get confusing, because you can use Quartz to draw 2-D vector or raster art into UIViews or CALayers, and then animate those around using Core Animation. For a good introduction to Quartz, I recommend the Quartz 2D Programming Guide. For Core Animation, there is the Core Animation Programming Guide, as well as the Core Animation book by Bill Dudney.
You're right, there is a lot of sample code out there for Quartz on the Mac, as well as for Core Animation, but the nice thing is that Quartz and Core Animation use almost identical APIs on the Mac and iPhone. There are a few small differences, but for the most part code written for one runs on the other. As an example, we designed the Core Plot framework
around Core Animation, using Quartz drawing, because we can have an almost identical codebase between our Mac and iPhone versions of the framework. That's at least one large piece of sample code that you can look at.
Finally, Opacity is a really neat utility that lets you draw vector artwork and generate the Quartz drawing code to reproduce that artwork within your application. It's a great way to try things out.
There are a number of very nice Quartz2D and CoreAnimation animation examples in this project, from the 360iDev conference session on Core Animation:
http://github.com/neror/CA360
You should read the Quartz 2D Programming Guide. After reading the guide, take a look at QuartzDemo.
On an iPhone:
If I am writing a game that has multiple levels, with multiple animations (image sequences), jpg and png (transparent), some full screen and some not, some looped and some played once only. What is the best way of doing it? Each level might have up to 10MB of images. Add on to this music, and video (cut scenes). All 2D graphics, no 3D models.
Is OpenGL required? Or can this be achieved with Quartz or Core Animation?
I do similar using UIViews and a bit of Core Graphics (Quartz 2D) and it works fine. I've found the custom drawing in Core Graphics pushes it a bit further, tho - UIViews work best when given images rather than having to draw themselves. Also watch out for lots of transparencies. You'll probably find that large or long (many frame) animations will be the killer, though. There are some techniques for minimising the impact of the animations which involves allowing it to purge images from memory if not being immediately displayed (I forget the setting). This may result in your animations not being as smooth as you they would otherwise be (not sure if Open GL ES would help here, though).
You should probably prototype using UIViews, and decide then if it's worth doing the extra work for OpenGL ES. Also, if you're not already familiar with OpenGL/ Open GL ES it's a steep learning curve.
I've used both Quartz and OpenGL to do graphics on the iPhone, and while OpenGL has a much higher learning curve, it gives much better performance than Quartz. Let's say you have a scene that involves drawing 6 large, semi-transparent images on top of each other. Quartz will do it, but you'll probably get 15fps at best. OpenGL takes advantage of the iPhone's PowerVR chip and the drawing is hardware accelerated - so you can load those images into OpenGL textures and render at 25-30fps no problem.
I would agree with Phil though - try doing it using Quartz and see if it meets your needs. OpenGL is extremely powerful but it's API lacks some of the convenience features of Quartz (such as saving/restoring graphics state).
One another note entirely, you might want to take a look at Unity's iPhone development tools (http://unity3d.com/#iphone). They leverage OpenGL but provide you with an IDE to create your game. It abstracts away all of the graphics-level code, so you can focus on the high-level gameplay. My brother uses it to write iPhone games, and it's extremely cool.
I recommend having a look at Cocos2D iPhone.
cocos2d for iPhone is a framework for building 2D games, demos, and other graphical/interactive applications. It is based on the cocos2d design: it uses the same API, but instead of using python it uses objective-c.
Most likely OpenGl.
One advantage of using OpenGL ES would be that the investment of time for learning the technology could be applied to other platforms/contexts and your game is potentially more port-friendly. These may not be important to you.
I would suggest using Quartz. OpenGL ES is really best for 3d stuff. However both work fairly well, so if you already know OpenGL ES, it's fine to use that.
You should consider using a lot of less resources in your game, Apple recommends not to use more than 10 mb in texture for openGL apps.
Try texture atlas, reuse graphics, tile based graphics...but avoid to use to much graphic assets.
I've seen a lot of bandying about what's better, Quartz or OpenGL ES for 2D gaming. Neverminding libraries like Cocos2D, I'm curious if anyone can point to resources that teach using OpenGL ES as a 2D platform. I mean, are we really stating that learning 3D programming is worth a slight speed increase...or can it be learned from a 2D perspective?
GL is likely to give you better performance, with less CPU usage, battery drain, and so on. 2D drawing with GL is just like 3D drawing with GL, you just don't change the Z coordinate.
That being said, it's easier to write 2D drawing code with Quartz, so you have to decide the trade-off.
Cribbed from a similar answer I provided here:
You probably mean Core Animation when you say Quartz. Quartz handles static 2-D drawing within views or layers. On the iPhone, all Quartz drawing for display is done to a Core Animation layer, either directly or through a layer-backed view. Each time this drawing is performed, the layer is sent to the GPU to be cached. This re-caching is an expensive operation, so attempting to animate something by redrawing it each frame using Quartz results in terrible performance.
However, if you can split your graphics into sprites whose content doesn't change frequently, you can achieve very good performance using Core Animation. Each one of those sprites would be hosted in a Core Animation CALayer or UIKit UIView, and then animated about the screen. Because the layers are cached on the GPU, basically as textures, they can be moved around very smoothly. I've been able to move 50 translucent layers simultaneously at 60 FPS (100 at 30 FPS) on the original iPhone (not 3G S).
You can even do some rudimentary 3-D layout and animation using Core Animation, as I show in this sample application. However, you are limited to working with flat, rectangular structures (the layers).
If you need to do true 3-D work, or want to squeeze the last bit of performance out of the device, you'll want to look at OpenGL ES. However, OpenGL ES is nowhere near as easy to work with as Core Animation, so my recommendation has been to try Core Animation first and switch to OpenGL ES only if you can't do what you want. I've used both in my applications, and I greatly prefer working with Core Animation.