Wiley.Games.on.Symbian.OS.A.Handbook.for.Mobile.Development.Apr.2008 (779888), страница 52
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This saving is a major advantage interms of phone battery life alone. As well as that, your animations andgraphics will be that much smoother, and the processor cycles that aren’tbeing used for media calculations can then be put to better use (for morecomplex physics simulations and game AIs which will make your gamemore immersive).The games industry is already supporting the OpenKODE standardwith Softbank, a major wireless operator in Japan. The Khronos groupannounced in May 20073 that Softbank will be incorporating support forOpenKODE into the Portable Open Platform Initiative (POP-i) which willsupport major mobile operating systems including (but not limited to)Linux, Windows Mobile and of course Symbian OS.
Softbank became amember of the Khronos Group in August 2007.Even better from a game developer’s point of view is that Ideaworks3Dand Texas Instruments (TI) announced in March 2007 that TI’s OMAPPlatform4 will be extended to support the OpenKODE 1.0 specificationusing the Airplay SDK.5 And even better than that, it will scale for futurestandards such as OpenGL ES 2.0 (which will have support for shaders,and frankly that’s just going to be berserk).Leon Clarke from Ideaworks3D has this to say about the Airplay SDKand OpenKODE:‘‘The goal of the joint project with TI and Ideaworks3D is that developerscan start developing OpenKODE games using the Airplay SDK on top ofTI’s development boards, meaning that developers can start exploiting thefeatures of new versions of OMAP before they are integrated into realphones.
Because Airplay provides binary compatibility across a wide rangeof platforms and makes fanatical attempts to behave in the same way on allplatforms, when phones eventually arrive with the new OMAP platform,developers can expect their games to just run on the new device, evenif for some strange reason, the handset is running Windows Mobile orBREW instead of Symbian OS. Airplay also supports ARM’s RTSM real-timesimulator, allowing the actual ARM binary to be debugged in a source-leveldebugger on your desktop without even needing a device.
There’s also aWindows-native emulator allowing you to use the full capabilities of VisualStudio 2005’s debugger.3For more details, see the press release on the Khronos website: www.khronos.org/news/press/releases/softbank mobile adopts openkode to provide rich media accelerationor a related article at www.linuxdevices.com/news/NS5874940517.html.4For more information about the OMAP Platform, please see: focus.ti.com/general/docs/wtbu/wtbugencontent.tsp?templateId=6123&navigationId=11988&contentId=4638or search for OMAP from the main TI website at www.ti.com.5More information can be found in the Ideaworks3D press release at www3.ideaworks3d.com/downloads/Ideaworks3D-TI OpenKODE.pdf.OPENVG227The approach taken by Ideaworks3D to OpenKODE is slightly unusual,in that it is built on top of Airplay.
Ideaworks3D was very heavily involvedin the development of the OpenKODE standard, and a lot of their experience with Airplay (and what features games developers actually wantand need) helped shape OpenKODE, so the two are actually very similar in terms of functionality, so the OpenKODE layer is very thin. Thismeans that Ideaworks3D’s OpenKODE implementation can be expectedto behave identically across different underlying operating systems, whileother implementations will probably have variations in minor (but criticalif writing a high-end game) details like exactly how the heap behaves,what compiler bugs exist, and things like that.
Of course, the whole pointof OpenKODE is to provide source-level portability across different platforms, but realistically there will be a few quirks when moving betweendifferent OpenKODE implementations or between different platforms onOpenKODE implementations that try less hard to hide platform differences.Airplay was designed by game developers, so of course it runs as closeas possible to the hardware, letting you optimize for the exact platformyou’re running on and use all its capabilities, such as graphics hardware orfloating point hardware.
But if you want to write a single build that runsanywhere, you are free to do so.If anyone doesn’t like OpenKODE, Airplay also provides a more traditional set of POSIX libraries, complete with STL etc, with the addedadvantage that these will behave in exactly the same way across differentplatforms.’’Symbian continues to provide support for industry standards as partof its core offering. Symbian OS v9.5 will be OpenKODE 1.0 compliantbecause it will include a reference implementation of OpenGL ES 1.1.Prior to Symbian OS v9.5, only OpenGL ES 1.0 has been supplied,although OpenGL ES 1.1 is available as a plug-in to the S60 3rd Edition.Symbian OS v9.5 will also offer an implementation of OpenVG 1.01.SVGs are already supported by Symbian OS v9, it’s just that the implementation isn’t fully OpenVG compliant.
Offering full OpenVG compliancein Symbian OS v9.5 is a natural consequence of the platform’s continuingevolution.7.4 OpenVGThe OpenVG standard addresses the growing need in industry for highquality, scalable, hardware accelerated 2D vector graphics. It mainlytargets devices with small screens and low power budgets like mobilephones.With a drawing model very similar to other vector graphics technologies, OpenVG can provide acceleration for Flash, SVG, PDF and Postscriptdata and allows the creation of fast anti-aliased graphics that can be usedto create screensavers, GUIs and, of course, games. Furthermore, since228 C/C++ STANDARDS SUPPORT FOR GAMES DEVELOPERS ON SYMBIAN OSit is part of the OpenKODE suite, it is also royalty free (which is a bigwoo-hoo!).As of mid-2007, OpenVG is gaining a fast adoption rate particularly as its syntax is very similar to OpenGL ES, which makes it veryeasy for developers to learn and use.
Some of its core features includeblending, images, image filters, viewport clipping, scissoring, and alphamasking – which are familiar concepts to anyone who has worked withOpenGL or OpenGL ES before.The current version of the specification is 1.0.1 which dictates that anyimplementation must ‘‘support all drawing features required by a SVGTiny1.2 renderer .’’6The specification defines extensive requirements for Bezier curves, 2Dtransformations, painting and, like OpenGL ES, it uses EGL to acquiregraphics contexts and surface for rendering.As I mentioned at the end of the previous section, Symbian OS v9.5will be OpenVG 1.0.1 compliant as part of its OpenKODE support.7.5 OpenMAXThe OpenMAX standard defines cross-platform portability for streamingmedia such as audio and video codecs, to process a high throughputof data in a consistent manner.
It targets middleware developers whoproduce graphics libraries, multimedia codecs, and other functions forimage, video, audio, voice and speech.In the absence of such a standard, efforts to port existing solutionsacross platforms have generally been very expensive to date becauselarge amounts of the code base have to be optimized in platformspecific assembler (which sounds like lots of fun doesn’t it?). So theOpenMAX standard should provide a large cost benefit in the nearfuture.There are three flavors of the standard:• OpenMAX IL (integration layer): defines a standard low-level interfacefor multimedia codecs on mobile and embedded devices.
The mainaim here is to provide codecs with a system abstraction layer – theimplementation remains transparent to the client.• OpenMAX DL (development layer): defines an API for audio, videoand imaging functionality that hardware vendors can implement on6The OpenVG 1.0.1 Specification can be found at www.khronos.org/files/openvg 10 1.pdf. A reference implementation for Microsoft Windows is available at www.khronos.org/openvg.OPENSL ES229their processors and DSPs.
Codec vendors can use these as acceleratedbuilding blocks for their own codec implementations. The currentversion is 1.0.1.• OpenMAX AL (application layer): defines an application-levelmultimedia playback and recording API that provides for deviceindependent cross-platform access to a device’s audio, video andimaging capabilities. At the time of writing, this specification has justbeen released in its provisional form and is expected to be finalizedby 2008.OpenMAX is not currently part of OpenKODE 1.0, but will insteadform part of OpenKODE 1.1 to be finalized in 2008.
OpenMAX hasalready gained acceptance and is already supported in popular hardwaresuch as the Sony PlayStation 3 console.Symbian OS v9.5 will include audio and video codec interfaces thatare compliant with OpenMAX IL 1.0 and Symbian plans to supportOpenMAX AL in the future as well. This will provide a stepping stonetowards Symbian OS becoming a fully compliant OpenKODE 1.1 mobileoperating system.7.6 OpenSL ESThe OpenSL ES (Open Sound Library for Embedded Systems) is currently only at a provisional specification stage. The aim is to definean application-level enhanced audio API that includes features such asadvanced MIDI, 3D sound and audio effects.
It will be part of OpenKODE1.1 and I would hope that by this stage of the book, its relevance to mobilegame development should be clear to you!As Aleks has already covered this subject in detail in Chapter 4, I’llsay no more about it here other than to note that there is necessarily adegree of overlap between OpenSL ES and OpenMAX AL, specificallyin regards to audio playback, audio recording and basic MIDI. This isbecause OpenMAX AL focuses on media capture and rendering (whichincludes audio) while OpenSL ES focuses on audio functionality formobile devices.Symbian is committed to supporting these emerging standards in thefuture7 although it’s difficult to say when, since the specs aren’t finalizedyet.
This is kind of like trying to design a system when your client keeps7‘‘Symbian plans multimedia standards and bearer mobility’’ in Computer Business Review Online: www.cbronline.com/article news.asp?guid=193EEDF0-B8DE-4EF791 DB- 5ABA6027558F.230 C/C++ STANDARDS SUPPORT FOR GAMES DEVELOPERS ON SYMBIAN OSchanging their mind – you know you can provide what they want as soonas they decide just what that is!7.7 EGLThe Native Platform Graphics Interface (known as EGL) is an interfacebetween rendering APIs such as OpenGL ES or OpenVG and the underlying native platform windowing system. The latest version is EGL 1.3,although currently Symbian OS only has support for EGL 1.1.EGL handles context management, surface and buffer binding, and rendering synchronization, as well as mixed rendering where OpenGL ES andOpenVG can share a drawing surface.
The standard defines three typesof rendering surfaces – windows, pixmaps, and pixel buffers (pbuffers).Both windows and pixmaps are associated with native resources, whereaspbuffers are off-screen rendering surfaces used by EGL itself; rendering topbuffers via the native windowing system may not even be supported.Using EGL with OpenGL ES in Symbian OS C++ greatly simplifies andstandardizes the code needed to obtain a rendering context as comparedto achieving the same using CFbsBitmap.
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