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jango
04-08-2009, 12:07 PM
Hi,
I'm into iPhone Development recently and I'm studying OpenGLES for knowledge.

I'd like know if anyone can help me with fundamentals and do's and don'ts.
If I could get a bit of background for it, that would be very helpful.

Here's what I know so far about it:

OpenGL® ES is a royalty-free, cross-platform API for full-function 2D and 3D graphics on embedded systems - including consoles, phones, appliances and vehicles. It consists of well-defined subsets of desktop OpenGL, creating a flexible and powerful low-level interface between software and graphics acceleration. OpenGL ES includes profiles for floating-point and fixed-point systems and the EGL™ specification for portably binding to native windowing systems. OpenGL ES 1.X is for fixed function hardware and offers acceleration, image quality and performance.
In terms of my use in the Apple iPhone Technology : OpenGL ES framework offers a compact and efficient subset of the OpenGL API for 2D and 3D drawing on mobile devices. The OpenGL ES framework includes EAGL, a C-based API that supports the integration of OpenGL ES rendering with Core Animation layers and UIKit views. You can also use EAGL to render to pixel buffers.

OpenGL ES 2.X enables full programmable 3D graphics.

I'm reading from a book and some tutorials as well.
Your input to this post will be valued.
I will be updating this post regularly.

Thanks,
D

Thanks

scratt
04-09-2009, 01:58 AM
Some info for you..
http://www.khronos.org/opengles/sdk/1.1/docs/man/

iPhone at present is OpenGLES 1.1 only.

Apple's Documentation is obviously invaluable, and pretty good.
http://developer.apple.com/iphone/librar...07072-CH10-SW27 (http://developer.apple.com/iphone/library/documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/GraphicsandDrawing/GraphicsandDrawing.html#//apple_ref/doc/uid/TP40007072-CH10-SW27)

There's sample code too..
http://developer.apple.com/iphone/library/navigation/Frameworks/Media/OpenGLES/index.html

Bottom line is to remember, as with any mobile device, horsepower, bandwidth *and* space are low compared to desktop machines.

Pre-define as much data as you can.
Initialise as much as you can at startup.
Re-use as much as you can during run-time.

Be nice to your battery.

Some Specs..
http://www.glbenchmark.com/phonedetails.jsp?benchmark=pro&D=Apple%20iPhone&testgroup=gl

And if you want to have a good overview then go to the GPU manufacturers website and learn about the different rendering method used by this flavour of mobile GPU.
It has significant implications for how you should use the pipeline, specifically things like and kind of texture access you do during a re-draw. A lot of that stuff is also touched on in Apple's own documentation.

jango
04-09-2009, 11:27 AM
@ scratt

Thanks.
Your help is appreciated.
I'm reading the tutorials... and will be starting the development soon.

cheers.

D

jango
04-10-2009, 03:01 AM
http://iphonesdkdev.blogspot.com/2009/04/opengl-es-for-iphone-simple-tutorial.html

this tutorial is also a good one to start with Open GLES