Glenn Corpes on why iPhone 4 to 4S is a bigger upgrade for developers than iPhone 3G to 3GS

iPad 2 has changed the industry

Glenn Corpes on why iPhone 4 to 4S is a bigger upgrade for developers than iPhone 3G to 3GS
Having amassed one million pre-orders within its first 24 hours, it would appear consumers have just as much enthusiasm for iPhone 4S as they did its predecessor, if not more.

Developer reaction, however, appears to have been far cooler, and – in the viewpoint of British programmer Glenn Corpes – that's a mistake.

As detailed in an entry on Corpes' blog, those expecting more of iPhone 4S should compare what it represents as a transition from iPhone 4 to the leap made between iPhone 3G and 3GS.

New language

"I've read and heard that it is a far less significant upgrade from iPhone4 than 3GS was from 3G," opens Corpes.

"This is unarguably true in one way, 3G-3GS introduced OpenGLES2.0 and let us graphics coders start using shaders rather like they had been for years on computers and consoles. But what did the introduction of 3Gs mean to developers?"

Corpes argues that developers making the leap to 3GS needed to "rewrite everything" in ES2.0.

"ES2.0 has no built in transform stuff, lighting, a few missing renderstates.

"All stuff that now has to be done in the shader rather than through gl calls. Much much better but quite a bit of work to get an app to support GL1.1 and GL2.0 at the same time so, it seems to me, very few developers jumped straight on ES2.0."

Smooth landing

Now, however, the industry as moved on, and the addition of the 'nine times faster' iPad 2 means iPhone 4S is entering a world where developers are already on board with the tech.

The transition, Corpes claims, will be a far smoother one.

"I've heard people theorising about how Epic and Chair must have had early access to 4S to create the Infinity Blade 2 demo when, in reality, all they had to do was run the phone version with their very impressive iPad 2 enhancements," he concludes .

"I suspect there are hundreds of developers who were already including iPad 2 enhancements in upcoming apps, thousands who were thinking about it, the 4S is just another very good reason to bother with those bigger, cooler and more fun to write shaders.

"Support for 4S will be even easier for those using engines like Unity and Unreal, even if they aren't writing their own shaders, they will simply be able to select more interesting ones."

[source: Glenn Corpes]

With a fine eye for detail, Keith Andrew is fuelled by strong coffee, Kylie Minogue and the shapely curve of a san serif font.