Oh man, I just wasted too many hours of my life trying to figure out why calls to glBlitFramebuffer in my iOS app were returning GL_INVALID_OPERATION. I was targeting iOS 7, so I should’ve been able to use OpenGL ES 3.0 calls, and after all, I’d built against the v3 headers and everything else was compiling and working… right?
Wrong. Well, I really should’ve RTFM. It turns out that ES 3.0 use is not determined just by the OS version, but by the hardware. So even if you’re running iOS 7, you can only use ES 3.0 if you’re on the latest gen: iPhone 5S, iPad Air etc. Check out the full compatibility matrix here.
Here are a few extra tips to help you avoid wasting your time like I did if you’re explicitly targeting OpenGL ES 3.0:
It’s pretty frustrating that you get no indication that the function’s not supported, as opposed to just having being passed bad state. But I guess that’s par-for-the-course with a bare-bones, down-to-the-metal API like Open GL.
On my recent iOS puzzler Wordz, I decided not to reinvent the wheel, and instead use an off-the-shelf 2d game framework. I settled on Cocos2d. It makes it very easy to put together sprite-based games or apps by providing all the basic pieces like a scene graph, animations and integration with a couple of physics engines. It’s built on OpenGL but, happily, hides all that away from you – unless you need it.
No sooner had I released it, than Apple came out and announced a new framework for 2d games: SpriteKit. And it’s remarkably similar to Cocos2d. Here I’ll take a look at a few places where they differ, so you know what to look out for if you’re considering migrating to SpriteKit.
Posted in Graphics, iOS, iPhone, Uncategorized
Tagged 2d, cocos2d, games, Graphics, iOS, OpenGL, SpriteKit, sprites
Screenshot of the finished lava lamp effect
Catchy title, eh? This little experiment came about as I’ve been working on an iOS app where I decided to use an embedded OpenGL view, via GLKit, for a bit more flexibility than a plain-old UIView. This found me falling head-first down a rabbit-hole of OpenGL ES shaders. I ended up putting together a little demo that emulates a lava lamp using a nifty bit of GLSL code.
Wow, it’s been a ridiculously long time since I’ve blogged. I think it’s time I put something up just to break the curse, and this seemed like a good, and hopefully useful, place to start. Time to polish some of these dusty drafts into published gems.
Ever been in that situation where you (or someone else) finds that Visual Studio just won’t set a breakpoint in some source code that you’re sure should be being used? You’ll see the hollow breakpoint icon and something like ‘The breakpoint will not currently be hit. No symbols have been loaded for this document’.
In the second of an unknown number of parts in my series of Beginning F# posts, I’ll be talking about record types. They’re a useful and powerful F# feature that you’ll probably find yourself using very widely. I’ll take a look at what they are, how they’re used and how they integrate with the rest of the language.
If, like me, you’re still squeezing yourself into 32-bit Windows processes, you’re probably, also like me, constantly keeping an eye on the virtual address space usage of your application. If you happen to have used something like vmmap to take a peek at your memory contents, maybe you’ve noticed something strange with some .NET assemblies: they’re loaded twice! What’s going on…?
The other day while I was looking through some of my ancient copies of Computer and Video Games magazine (“the first fun computer magazine!”) I discovered some coverage of the 1982 Consumer Electronics Show. It’s such a contrast to today’s shiny, immaculately produced, PR-fest that I couldn’t help but scan it in for everyone to see.
Warning: This is a bit off-topic for my blog, but I had to write it and get it off my chest.
In these times of financial woe, people love to complain about all the big, nasty, faceless companies avoiding paying tax. They inevitably moan about it on Facebook, Google and Twitter (and sometimes even do something about it in the real, physical, world). But what about those companies themselves? The Web 2.0 behemoths are now some of the largest companies in the world, and they’ve decided – just like the evil old companies – that they don’t like paying all that tax. Don’t be evil… and don’t pay any tax if you can help it. But how do they do it?