Under the Bridge

So, you serious about improving your Open GL code for the desktop or Open GL ES code for the iPhone? Really serious? Like, “$1000? Pffft! A BARGAIN!” serious?

Well, have we got the tool for you: gDEBugger!

gDEBugger does what no other OpenGL tool can – lets you trace application activity on top of the OpenGL API to see what‘s happening within the graphic system implementation. gDEBugger saves you time by locating “hard-to-find” bugs caused by the incorrect use of the OpenGL API. Debugging OpenGL applications is faster and your applications are more reliable.

gDEBugger provides you with the application behavior information you need for optimizing application performance. No more redundant or “performance killer” OpenGL calls.

Also, you can perform regression tests to understand changes in visual display, performance and accuracy between different versions of your OpenGL application…

Indeed. We’d seen this tool mentioned before on the mac-0pengl list, so when we saw news of an iPhone beta, we signed right up for it. And indeed, once you get past the flaky Windowsness of the port, it is a most uniquely functional tool. Check out the tutorial and this article on optimization which is part of the extensive online help.So that’s all very well, and it’s apparently popular, but how does it actually run? Well, we ran it over the very early shell of a little iPhone program we’re working on here, and here’s what it looks like at work:

That’s some pretty detailed information, huh? And on the right there is a sample of the kind of thing it finds for you; apparently we’re calling glGetIntegerv somewhere or other, and it politely tells us

Using “Get” or “Is” functions slows down render performance. These commands force the graphic system to execute all queued OpenGL calls before it can answer the “Get” or “Is” query.

Instead, consider caching relevant state variable values inside your application’s code.

Isn’t that helpful? Learn a new thing every day, yes indeed!

So we would suggest that you should all go out and add it to your toolset immediately if you’re doing any OpenGL work, being uniquely suited to that … but $1000-odd with the maintenance package whatever that is, that’s kinda on the steep side if you’re not actually optimization bound at this exact moment, isn’t it? But we shall see what price point they actually release it at soon enough apparently, the release version is scheduled for sometime in July apparently. And July is close!