I recently pushed a significant set of changes to the GPUImage repository,, and wanted to explain them in a little more detail, especially since this changes one part of the manual photo filtering process. These changes should dramatically reduce the overall memory usage of the framework, help to prevent memory-related crashes, and fix a number of subtle bugs that have plagued the framework since I started it.

With the launch of iOS 7, and its use of blurs throughout the interface, there's been a lot of interest in fast ways of blurring content. GPUImage has had a reasonably performant, but somewhat limited Gaussian blur implementation for a while, but I've not been happy with it. I've completely rewritten this Gaussian blur, and it now supports arbitrary blur radii while still being tuned for the iOS GPUs. At higher blur radii, I'm slower than Core Image, though, and I don't quite understand why.

The 2.0 version of Molecules brings with it a brand new rendering engine that utilizes OpenGL ES 2.0 to deliver realistic 3-D representations of molecular structures. This is a long way from the original OpenGL ES 1.1 renderer that I first wrote about here, so I want to describe in detail how this new version works. The source code for Molecules is available under the BSD license, so you are free to download the project from the main application page and follow along as I walk through the process.

I've been invited to give a talk at the SecondConf developer conference in Chicago, and I'm writing this to accompany it. I'll be talking about using the GPU to accelerate processing of video on Mac and iOS. The slides for this talk are available here. The source code samples used in this talk will be linked throughout this article. Additionally, I'll refer to the course I teach on advanced iPhone development, which can be found on iTunes U here.

I've been doing a lot of work with Core Animation lately during development of my next iPhone application, and I came across an interesting way to optimize OpenGL ES rendering that I thought I'd share. This small improvement yielded a 14-25% increase in the triangles per second I was able to push in Molecules.

I had a great time at the satellite iPhoneDevCamp in Chicago, where I was surprised with the number of well-known (to me, at least) developers who are located in the area. Although the San Francisco outpost may have had more attendees, I'd argue that we had as good a technical and business discussion going. We certainly had better shirts (courtesy of Stand Alone).