Category Archives: Apps

Spectral Harp Out Now For iOS

Image showing the Spectral Harp app.

Spectral Harp is now available on the iOS App Store for just $0.99!

Spectral Harp is a sound toy that generates sound by letting you strum or tap strings that represent portions of the audible spectrum. You can produce more variations in sound by using the four sliders along the bottom to control spectrum density, pitch, decay, and a bit crush effect. It’s great for creating things that sound like aliens or droids talking. Here’s a sound sample:

WaveShaper Update and Sale!

Another bug-fix update will be going out on the store later tonight or tomorrow and to celebrate I’m dropping the price to $1.99 for one day. If you’ve been reluctant to spend the full $6 on it, grab it on January 28th!

Also coming reasonably soon will be version 2.0, which will include Dropbox integration and Audio Copy/Paste.

Auto-rotation in iOS with openFrameworks

I don’t think that I’ve mentioned this before, but WaveShaper is a mixture of openFrameworks, UIKit, and Minim for C++. One of the major difficulties I’ve had in developing the app is getting the UIKit views and controllers to play nice. It’s not hard to render UIKit widgets on top of the EAGLView, you simply add your UIKit widget as a subview of the UIWindow or the EAGLView that openFrameworks creates, but it does not work to directly use openFrameworks coordinates to set the position and size of UIKit widgets.

The reason it doesn’t work is because (I’m pretty sure) openGL’s coordinate system is not the same as Apple’s. Part of what openFrameworks does is translate the coordinates of incoming touches from Apple’s coordinate system to openGL’s before sending touch events. This allows you to always think about the drawing surface in the “natural” way for doing openGL apps: upper left corner is always (0,0), positive X is to the right, positive Y is down. You can use this knowledge to simply transform your openGL coordinates to Apple coordinates when setting the position and size of UIKit widgets, but if you are using ofxiPhoneSetOrientation to reorient your openGL surface, the mapping between openGL coordinates and UIKit coordinates changes depending on the orientation. This means you have to reposition all of your UIKit objects every time the device is reoriented. Even worse, what I discovered is that in one of the landscape modes, even though the UIKit widgets looked correct, I actually had the device orientation set to the opposite of what it should have been, so when I displayed popovers, they were upside-down. When I presented modal view controllers, they would appear in the correct orientation, but then not rotate when device orientation changed.

After much hair-pulling, I finally came up with a solution that I think is pretty solid. Essentially, what I have done is embed the EAGLView in a view hierarchy that is well behaved with respect to Apple’s system and I do not call ofxiPhoneSetOrientation to change the orientation of the app. What this means is that from openFrameworks’ perspective the app never changes orientation, which is true in some sense because the EAGLView is added as a subview to a vanilla UIView that is strictly responsible for handling the rotation.

Ok, onto some actual code. Before setting up any UI, I set the openFrameworks orientation to landscape:

Then I rearrange the view hierarchy that openFrameworks creates so that I can set the position and size of UIKit widgets using openFrameworks coordinates. Included in this is creating a root view controller for the window, so that I can take advantage of the auto-rotation behavior they provide (and because Apple expects your app to have a root view controller):

Here’s the LandscapeViewController class, which limits supported orientations to landscape orientations and also turns off animations during rotation so that the orientation snaps. If you like the animated orientation change, you can simply remove those lines.

Finally, the class that registers to receive ofxiPhoneAlerts needs to handle device orientation changes like this:

And again, WaveShaper only displays in landscape, which is why those are the only orientations I handle.

Once all of this is in place, you can happily position buttons, sliders, popovers, and whatever else using the openFrameworks coordinate system and they will all look correct and rotate with the screen.

WaveShaper 1.1: bug fix update coming soon!

I’ve been seeing several reports of WaveShaper crashing a lot and after spending some time looking into it, I’m pretty sure I’ve fixed the problem. It wasn’t a crash, per se, but actually a lock up in the audio system, which caused the OS to kill the app. Sometimes this could happen on start up and sometimes when attempting to preview files in the file list.

The update should be available on December 30th. This is later than I’d like it to be available, but the iTunes Connect holiday shutdown began today and lasts through the 29th.

My sincerest apologies to all who have bought the app and experienced these crashes.

WaveShaper for iPad Released!

Today I released my first sound making app for iPad!

WaveShaper is an app for iPad that allows you to load up any audio file and make crazy cool sounds with it. It’s a lot like record scratching, but totally maxed out. This video will do a much better job of explaining it than words ever will:

Visit for more info, sound samples, and screenshots. Or just go buy it right now!