I’m not smart enough to program my own patches for QC, but I was able to build a Cocoa application that sends the data from the sensors to the QC composition. I got a little help from the Phidget Interface Kit -sample code that you can download here and from the instructions found from the Phidgets forum. The code on the forum post didn’t work for me so here’s a small tutorial that shows you how build a Cocoa app that will control your Quartz Composer composition with Phidgets sensors.

What do you need?

- A computer running Mac OSX 10.4 with the developer tools installed
- Phidgets Interface Kit 8/8/8 + some sensors
- Download and install the Mac OSX Framework 21 from Phidgets website. This will also include the source code that you need for this tutorial.

OK. Let’s start

1)
Open the CocoaIFKit Xcode project from the /Examples/Source Code/CocoaIFKit folder.

2)
First we need to modify the project so that we can import and use a Quartz Composer Composition. These next steps are explained with more detail in the Quartz Composer programming guide by Apple and I recommend that you try the tutorials first, but I’ll go through the important stuff quickly.

- First, choose Project > Add to Project.
- Navigate to System/Library/Frameworks/Quartz.framework and add it to the project.
- Drag the Quartz.Framework to your Frameworks folder in the Groups & Files list
- Double click the MainMenu.nib file and Interface Builder launches.
- If you haven’t done this before, you have to install the Quart Composer palette to Interface Builder. Choose Tools > Palettes > Palette Preferences and click add.
- Navigate to /Developer/Extras/Palettes/ and add QuartzComposer.palette.
- Now your palette window should show the Quartz Composer palette. The blue thing is QCView and the green thing is QCPatchController.

- Drag the QCPatchController from the Palette window to the Instances tab in the MainMenu.nib window
- Go to the Cocoa Windows tab in the Palette window and drag a window to the Instances tab also. A new window appears.
- Your MainMenu.nib window should look something like this

- Select the new window and go to Tools > Show Inspector. In the Attributes section, make sure that the “Visible at launch time” is checked for the new window
- Now drag a QCView from the palette to the new window and resize the QCView the way you like it.
- Select the QCView and then open the Bindings pane of the Inspector window. Click the small triangle where it says patch.
- Choose QCPatchController from the “Bind to” pop-up menu. Enter patch in the Controller Key text field.

3)
OK. Now we need a QC Composition to use with our app. I won’t go to any details about using Quartz Composer. There’s plenty of info for that available and this tutorial is already becoming too long.

What you need to do is to create any kind of composition that has a published input with the name of sensorZero. I just used an Image With String connected to a Sprite and published the String input with the name sensorZero. Save the .qtz file to the CocoaIFKit folder. I used the name phidgets.qtz.

Back in Xcode, drag phidgets.qtz to the Resources folder in the Groups & Files list. In Interface Builder, select the QCPatchCotroller from the MainMenu.nib window and select the Attributes pane of the Inspector and click “Load from Composition File…” Navigate to your phidgets.qtz file. Choose File > Test Interface. You should see your composition in the window. The sensors won’t work in the testing mode.

4)
Now the application shows our composition, but we want to change the published value with the sensors. Read on and I’ll tell you how to do just that.

- Select the blue PhidgetInterfaceKitController from the instances tab. Then select the classes tab.
- Choose Classes > Add Outlet to PhidgetInterfaceKitController.
- Name the new outlet theController
- In the Instances tab, ctrl-click and drag from the PhidgetInterfaceKitController to the QCPatchController

- Choose Connect to connect the outlet.
- Save and go to Xcode again.

5)
Now we need to change the code so that the data goes from the sensors to the QC composition

- Double-click the PhidgetInterfaceKitController.h file.
- Add this to the list of outlets:

IBOutlet id theController;

- Close the window and double-click the PhidgetInterfaceKitController.m file.
- Find the SensorChange section and add this code there:

// sensors to Quartz Composer
if(Index==0){
[theController setValue:[NSNumber numberWithInt:(int)Value] forKeyPath:@”patch.sensorZero.value”];
}else if(Index==1){
[theController setValue:[NSNumber numberWithInt:(int)Value] forKeyPath:@”patch.sensorOne.value”];
}else if(Index==2){
[theController setValue:[NSNumber numberWithInt:(int)Value] forKeyPath:@”patch.sensorTwo.value”];
}else if(Index==3){
[theController setValue:[NSNumber numberWithInt:(int)Value] forKeyPath:@”patch.sensorThree.value”];
}else if(Index==4){
[theController setValue:[NSNumber numberWithInt:(int)Value] forKeyPath:@”patch.sensorFour.value”];
}else if(Index==5){
[theController setValue:[NSNumber numberWithInt:(int)Value] forKeyPath:@”patch.sensorFive.value”];
}else if(Index==6){
[theController setValue:[NSNumber numberWithInt:(int)Value] forKeyPath:@”patch.sensorSix.value”];
}else if(Index==7){
[theController setValue:[NSNumber numberWithInt:(int)Value] forKeyPath:@”patch.sensorSeven.value”];
}

- We only published the sensorZero from QC, but this code works with all the 8 analog inputs in the Interface Kit (Index numbers 0-7). So you can publish more values from QC. Just name them correctly: sensorZero, sensorOne, sensorTwo…
- Note! I’m a total amateur when it comes to Cocoa, so this code might not be the best way to do this but it works.

6)
That’s it. Save. Then choose Build and Go to see if it works.

If you want to change the QC composition, you need to reload the composition to the QCPatchController in Interface Builder and rebuild the app.

Pheew! This is the first tutorial I’ve ever written. I hope it’s useful to someone.