Max (and its open source counterpart, PD) is a powerful environment for experimenting with sound and music. We use one of our own learning supplements, a Max patcher for generating scales (3.1.4), as an example of the kinds of programs you can write.
When you open this patcher, it is in presentation mode (Figure 3.47), as indicated by the drop-down menu in the bottom right corner. In presentation mode, the patcher is laid out in a user-friendly format, showing only the parts of the interface that you need in order to run the tutorial, which in this case allows you to generate major and minor scales in any key you choose. You can change to programming mode (Figure 3.48) by choosing this option from the drop-down menu.
Programming mode reveals more of the Max objects used in the program. You can now see that the scale-type menu is connected to a list object. This list changes in accordance with the selection, each time giving the number of semitones between consecutive notes on the chosen type of scale. You can also see that the program is implemented with a number of send, receive, and patcher objects. Send and receive objects pass data between them, as the names imply. Objects named s followed by an argument, as in s notepitch, are the send objects. Objects named r followed by an argument, as in r notepitch, are the receive objects. Patcher objects are “subpatchers” within the main program, their details hidden so that the main patcher is more readable. You can open a patcher object in programming mode by double-clicking on it. The metronome, handlescale, and handlenote patcher objects are open in Figure 3.49, Figure 3.50, and Figure 3.51.
In this example, you still can’t see the details of how messages are being received and processed. To do so, you have to unlock the main patcher window by clicking the lock icon in the bottom left corner. This puts you in a mode where you can inspect and even edit objects. The main patcher is unlocked in Figure 3.52. You must have the full Max application, not just the runtime, to go into full programming mode.
With all the patcher objects exposed and the main patcher unlocked, you can now see how the program is initialized and how the user is able to trigger the sending and receiving of messages by selecting from a menu, turning the dial to set a tempo, and clicking the mouse on the keyboard display. Here’s how the program runs:
- The loadbang object is triggered when the program begins. It is used to initialize the tempo to 120 bpm and to set the default MIDI output device. Both of these can be changed by the user.
- The user can select a type of scale from a menu. The list of intervals is set accordingly and sent in the variable scalesintervals, to be received by the handlescale patcher object.
- The user can select a tempo through the dial object. The input value is sent to the metronome patcher object to determine the timing of the notes played in the scale.
- The user can click a key on the keyboard object. This initiates the playing of a scale by sending a keyhit message to both the metronome and the handlescale patcher.
- When the metronome patcher receives the keyhit message, it begins sending a tick every n milliseconds. The value of n is calculated based on the bpm value. Each tick of the metronome is what Max calls a bang message, which is used to trigger buttons and set actions in motion. In this case, the bang sets off a counter in the handlescale patcher, which counts out the correct number of notes as it plays a scale. The number of notes to play for a given type of scale is determined by a lookup list in the zl object, a multipurpose list processing object.
- The pitch of the note is determined by setting the keynote to the correct one and then accumulating offsets from there. As the correct notepitch is set for each successive note, it is sent to the handlenote patcher, which makes a MIDI message from this information and outputs the MIDI note. To understand this part of the patcher completely, you need to know a little bit about MIDI messages, which we don’t cover in detail until Chapter 6. It suffices for now to understand that middle C is sent as a number message with the value 60. Thus, a C major scale starting on middle C is created from the MIDI notes 60, 62, 64, 65, 67, 69, 71, and 72.
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Max has many types of built-in objects with specialized functions. We’ve given you a quick overview of some of them in this example. However, as a beginning Max programmer, you can’t always tell from looking at an object in programming mode just what type of object it is and how it functions. To determine the types of objects and look more closely at the implementation, you need to unlock the patcher, as shown in Figure 3.52. Then if you select an object and right click on it, you get a menu that tells the type of object at the top. In the example in Figure 3.53, the object is a kslider. From the context menu, you can choose to see the Help or an Inspector associated with the object. To see the full array of Max built-in objects, go to Max Help from the main Help menu, and from there to Object by Function.
