Specifications

5.6 Common abstraction techniques 53

my-tabosc2 640 0 my-tabosc2 1280 1 my-tabosc2 1920 0

pd grapha

ﬁg 5.11: Three diﬀerent wavefor ms and frequencies from the same table oscillator abstraction

SECTION 5.6

Common abstraction techniques

Here are a few tricks r e gularly used with abstrac tions and subpatches. With

these you can create neat a nd tidy patches and manage large projects made of

reusable ge neral components.

Graph On Parent

It’s easy to build nice looking interfaces in Pd using GUI components like sliders

and buttons. As a rule it is best to collect all interfa c e components for an

application together in one place and send the values to where they are needed

deeper within subpatches. At some point it’s necessary to expose the interface

to the user, so that when an object is created it a ppea rs with a selection of GUI

components laid out in a nea t way.

Clobber

Ooomph

Knarleyness

pd hardsynth

inlet midi note

ﬁg 5.12: Graph on parent synth

“Graph on Parent” (or GOP) is a proper ty of

the canvas which lets you see inside from out-

side the object box. Normal objects like os-

cillators are not visible, but GUI components,

including graphs are. GOP abstractions can be

nested, so that controls exposed in one abstrac-

tion are visible in a hig her abstraction if it is

also set to be GOP. In Fig. 5.12 we see a subpatch which is a MIDI synthesiser

with three controls. We have added three slider s and connected them to the

synth. Now we want to make this abstraction, called GOP-hardsynth, into a

GOP abstraction that reveals the controls. Click anywhere on a blank part of

the canvas, choose properties and activa te the GOP toggle button. A frame

will appear in the middle of the canvas. In the canvas properties box, set the

size to width = 140 and height = 80, which will nicely frame thre e standard size

sliders with a little border. Move the sliders into the frame, save the abstraction

and exit.