edit hacking.md

oregano/Hacking.md

@@ -5,7 +5,7 @@
 ## Goal
 I planned on writing a client for the SuperCollider (SC) music synthesis server for use in the Music Programming section of CSC123. Using the interface to SuperCollider, students will have access to real-time synthesis techniques.
 
-## First hope
+## Initial steps
 In the first quarter, after examining implementations in various languages, I set out on creating a new implementation in Racket from scratch. Quickly, however, it appeared that two quarters is not enough time, so I looked into porting the scheme implementation of a supercollider client, rsc3, to Racket.
 
 ### The Porting process
@@ -24,27 +24,45 @@ One tricky part was a difference in the list representations between r6rs scheme
 
 ## Features added
 
-It would be hard for first year students to use rsc3 directly, so I created simplified functions to perform common tasks of creating and controlling sounds.
+It would be hard for first year students to use rsc3 directly, so I created simplified abstractions (functions and structures) to perform common tasks of creating and controlling sounds.
 
 ### Instruments
 
 
-One main feature of SuperCollider is the Synthdef.
+Students could create instruments with parameters that could be changed in real-time. Students can use this defined instruments to play notes
+
+I used a Racket macro to create the instrument creation form.
+
+An instrument corresponds to a Synhtdef in SuperCollider. A Synthedef is a composition of functions called ugens. ugens, which stands for unit generator,
+
+Instruments are associated with functions that play notes. A note contains the instrument name and frequency. The functions can turn on a note, turn it off, and change some instrument parameters, which will only affect the playing note, while the note is playing.
+
+### GUI elements to control parameters
+
+One interesting feature I implemented is the ability to easily create GUI elements to control note parameters. Currently there is a slider and checkbox. The slider works by passing a label, start value, end, initial, values, and a callback function that accepts the value of the slider.
+
+While this uses a lambda function, it could be easily changed to accept a particular note and the parameter string to change.
+
+I also added a slider funciton that can be used directly in the definition of an instrument. This encourages experimentation with parameter values.
+
+
+### Filters
+
+I added functions that can be used to chain effects, such as reverb and low pass filters. An effect added after a previous effect will act on the output of the previus effect. To implement this, I originally planned on chaining nodes using SuperCollider's audio buses. However, I found a ugen that could do that called replace-out that provides this functionality. That is, replace-out can read, modify, and write to the same bus.
+
+
+## Cross platform issues
+
+SuperCollider has versions for Windows, Linux and OS X. On Windows and OS X, SuperCollider doesn't need dependencies, but on Linux, SuperCollider requires a Jack server to be running. Students will have to install Jack, which is a different procedure depending on their Linux distribution. It's one line in a terminal on a Debian based distribution such as Ubuntu.
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-Students could create instruments with parameters that could be changed in real-time.
 
 
-## Outline
 
-- scratch & porting rsc3
-  - how I started
-  - challenges
-
-- features
-  - instruments
-  - sliders
-  - effect chaining
-
-- cross platform