Grain
- builds a signal path, plays a sound for a time period
  and then disconnects the nodes in the signal path

  - master context, cloud gain node passed in
  - grain buffer source node created from buffer
  - envelope node created (gain node)
  - panner node created
  - source node connect to panner node
  - panner node connect to envelope gain node
  - envelope gain node connect to cloud gain node

Cloud
- periodically creates a grain of a certain length & other params
  - sound resource passed in
  - set of grains
  - grain parameters
    - density -> rate of new grain creation
    - position -> relative waveform position
    - jitter -> random waveform position offset
    - spread -> random pan amount (default center)
    - length -> length of grain (including attack & release)
    - attack -> initial volume ramp
    - release -> final volume ramp
    - trans -> grain pitch

Zone
- cloud of grains is toggled via user gps relative to zone center gps
  - cloud params passed in
  - center: gps center of circle, relative to user-initialized map 'center'
  - radius: radius of circle boundary
  - distance: meters from user-initialized map 'center'
  - heading: direction to center from user-initialized map 'center'
  - occupied: boolean usable for UI interests (show title of all occupied zones)
  - registers gps event handler
    - new gps coords checks if it should start/stop cloud's grains
  - manages cloud play state
    - playing (unplayable)
    - stopped (ready)

TODO:

    Control Signals
      √ % of the screen is an x/y touch pad
      √ alpha, beta, gamma of accelerometer to grain length, pan, grain density
      gps long/lat changes file position
      proximity to center of zone toggles zone's cloud

    Audio
      create or choose sounds for each zone
      define various cloud configs for each zone



one sound - gps position changes grain window




sound for each