Inspired by Nodebox, propane (copied from ruby-processing) provides a way to control the instance variables of your sketch with a control panel. You can create sliders, buttons, menus and checkboxes that set instance variables on your sketch. Since ruby-processing-2.0 you need to explicitly set the panel visible from the processing sketch (see included examples). Start by loading in the control_panel library, and then define your panel like so:- NB: revised version for propane-2.7.2+

Simple Buttons Example

require 'propane'

class SimpleButton < Processing::App
  load_library :control_panel

  attr_reader :back

  def setup
    sketch_title 'Simple Button'
    control_panel do |c|
      c.look_feel 'Nimbus'
      c.title 'Control Button'
      c.button :color_background # needs a defined :color_background method
      c.button :exit { exit } # button with optional block
    end
    color_mode RGB, 1
    @back = [0, 0, 1.0]
  end

  def color_background
    @back = [rand, rand, rand]
  end

  def draw
    background *back
  end

  def settings
    size 300, 300
  end
end

SimpleButton.new

More Complete Example


require 'propane'

class ControlPanelExample < Processing::App
  load_library :control_panel

  def settings
    size(200, 200)
  end

  def setup
    sketch_title 'Control Panel Example'
    control_panel do |c|
      c.look_feel "Nimbus"
      c.slider :opacity
      c.slider(:app_width, 5..60, 20) { reset! } # see reset! method
      c.menu(:options, ['one', 'two', 'three'], 'two') { |m| load_menu_item(m) }
      c.checkbox :paused
      c.button :reset!
    end
  end

  def draw
  # Rest of the code follows
  end

  # eg
  def reset!
    # some action you want performed on button pressed
  end
end

ControlPanelExample.new

This code will create a sketch with a control panel for adjusting the value of the @opacity, @app_width, @options, and @paused instance variables. The button will call the reset! method when clicked (a method defined by you in your sketch). The app_width slider will range from 5 to 60 instead of (the default) 0 to 100. The instance variable will be initialized at 20 when the sketch is loaded. The app_width and options controls have had callbacks attached to them. The callbacks will run, passing in the value of the control, any time the control changes. It all looks like this:

control panel

Here is the classic ruby-processing JWishy sketch translated for propane, basically you enter the control_panel items in a block, to experiment just add a single item at a time and check that it works (eg :button or :checkbox)

Start by loading in the control_panel library, and then define your panel in setup like so:

require 'propane'

class JWishy < Propane::App
  load_library :control_panel
  attr_reader :panel

  def settings
    size 600, 600
  end

  def setup
    sketch_title 'Wishy Worm'
    control_panel do |c|
      c.title 'Control Panel'
      c.look_feel 'Nimbus'
      c.slider    :bluish, 0.0..1.0, 0.5
      c.slider    :alpha,  0.0..1.0, 0.5
      c.checkbox  :go_big
      c.button    :reset
      c.menu      :shape, %w(oval square triangle)
    end
    @hide = false
    @shape = 'oval'
    @go_big = false
    @x_wiggle, @y_wiggle = 10.0, 0
    @magnitude = 8.15
    @back_color = [0.06, 0.03, 0.18]
    color_mode RGB, 1
    ellipse_mode CORNER
    smooth
  end

  #....rest of code

  def draw
    #.... rest of draw
  end

JWishy

See also penrose and bezier playground sketches. See ruby code here.