Drum Machine

Author: monkstone

external_library/java/minim/data/BD.wav

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+# frozen_string_literal: true
+
+require 'picrate'
+# This sketch is a more involved use of AudioSamples to create a simple drum machine.
+# Click on the buttons to toggle them on and off. The buttons that are on will trigger
+# samples when the beat marker passes over their column. You can change the tempo by
+# clicking in the BPM box and dragging the mouse up and down.
+# We achieve the timing by using AudioOutput's playNote method and a cleverly written Instrument.
+# For more information about Minim and additional features,
+# visit http://code.compartmental.net/minim/
+class DrumMachine < Processing::App
+  load_libraries :minim, :tick
+  java_import 'ddf.minim.Minim'
+  java_import 'ddf.minim.ugens.Sampler'
+
+  attr_reader :minim, :out, :kick, :snare, :hat, :bpm, :beat, :buttons
+  attr_reader :kikRow, :snrRow, :hatRow
+  def setup
+    minim = Minim.new(self)
+    @out   = minim.getLineOut
+    @hatRow = Array.new(16, false)
+    @snrRow = Array.new(16, false)
+    @kikRow = Array.new(16, false)
+    @buttons = []
+    @bpm = 120
+    @beat = 0
+    # load all of our samples, using 4 voices for each.
+    # this will help ensure we have enough voices to handle even
+    # very fast tempos.
+    kick = Sampler.new(data_path('BD.wav'), 4, minim)
+    snare = Sampler.new(data_path('SD.wav'), 4, minim)
+    hat   = Sampler.new(data_path('CHH.wav'), 4, minim)
+
+    # patch samplers to the output
+    kick.patch(out)
+    snare.patch(out)
+    hat.patch(out)
+    16.times do |i|
+      buttons << Rect.new(10 + i * 24, 50, hatRow, i)
+      buttons << Rect.new(10 + i * 24, 100, snrRow, i)
+      buttons << Rect.new(10 + i * 24, 150, kikRow, i)
+    end
+    # start the sequencer
+    out.setTempo(bpm)
+    out.playNote(0, 0.25, Tick.new)
+  end
+
+  def draw
+    background(0)
+    fill(255)
+    # text(frameRate, width - 60, 20)
+
+    buttons.each(&:draw)
+
+    stroke(128)
+    (beat % 4).zero? ? fill(200, 0, 0) : fill(0, 200, 0)
+
+    # beat marker
+    rect(10 + beat * 24, 35, 14, 9)
+  end
+
+  def mouse_pressed
+    buttons.each(&:mouse_pressed)
+  end
+
+  def settings
+    size(395, 200)
+  end
+end
+
+DrumMachine.new

external_library/java/minim/data/CHH.wav

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+# frozen_string_literal: true
+
+# simple class for drawing the gui
+class Rect
+  include Processing::Proxy
+  attr_reader :x, :y, :w, :h, :steps, :stepId
+
+  def initialize(_x, _y, _steps, _id)
+    @x = _x
+    @y = _y
+    @w = 14
+    @h = 30
+    @steps = _steps
+    @stepId = _id
+  end
+
+  def draw
+    steps[stepId] ? fill(0, 255, 0) : fill(255, 0, 0)
+    rect(x, y, w, h)
+  end
+
+  def mouse_pressed
+    if mouseX >= x && mouseX <= x + w && mouseY >= y && mouseY <= y + h
+      steps[stepId] = !steps[stepId]
+    end
+  end
+end

external_library/java/minim/drum_machine.rb

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+# frozen_string_literal: true
+
+java_import 'ddf.minim.ugens.Instrument'
+
+class Tick
+  include Instrument
+  include Processing::Proxy
+
+  def noteOn(_dur)
+    hat.trigger if hatRow[beat]
+    snare.trigger if snrRow[beat]
+    kick.trigger if kikRow[beat]
+  end
+
+  def noteOff
+    # next beat
+    @beat = (beat + 1) % 16
+    # set the new tempo
+    out.setTempo(bpm)
+    # play this again right now, with a sixteenth note duration
+    out.playNote(0, 0.25, self)
+  end
+end

external_library/java/minim/library/tick/lib/rect.rb

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+require_relative 'lib/tick'
+require_relative 'lib/rect'