Port vco.js to vco.lua.

examples/vco.js

@@ -1,7 +1,7 @@
 // Voltage-controlled oscillator example
 // by Andrew Belt
 
-// JavaScript isn't ideal for audio generating and processing due to it being 10-100 less efficient than C++, but it's still an easy way to learn simple DSP.
+// For audio synthesis and process, JavaScript is 10-100x less efficient than C++, but it's still an easy way to learn to program DSP.
 
 config.frameDivider = 1
 config.bufferSize = 16
@@ -11,6 +11,7 @@ function process(block) {
 	// Knob ranges from -5 to 5 octaves
 	let pitch = block.knobs[0] * 10 - 5
 	// Input follows 1V/oct standard
+	// Take the first input's first buffer value
 	pitch += block.inputs[0][0]
 
 	// The relationship between 1V/oct pitch and frequency is `freq = 2^pitch`.

examples/vco.lua

@@ -0,0 +1,34 @@
+-- Voltage-controlled oscillator example
+-- by Andrew Belt
+
+-- For audio synthesis and process, Lua is 10-100x less efficient than C++, but it's still an easy way to learn to program DSP.
+
+config.frameDivider = 1
+config.bufferSize = 16
+
+phase = 0
+function process(block)
+	-- Knob ranges from -5 to 5 octaves
+	pitch = block.knobs[1] * 10 - 5
+	-- Input follows 1V/oct standard
+	-- Take the first input's first buffer value
+	pitch = pitch + block.inputs[1][1]
+
+	-- The relationship between 1V/oct pitch and frequency is `freq = 2^pitch`.
+	-- Default frequency is middle C (C4) in Hz.
+	-- https://vcvrack.com/manual/VoltageStandards.html#pitch-and-frequencies
+	freq = 261.6256 * math.pow(2, pitch)
+	display("Freq: " .. string.format("%.3f", freq) .. " Hz")
+
+	-- Set all samples in output buffer
+	deltaPhase = config.frameDivider * block.sampleTime * freq
+	for i=1,block.bufferSize do
+		-- Accumulate phase
+		phase = phase + deltaPhase
+		-- Wrap phase around range [0, 1]
+		phase = phase % 1
+
+		-- Convert phase to sine output
+		block.outputs[1][i] = math.sin(2 * math.pi * phase) * 5
+	end
+end