Add additive synth minim example (#231)

orx-jvm/orx-minim/README.md

@@ -6,10 +6,14 @@ A minimal Minim support library
 
 Add `orx-minim` to `orxFeatures`
 
-Check the [example](src/demo/kotlin/DemoFFT01.kt)
+Check the examples:
+
+* [FFT visualization of live audio input](src/demo/kotlin/DemoFFT01.kt)
+* [Additive synthesizer](src/demo/kotlin/DemoAdditive01.kt)
 
 ## Further reading
 
  * [Minim website](https://code.compartmental.net/tools/minim/)
+ * [Minim's UGens](https://code.compartmental.net/minim/index_ugens.html)
  * [Minim Github](https://github.com/ddf/Minim)
  * [Minim Processing examples](https://github.com/ddf/Minim/tree/master/examples)

orx-jvm/orx-minim/src/demo/kotlin/DemoAdditive01.kt

@@ -0,0 +1,104 @@
+import ddf.minim.ugens.Oscil
+import ddf.minim.ugens.Pan
+import org.openrndr.application
+import org.openrndr.color.rgb
+import org.openrndr.extra.minim.minim
+import org.openrndr.math.Polar
+import kotlin.math.pow
+import kotlin.random.Random
+
+/**
+ * Random drone generator and visualizer with 20 stereo voices.
+ * Hold the mouse button to randomize the frequencies.
+ * Press keys 'a' or 'b' for less random frequencies.
+ */
+fun main() {
+    application {
+        program {
+            val minim = minim()
+            val out = minim.lineOut
+
+            // generates a random frequency value biased down
+            fun randomFreq() = 20f + Random.nextFloat().pow(3) * 1000
+
+            // If one didn't want to visualize or control the synths we
+            // wouldn't need a data structure to store them. Here we store
+            // Pairs, so we have access both to the frequency of the wave
+            // and the current amplitude defined by the lfo (low frequency
+            // oscillator).
+            val synths = List(20) {
+                // By default Oscil creates sine waves, but it can be changed.
+                val lfo = Oscil(
+                    Random.nextFloat() * 0.1f + 0.005f,
+                    0.05f
+                ).apply {
+                    // Here we set the center of the lfo to 0.05f.
+                    // Since the amplitude is also 0.05f, it moves between
+                    // 0.00f and 0.10f.
+                    offset.lastValue = 0.05f
+
+                    // Have the sine waves to not start in sync.
+                    //phase.lastValue = Random.nextFloat() * 6.28f
+                }
+                val wave = Oscil(randomFreq(), 0f)
+                // The `lfo` Oscil controls the `wave` Oscil's amplitude.
+                lfo.patch(wave.amplitude)
+                // Random pan to avoid a mono sound.
+                val pan = Pan(Random.nextFloat() * 2 - 1)
+                wave.patch(pan)
+                pan.patch(out)
+                // Store a [Pair] in `synths`.
+                Pair(wave, lfo)
+            }
+            val bgColor = rgb(0.094, 0.188, 0.349)
+            val lineColor = rgb(0.992, 0.918, 0.671)
+
+            extend {
+                drawer.clear(bgColor)
+                drawer.translate(drawer.bounds.center)
+                drawer.rotate(seconds)
+                // A CircleBatchBuilder for faster drawing of circles.
+                drawer.circles {
+                    // For each synth draw a circle.
+                    synths.forEachIndexed { i, (wave, lfo) ->
+                        stroke = lineColor.opacify(Random.nextDouble(0.4) + 0.6)
+                        fill = lineColor.opacify(Random.nextDouble() * 0.04)
+                        // A Polar arrangement centered on the screen.
+                        // Higher pitch circles are farther away from the center.
+                        val pos = Polar(
+                            360.0 * i / synths.size,
+                            50.0 + wave.frequency.lastValue * 0.2
+                        ).cartesian
+                        // The size of the circle depends on the current volume
+                        // set by the lfo.
+                        circle(pos, 500 * lfo.lastValues.last().toDouble())
+                    }
+                }
+                if (mouse.pressedButtons.isNotEmpty()) {
+                    synths.random().first.setFrequency(randomFreq())
+                }
+            }
+            keyboard.keyDown.listen { key ->
+                when (key.name) {
+                    "a" -> {
+                        // make all frequencies close to a base frequency
+                        // (circular arrangement)
+                        val baseFreq = 20 + Random.nextFloat() * 200
+                        synths.forEach {
+                            it.first.setFrequency(baseFreq + Random.nextFloat() * 20)
+                        }
+                    }
+
+                    "b" -> {
+                        // make all frequencies follow an exponential series
+                        // (spiral arrangement)
+                        val inc = Random.nextFloat() * 0.1f
+                        synths.forEachIndexed { i, (wave, _) ->
+                            wave.setFrequency(25f.pow(1f + i * inc))
+                        }
+                    }
+                }
+            }
+        }
+    }
+}