Add orx-time-operators with Envelope & LFO

orx-time-operators/src/main/kotlin/LFO.kt

@@ -0,0 +1,60 @@
+package org.openrndr.extra.timeoperators
+
+import org.openrndr.math.clamp
+import org.openrndr.math.mod
+import kotlin.math.*
+
+internal const val TAU = 2.0 * PI
+
+// TODO: When there's a @DropdownParameter switch from Int to String
+enum class LFOWave(val wave: Int) {
+    SAW(0), SINE(1), SQUARE(2), TRIANGLE(3)
+}
+
+@Suppress("UNUSED")
+class LFO(var wave: LFOWave = LFOWave.SAW) : TimeTools {
+    private var current = 0.0
+        set(value) {
+            field = clamp(value, 0.0, 1.0)
+        }
+
+    private var initialTime = Double.NEGATIVE_INFINITY
+    private var dt = 0.0
+    private var time = 0.0
+
+    override fun tick(seconds: Double, deltaTime: Double, frameCount: Int) {
+        time += deltaTime
+    }
+
+    fun sample(frequency: Double = 1.0, phase: Double = 0.0): Double {
+        return when(wave) {
+            LFOWave.SAW -> saw(frequency, phase)
+            LFOWave.SINE -> sine(frequency, phase)
+            LFOWave.SQUARE -> square(frequency, phase)
+            LFOWave.TRIANGLE -> triangle(frequency, phase)
+        }
+    }
+
+    fun saw(frequency: Double = 1.0, phase: Double = 0.0): Double {
+        val cycleFreq = 1.0 / frequency
+        val cycleTime = mod(time + (phase * frequency), cycleFreq)
+        current = (cycleTime) / cycleFreq
+        return current
+    }
+
+    fun sine(frequency: Double = 1.0, phase: Double = 0.0): Double {
+        current = sin((phase * TAU) + time * frequency * TAU) * 0.5 + 0.5
+        return current
+    }
+
+    fun square(frequency: Double = 1.0, phase: Double = 0.0): Double {
+        current = max(sign(sin((phase * TAU) + time * frequency * TAU)), 0.0)
+        return current
+    }
+
+    fun triangle(frequency: Double = 1.0, phase: Double = 0.0): Double {
+        val t = (time * frequency) + (phase * frequency)
+        current = 1.0 - 2.0 * abs(mod(t, 1.0) - 0.5)
+        return current
+    }
+}