audio filters moved to its own files

src/net/torvald/terrarum/audio/dsp/Highpass.kt

@@ -0,0 +1,50 @@
+package net.torvald.terrarum.audio.dsp
+
+import com.jme3.math.FastMath
+import net.torvald.terrarum.audio.TerrarumAudioMixerTrack
+
+class Highpass(cutoff0: Float): TerrarumAudioFilter() {
+
+    var cutoff = cutoff0.toDouble(); private set
+    private var alpha: Float = 0f
+
+    val in0 = FloatArray(2)
+    val out0 = FloatArray(2)
+
+    init {
+        setCutoff(cutoff0)
+    }
+
+    fun setCutoff(cutoff: Float) {
+//        println("LP Cutoff: $cutoff")
+        val RC: Float = 1f / (cutoff * FastMath.TWO_PI)
+        val dt: Float = 1f / TerrarumAudioMixerTrack.SAMPLING_RATEF
+        alpha = RC / (RC + dt)
+        this.cutoff = cutoff.toDouble()
+    }
+
+    fun setCutoff(cutoff: Double) {
+//        println("LP Cutoff: $cutoff")
+        val RC: Double = 1.0 / (cutoff * Math.PI * 2.0)
+        val dt: Double = 1.0 / TerrarumAudioMixerTrack.SAMPLING_RATEF
+        alpha = (RC / (RC + dt)).toFloat()
+        this.cutoff = cutoff
+    }
+
+    override fun thru(inbuf: List<FloatArray>, outbuf: List<FloatArray>) {
+        for (ch in outbuf.indices) {
+            val out = outbuf[ch]
+            val inn = inbuf[ch]
+
+            out[0] = alpha * (out0[ch] + inn[0] - in0[ch])
+
+            for (i in 1 until outbuf[ch].size) {
+                out[i] = alpha * (out[i-1] + inn[i] - inn[i-1])
+            }
+
+            out0[ch] = outbuf[ch].last()
+            in0[ch] = inbuf[ch].last()
+        }
+    }
+
+}