Add AllPass class example

Author: kevinstadler

content/references/examples/sound/AllPass/AllPass_0.pde

@@ -0,0 +1,38 @@
+import processing.sound.*;
+
+SawOsc saw;
+AllPass allPass;
+
+void setup() {
+  size(512,360);
+  background(255);
+  
+  // Create a sawtooth wave and an AllPass filter
+  saw = new SawOsc(this);
+  saw.freq(200);
+  allPass = new AllPass(this);
+  
+  // Start the saw wave and push it through the allpass
+  saw.play();
+  allPass.process(saw);
+}
+
+void draw() {
+  background(0);
+  
+  // Set the drive of the allPass with the mouse
+  float g = map(mouseX, 0, width, 0., 1);
+  allPass.gain(g);
+  
+  // Draw some visuals for intuition
+  float a = 50;
+  strokeWeight(4);
+  for (float i = 0; i < width; i = i + 3) {
+    // Draw a wave
+    stroke(255, 0, 0);
+    point(i, sin(i) * a + width/2);
+    // Draw that wave again after being driven by g
+    stroke(0, 255, 0);
+    point(i + g * TWO_PI, a * sin(i) + width/2);
+  }
+}