Oscillator Experiment

Oscillator.cs

using UnityEngine;
using System;
using System.Diagnostics;
using System.Threading;

// http://www.codeproject.com/Articles/30180/Simple-Signal-Generator
// http://blogs.msdn.com/b/dawate/archive/2009/06/25/intro-to-audio-programming-part-4-algorithms-for-different-sound-waves-in-c.aspx

class Oscilator : MonoBehaviour {

  public enum Type { SINE, SQUARE, TRIANGLE, SAWTOOTH };
  public float amplitude = 1.0f;
  public float frequency = 1.0f;
  public float phase     = 0.0f;
  public float offset    = 0.0f;
  public int invert      = 1; // 1, -1
  public Type type = Type.SINE;
  
  private long startTime = Stopwatch.GetTimestamp();
  private long ticksPerSecond = Stopwatch.Frequency;
  
  private float GetTime() {
    return (float)(Stopwatch.GetTimestamp() - startTime) / ticksPerSecond;
  }
  
  public void Reset() {
    startTime = Stopwatch.GetTimestamp();
  }
  
  void OnAudioFilterRead(float[] data, int channels) {
    for (int i = 0; i < data.Length; i = i + channels) {
      float value = 0f;
      float t = frequency * GetTime() + phase;
      switch (type) {
        case Type.SINE:
          value = (float)Math.Sin(2f * Math.PI * t);
          break;
        case Type.SQUARE:
          value = Math.Sign(Math.Sin(2f * Math.PI * t));
          break;
        case Type.TRIANGLE:
          value = 1f - 4f * (float)Math.Abs(Math.Round(t - 0.25f) - (t - 0.25f));
          break;
        case Type.SAWTOOTH:
          value = 2f * (t - (float)Math.Floor(t + 0.5f));
          break;
      }

      data[i] = (invert * amplitude * value + offset);
      if (channels == 2) data[i + 1] = data[i];
    }
  }
  
}