smooth_random_generator.h
// Copyright 2016 Olivier Gillet.
//
// Author: Olivier Gillet (ol.gillet@gmail.com)
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
// 
// See http://creativecommons.org/licenses/MIT/ for more information.
//
// -----------------------------------------------------------------------------
//
// Smooth random generator for the internal modulations.

#ifndef PLAITS_DSP_NOISE_SMOOTH_RANDOM_GENERATOR_H_
#define PLAITS_DSP_NOISE_SMOOTH_RANDOM_GENERATOR_H_

#include "stmlib/stmlib.h"
#include "stmlib/utils/random.h"

namespace plaits {

class SmoothRandomGenerator {
 public:
  SmoothRandomGenerator() { }
  ~SmoothRandomGenerator() { }
  
  void Init() {
    phase_ = 0.0f;
    from_ = 0.0f;
    interval_ = 0.0f;
  }
  
  float Render(float frequency) {
    phase_ += frequency;
    if (phase_ >= 1.0f) {
      phase_ -= 1.0f;
      from_ += interval_;
      interval_ = stmlib::Random::GetFloat() * 2.0f - 1.0f - from_;
    }
    float t = phase_ * phase_ * (3.0f - 2.0f * phase_);
    return from_ + interval_ * t;
  }
  
 private:
  float phase_;
  float from_;
  float interval_;
  
  DISALLOW_COPY_AND_ASSIGN(SmoothRandomGenerator);
};

}  // namespace plaits

#endif  // PLAITS_DSP_NOISE_SMOOTH_RANDOM_GENERATOR_H_