PivotField.h

/*
 * PivotField.h
 *
 * (c) 2025 Sofian Audry        :: info(@)sofianaudry(.)com
 * (c) 2018 Thomas O Fredericks :: tof(@)t-o-f(.)info
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#ifndef PIVOT_FIELD_H_
#define PIVOT_FIELD_H_
 
#include "AbstractField.h"
#include "pq_easing.h"
 
namespace pq {
 
enum PivotFieldMode {
  PIVOT_RISING,
  PIVOT_FALLING,
  PIVOT_BUMP,
  PIVOT_NOTCH
};
 
class PivotField : public AbstractField
{
public:
  PivotField();
  virtual ~PivotField() {}
 
  virtual float at(float proportion) override;
 
  virtual float get() override { return _value; }
 
  virtual float put(float value) override {
    return (_value = constrain01(value));
  }
 
  void mode(PivotFieldMode mode) { _mode = mode; }
 
  PivotFieldMode mode() const { return _mode; }
 
  void easing(easing_function easing) { _easing = easing; }
 
  void noEasing() { easing(easeNone); }
 
  void rampWidth(float rampWidth);
 
  void noRampWidth() { rampWidth(0); }
 
  float rampWidth() const { return _rampWidth; }
 
  void rampShift(float rampShift);
 
  float rampShift() const { return _rampShift; }
 
  void bumpWidth(float bumpWidth);
 
  float bumpWidth() const { return 2*_halfBumpWidth; }
 
  void center(float center) { _center = constrain01(center); }
 
  float center() const { return _center; }
 
protected:
  // Internal use: return ramp value based on proportion compared to value.
  float _ramp(float proportion, float value) {
    return
#if PQ_OPTIMIZE_FOR_CPU
      constrain01( (proportion - value) * _invRampWidth + _rampShiftFactor );
#else
      constrain01( (proportion - value) / _rampWidth - 2*_rampShift + 1.5f );
#endif
  }
 
protected:
  // The current mode.
  PivotFieldMode _mode;
 
  // The current value.
  float _value;
 
  // The ramp width as %.
  float _rampWidth;
 
  // The ramp shift in [0, 1].
  float _rampShift;
 
  // The bump width as %.
  float _halfBumpWidth;
 
  // The center of the ramp in [0, 1].
  float _center;
 
  // Optional easing function.
  easing_function _easing;
 
#if PQ_OPTIMIZE_FOR_CPU
  // Precompiled values.
  float _invRampWidth;
  float _rampShiftFactor;
#endif
};
 
}
#endif