palladium/include/pd/maths/tween.hpp

#pragma once

/*
MIT License
Copyright (c) 2024 - 2025 René Amthor (tobid7)

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.
 */

#include <pd/maths/vec.hpp>

namespace PD {
template <typename T>
class Tween {
 public:
  enum Effect {
    Linear,
    EaseInQuad,
    EaseOutQuad,
    EaseInOutQuad,
    EaseInCubic,
    EaseOutCubic,
    EaseInOutCubic,
    EaseInSine,
    EaseOutSine,
    EaseInOutSine,
  };
  Tween() {}
  ~Tween() {}

  void Update(float delta) {
    time += delta / 1000.f;
    if (time > tend) {
      finished = true;
      time = tend;
    }
  }

  bool IsFinished() const { return finished; }

  Tween& Finish() {
    time = tend;
    finished = true;
    return *this;
  }

  Tween& From(const T& start) {
    Reset();
    this->start = start;
    return *this;
  }
  Tween& To(const T& end) {
    Reset();
    this->end = end;
    return *this;
  }
  Tween& In(float seconds) {
    Reset();
    tend = seconds;
    return *this;
  }
  Tween& As(const Effect& e) {
    effect = e;
    return *this;
  }
  Tween& Reset() {
    finished = false;
    time = 0.f;
    return *this;
  }
  /// @brief Probably usefull for fading colors by animation
  /// Used to create this caus dont wanted to create a
  /// fade effect fpr keyboard without having to Tween functions
  /// @return
  float Progress() const { return time / tend; }

  Tween& Swap() {
    T temp = start;
    start = end;
    end = temp;
    return *this;
  }

  operator T() {
    float t = 0.f;
    switch (effect) {
      case EaseInQuad:
        t = time / tend;
        return (end - start) * t * t + start;
        break;
      case EaseOutQuad:
        t = time / tend;
        return -(end - start) * t * (t - 2) + start;
        break;
      case EaseInOutQuad:
        t = time / (tend / 2);
        if (t < 1) return (end - start) / 2 * t * t + start;
        t--;
        return -(end - start) / 2 * (t * (t - 2) - 1) + start;
        break;
      case EaseInCubic:
        t = time / tend;
        return (end - start) * t * t * t + start;
        break;
      case EaseOutCubic:
        t = time / tend;
        t--;
        return (end - start) * (t * t * t + 1) + start;
        break;
      // case EaseInOutCubic:
      //   t = time / (tend / 2);
      //   if (t < 1) return (end - start) / 2 * t * t * t + start;
      //   t--;
      //   return (end - start) / 2 * (t * t * t * 2) + start;
      //   break;
      case EaseInSine:
        return -(end - start) * cos(time / tend * (M_PI / 2)) + (end - start) +
               start;
        break;
      case EaseOutSine:
        return (end - start) * sin(time / tend * (M_PI / 2)) + start;
        break;
      case EaseInOutSine:
        return -(end - start) / 2 * (cos(M_PI * time / tend) - 1) + start;
        break;

      default:  // Linear
        return (end - start) * (time / tend) + start;
        break;
    }
  }

 private:
  Effect effect;
  float time = 0.f;
  // Defaulting to one to prevent div zero
  // without a safetey check
  // not implementing one cause if the user is
  // Writing a In(0.f) its their fault
  float tend = 1.f;
  T start;
  T end;
  bool finished = false;
};
}  // namespace PD