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  1. //EaseIn = Start slow, accelerate to the goal.
  2. //EaseOut = Start fast, decelerate to the goal.
  3. //EaseInOut = Start slow, accelerate to the half-way point, decelerate to the goal.
  4. //EaseOutIn = Start fast, decelerate to the half-way point, accelerate to the goal.
  5. enum EaseStyle {EaseIn, EaseOut, EaseInOut, EaseOutIn};
  6.  
  7.  
  8. /*
  9.     Easer is an Easing/Tweening/Interpolating functor class.
  10.     You can either use the EaseEquations stand-alone, or pass them to Easer if you want
  11.     persistent data (perhaps holding Easer as a member-variable of another class).
  12. */
  13. class Easer
  14. {
  15. public:
  16.     Easer(EaseFunction easeFunction, EaseStyle style = EaseIn) : EaseFunc(easeFunction), Style(style) { }
  17.     ~Easer() = default;
  18.  
  19.     EaseStyle Style = EaseIn;
  20.     EaseFunction EaseFunc;
  21.  
  22.     //Used to constrain the return result to the desired range, such as 0.0f - 1.0f.
  23.     //The default setting is (-FLT_MAX, FLT_MAX). Note: For some funky reason, FLT_MIN is "the minimum positive value above zero". =/
  24.     FloatRange Constaints = FloatRange(-FLT_MAX, FLT_MAX);
  25.  
  26.     //The current position.
  27.     float Position = 0.0f;
  28.  
  29. public:
  30.     //Sets 'position' to 'newPosition'.
  31.     void SetPosition(float position);
  32.     //Resets 'position' to 0.0f. This is the same as calling SetPosition(0.0f);
  33.     void Reset();
  34.  
  35.     //Returns true if 'position' is at or beyond 1.0f.
  36.     bool AtEnd() const;
  37.  
  38.     //Returns the value at the current position.
  39.     //(Note: Unless constrained, the actual result may actually drop below 0.0f or above 1.0f depending
  40.     //on the easing function. This is intentional, and desirable for some effects)
  41.     float Get() const;
  42.     //Returns the value at the current position, scaled to the range of 'min' to 'max' instead of around (0.0f - 1.0f)-ish
  43.     float GetInRange(const FloatRange &range) const;
  44.  
  45.     //Returns the value at 'pos'.
  46.     float GetAt(float pos) const;
  47.     //Returns the value at 'pos', scaled to the range of 'min' to 'max' instead of around (0.0f - 1.0f)-ish
  48.     float GetInRangeAt(float pos, const FloatRange &range) const;
  49.  
  50.     //Moves the position of the ease by 'amount'.
  51.     void Step(float amount);
  52.  
  53.     void operator+=(float amount); //Same as Step().
  54.     void operator-=(float amount); //Same as Step() with a negative amount.
  55.     void operator=(float position); //Same as SetPosition().
  56.  
  57.     float operator()() const; //Same as Get()
  58.     float operator()(float value) const; //Same as GetAt()
  59.  
  60. private:
  61.     //Calls the callback function 'EaseFunc' and processes the result depending on the EaseStyle,
  62.     //then constrains the result using 'Constaints'. 
  63.     float plot(float position) const;
  64. };
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https://ideone.com/NedmuM
language:
C++ (gcc 8.3)
created:
11 years ago
visibility:
public

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