llinterp.h

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#ifndef LL_LLINTERP_H
#define LL_LLINTERP_H

#include "math.h"

// Class from which different types of interpolators can be derived

class LLInterpVal
{
public:
        virtual ~LLInterpVal() {}
        virtual void interp(LLInterpVal &target, const F32 frac); // Linear interpolation for each type
};

template <typename Type>
class LLInterp
{
public:
        LLInterp();
        virtual ~LLInterp() {}

        virtual void start();
        void update(const F32 time);
        const Type &getCurVal() const;

        void setStartVal(const Type &start_val);
        const Type &getStartVal() const;

        void setEndVal(const Type &target_val);
        const Type &getEndVal() const;

        void setStartTime(const F32 time);
        F32 getStartTime() const;

        void setEndTime(const F32 time);
        F32 getEndTime() const;

        BOOL isActive() const;
        BOOL isDone() const;
        
protected:
        F32 mStartTime;
        F32 mEndTime;
        F32 mDuration;
        BOOL mActive;
        BOOL mDone;

        Type mStartVal;
        Type mEndVal;

        F32 mCurTime;
        Type mCurVal;
};

template <typename Type>
class LLInterpLinear : public LLInterp<Type>
{
public:
        /*virtual*/ void start();
        void update(const F32 time);
        F32 getCurFrac() const;
protected:
        F32 mCurFrac;
};

template <typename Type>
class LLInterpExp : public LLInterpLinear<Type>
{
public:
        void update(const F32 time);
protected:
};

template <typename Type>
class LLInterpAttractor : public LLInterp<Type>
{
public:
        LLInterpAttractor();
        /*virtual*/ void start();
        void setStartVel(const Type &vel);
        void setForce(const F32 force);
        void update(const F32 time);
protected:
        F32 mForce;
        Type mStartVel;
        Type mVelocity;
};

template <typename Type>
class LLInterpFunc : public LLInterp<Type>
{
public:
        LLInterpFunc();
        void update(const F32 time);

        void setFunc(Type (*)(const F32, void *data), void *data);
protected:
        Type (*mFunc)(const F32 time, void *data);
        void *mData;
};


//
// Implementation
//
//

//
// LLInterp base class implementation
//

template <typename Type>
LLInterp<Type>::LLInterp()
{
        mStartTime = 0.f;
        mEndTime = 1.f;
        mDuration = 1.f;
        mCurTime = 0.f;
        mDone = FALSE;
        mActive = FALSE;
}

template <class Type>
void LLInterp<Type>::setStartVal(const Type &start_val)
{
        mStartVal = start_val;
}

template <class Type>
void LLInterp<Type>::start()
{
        mCurVal = mStartVal;
        mCurTime = mStartTime;
        mDone = FALSE;
        mActive = FALSE;
}

template <class Type>
const Type &LLInterp<Type>::getStartVal() const
{
        return mStartVal;
}

template <class Type>
void LLInterp<Type>::setEndVal(const Type &end_val)
{
        mEndVal = end_val;
}

template <class Type>
const Type &LLInterp<Type>::getEndVal() const
{
        return mEndVal;
}

template <class Type>
const Type &LLInterp<Type>::getCurVal() const
{
        return mCurVal;
}


template <class Type>
void LLInterp<Type>::setStartTime(const F32 start_time)
{
        mStartTime = start_time;
        mDuration = mEndTime - mStartTime;
}

template <class Type>
F32 LLInterp<Type>::getStartTime() const
{
        return mStartTime;
}


template <class Type>
void LLInterp<Type>::setEndTime(const F32 end_time)
{
        mEndTime = end_time;
        mDuration = mEndTime - mStartTime;
}


template <class Type>
F32 LLInterp<Type>::getEndTime() const
{
        return mEndTime;
}


template <class Type>
BOOL LLInterp<Type>::isDone() const
{
        return mDone;
}

template <class Type>
BOOL LLInterp<Type>::isActive() const
{
        return mActive;
}

//
// LLInterpLinear derived class implementation.
//
template <typename Type>
void LLInterpLinear<Type>::start()
{
        LLInterp<Type>::start();
        mCurFrac = 0.f;
}

template <typename Type>
void LLInterpLinear<Type>::update(const F32 time)
{
        F32 target_frac = (time - this->mStartTime) / this->mDuration;
        F32 dfrac = target_frac - this->mCurFrac;
        if (target_frac >= 0.f)
        {
                this->mActive = TRUE;
        }
        
        if (target_frac > 1.f)
        {
                this->mCurVal = this->mEndVal;
                this->mCurFrac = 1.f;
                this->mCurTime = time;
                this->mDone = TRUE;
                return;
        }

        target_frac = llmin(1.f, target_frac);
        target_frac = llmax(0.f, target_frac);

        if (dfrac >= 0.f)
        {
                F32 total_frac = 1.f - this->mCurFrac;
                F32 inc_frac = dfrac / total_frac;
                this->mCurVal = inc_frac * this->mEndVal + (1.f - inc_frac) * this->mCurVal;
                this->mCurTime = time;
        }
        else
        {
                F32 total_frac = this->mCurFrac - 1.f;
                F32 inc_frac = dfrac / total_frac;
                this->mCurVal = inc_frac * this->mStartVal + (1.f - inc_frac) * this->mCurVal;
                this->mCurTime = time;
        }
        mCurFrac = target_frac;
}

template <class Type>
F32 LLInterpLinear<Type>::getCurFrac() const
{
        return mCurFrac;
}


//
// LLInterpAttractor derived class implementation.
//


template <class Type>
LLInterpAttractor<Type>::LLInterpAttractor() : LLInterp<Type>()
{
        mForce = 0.1f;
        mVelocity *= 0.f;
        mStartVel *= 0.f;
}

template <class Type>
void LLInterpAttractor<Type>::start()
{
        LLInterp<Type>::start();
        mVelocity = mStartVel;
}


template <class Type>
void LLInterpAttractor<Type>::setStartVel(const Type &vel)
{
        mStartVel = vel;
}

template <class Type>
void LLInterpAttractor<Type>::setForce(const F32 force)
{
        mForce = force;
}

template <class Type>
void LLInterpAttractor<Type>::update(const F32 time)
{
        if (time > this->mStartTime)
        {
                this->mActive = TRUE;
        }
        else
        {
                return;
        }
        if (time > this->mEndTime)
        {
                this->mDone = TRUE;
                return;
        }

        F32 dt = time - this->mCurTime;
        Type dist_val = this->mEndVal - this->mCurVal;
        Type dv = 0.5*dt*dt*this->mForce*dist_val;
        this->mVelocity += dv;
        this->mCurVal += this->mVelocity * dt;
        this->mCurTime = time;
}


//
// LLInterpFucn derived class implementation.
//


template <class Type>
LLInterpFunc<Type>::LLInterpFunc() : LLInterp<Type>()
{
        mFunc = NULL;
        mData = NULL;
}

template <class Type>
void LLInterpFunc<Type>::setFunc(Type (*func)(const F32, void *data), void *data)
{
        mFunc = func;
        mData = data;
}

template <class Type>
void LLInterpFunc<Type>::update(const F32 time)
{
        if (time > this->mStartTime)
        {
                this->mActive = TRUE;
        }
        else
        {
                return;
        }
        if (time > this->mEndTime)
        {
                this->mDone = TRUE;
                return;
        }

        this->mCurVal = (*mFunc)(time - this->mStartTime, mData);
        this->mCurTime = time;
}

//
// LLInterpExp derived class implementation.
//

template <class Type>
void LLInterpExp<Type>::update(const F32 time)
{
        F32 target_frac = (time - this->mStartTime) / this->mDuration;
        if (target_frac >= 0.f)
        {
                this->mActive = TRUE;
        }
        
        if (target_frac > 1.f)
        {
                this->mCurVal = this->mEndVal;
                this->mCurFrac = 1.f;
                this->mCurTime = time;
                this->mDone = TRUE;
                return;
        }

        this->mCurFrac = 1.f - (F32)(exp(-2.f*target_frac));
        this->mCurVal = this->mStartVal + this->mCurFrac * (this->mEndVal - this->mStartVal);
        this->mCurTime = time;
}

#endif // LL_LLINTERP_H

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