Modified source engine (2017) developed by valve and leaked in 2020. Not for commercial purporses
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//========= Copyright Valve Corporation, All rights reserved. ============//
//
// Purpose:
//
//=============================================================================//
#ifndef LERP_FUNCTIONS_H
#define LERP_FUNCTIONS_H
#ifdef _WIN32
#pragma once
#endif
template <class T>
inline T LoopingLerp( float flPercent, T flFrom, T flTo )
{
T s = flTo * flPercent + flFrom * (1.0f - flPercent);
return s;
}
template <>
inline float LoopingLerp( float flPercent, float flFrom, float flTo )
{
if ( fabs( flTo - flFrom ) >= 0.5f )
{
if (flFrom < flTo)
flFrom += 1.0f;
else
flTo += 1.0f;
}
float s = flTo * flPercent + flFrom * (1.0f - flPercent);
s = s - (int)(s);
if (s < 0.0f)
s = s + 1.0f;
return s;
}
template <class T>
inline T Lerp_Hermite( float t, const T& p0, const T& p1, const T& p2 )
{
T d1 = p1 - p0;
T d2 = p2 - p1;
T output;
float tSqr = t*t;
float tCube = t*tSqr;
output = p1 * (2*tCube-3*tSqr+1);
output += p2 * (-2*tCube+3*tSqr);
output += d1 * (tCube-2*tSqr+t);
output += d2 * (tCube-tSqr);
return output;
}
template <class T>
inline T Derivative_Hermite( float t, const T& p0, const T& p1, const T& p2 )
{
T d1 = p1 - p0;
T d2 = p2 - p1;
T output;
float tSqr = t*t;
output = p1 * (6*tSqr - 6*t);
output += p2 * (-6*tSqr + 6*t);
output += d1 * (3*tSqr - 4*t + 1);
output += d2 * (3*tSqr - 2*t);
return output;
}
inline void Lerp_Clamp( int val )
{
}
inline void Lerp_Clamp( float val )
{
}
inline void Lerp_Clamp( const Vector &val )
{
}
inline void Lerp_Clamp( const QAngle &val )
{
}
// If we have a range checked var, then we can clamp to its limits.
template< class T, int minValue, int maxValue, int startValue >
inline void Lerp_Clamp( CRangeCheckedVar<T,minValue,maxValue,startValue> &val )
{
val.Clamp();
}
template<>
inline QAngle Lerp_Hermite<QAngle>( float t, const QAngle& p0, const QAngle& p1, const QAngle& p2 )
{
// Can't do hermite with QAngles, get discontinuities, just do a regular interpolation
return Lerp( t, p1, p2 );
}
template <class T>
inline T LoopingLerp_Hermite( float t, T p0, T p1, T p2 )
{
return Lerp_Hermite( t, p0, p1, p2 );
}
template <>
inline float LoopingLerp_Hermite( float t, float p0, float p1, float p2 )
{
if ( fabs( p1 - p0 ) > 0.5f )
{
if ( p0 < p1 )
p0 += 1.0f;
else
p1 += 1.0f;
}
if ( fabs( p2 - p1 ) > 0.5f )
{
if ( p1 < p2 )
{
p1 += 1.0f;
// see if we need to fix up p0
// important for vars that are decreasing from p0->p1->p2 where
// p1 is fixed up relative to p2, eg p0 = 0.2, p1 = 0.1, p2 = 0.9
if ( abs( p1 - p0 ) > 0.5 )
{
if ( p0 < p1 )
p0 += 1.0f;
else
p1 += 1.0f;
}
}
else
{
p2 += 1.0f;
}
}
float s = Lerp_Hermite( t, p0, p1, p2 );
s = s - (int)(s);
if (s < 0.0f)
{
s = s + 1.0f;
}
return s;
}
// NOTE: C_AnimationLayer has its own versions of these functions in animationlayer.h.
#endif // LERP_FUNCTIONS_H