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/*
* FadeLaws.h
* ----------
* Purpose: Various fade law implementations for sample and pattern fading / interpolation
* Notes : (currently none)
* Authors: OpenMPT Devs
* The OpenMPT source code is released under the BSD license. Read LICENSE for more details.
*/
#pragma once
#include "openmpt/all/BuildSettings.hpp"
#include "mpt/base/numbers.hpp"
#include <cmath>
OPENMPT_NAMESPACE_BEGIN
namespace Fade
{
enum Law
{
kLinear,
kPow,
kSqrt,
kLog,
kQuarterSine,
kHalfSine,
};
// Maps fade curve position in [0,1] to value in [0,1]
typedef double (*Func) (double pos);
inline double LinearFunc(double pos)
{ return pos; }
inline double PowFunc(double pos)
{ return pos * pos; }
inline double SqrtFunc(double pos)
{ return std::sqrt(pos); }
inline double LogFunc(double pos)
{ return std::log10(1.0 + pos * 99.0) * 0.5; }
inline double QuarterSineFunc(double pos)
{ return std::sin((0.5 * mpt::numbers::pi) * pos); }
inline double HalfSineFunc(double pos)
{ return (1.0 + std::cos(mpt::numbers::pi + mpt::numbers::pi * pos)) * 0.5; }
inline Func GetFadeFunc(Law fadeLaw)
{
switch(fadeLaw)
{
default:
case Fade::kLinear: return LinearFunc;
case Fade::kPow: return PowFunc;
case Fade::kSqrt: return SqrtFunc;
case Fade::kLog: return LogFunc;
case Fade::kQuarterSine: return QuarterSineFunc;
case Fade::kHalfSine: return HalfSineFunc;
}
}
}
OPENMPT_NAMESPACE_END
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