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