Curves.h

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//
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//      ██║██╔══██╗    ██║     ██║██╔══██╗██╔════╝      ** JPLSpatial **
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//   Copyright 2024 Jaroslav Pevno, JPLSpatial is offered under the terms of the ISC license:
//
//   Permission to use, copy, modify, and/or distribute this software for any purpose with or
//   without fee is hereby granted, provided that the above copyright notice and this permission
//   notice appear in all copies. THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
//   WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
//   AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
//   CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
//   WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
//   CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 
#pragma once
 
#include "JPLSpatial/Core.h"
 
#include <cmath>
#include <numbers>
#include <algorithm>
 
namespace JPL
{
    namespace Curve
    {
        struct Point
        {
            float X;
            float Y;
        };
 
        enum class EType
        {
            Constant,
            Linear,
            SineFadeIn,
            SineFadeOut,
            SCurve,
            //InvertedSCurve,
            LogarithmicBase1_41,
            LogarithmicBase3,
            ExponentialBase1_41,
            ExponentialBase3
        };
 
        namespace Internal
        {
            static constexpr float halfPi = std::numbers::pi_v<float> *0.5f;
            static const float log1_41 = std::log(1.41f);
            static const float log1_41_inv = 1.0f / log1_41;
            static const float log3 = std::log(3.0f);
            static const float log3_inv = 1.0f / log3;
        }
 
        JPL_INLINE float EvaluateConstant(float t)              { return 1.0f; }
        JPL_INLINE float EvaluateLinear(float t)                { return t; }
        JPL_INLINE float EvaluateSineFadeIn(float t)            { return std::sin(t * Internal::halfPi); }
        JPL_INLINE float EvaluateSineFadeOut(float t)           { return 1.0f - std::cos(t * Internal::halfPi); }
        JPL_INLINE float EvaluateSCurve(float t)                { return t * t * (3 - 2 * t); }
        JPL_INLINE float EvaluateLogarithmicBase1_41(float t)   { return std::log(1.0f + 0.41f * t) * Internal::log1_41_inv; }
        JPL_INLINE float EvaluateLogarithmicBase3(float t)      { return std::log(1.0f + 2.0f * t) * Internal::log3_inv; }
        JPL_INLINE float EvaluateExponentialBase1_41(float t)   { static constexpr float inv_0_41 = 1.0f / 0.41f; return (std::pow(1.41f, t) - 1.0f) * inv_0_41; }
        JPL_INLINE float EvaluateExponentialBase3(float t)      { return(std::pow(3.0f, t) - 1.0f) * 0.5f; }
 
        JPL_INLINE float EvaluateCurve(EType type, float t)
        {
            switch (type)
            {
            case EType::Constant:               return EvaluateConstant(t);
            case EType::Linear:                 return EvaluateLinear(t);
            case EType::SineFadeIn:             return EvaluateSineFadeIn(t);
            case EType::SineFadeOut:            return EvaluateSineFadeOut(t);
            case EType::SCurve:                 return EvaluateSCurve(t);
            case EType::LogarithmicBase1_41:    return EvaluateLogarithmicBase1_41(t);
            case EType::LogarithmicBase3:       return EvaluateLogarithmicBase3(t);
            case EType::ExponentialBase1_41:    return EvaluateExponentialBase1_41(t);
            case EType::ExponentialBase3:       return EvaluateExponentialBase3(t);
            default:
                return t;
            }
        }
    } // namespace Curve
} // namespace JPL