CurveEvaluation.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Curves/RichCurve.h"
 
namespace UE
{
    namespace Curves
    {
        /* Solve Cubic Euqation using Cardano's forumla
        * Adopted from Graphic Gems 1
        * https://github.com/erich666/GraphicsGems/blob/master/gems/Roots3And4.c
        *  Solve cubic of form
        *
        * @param Coeff Coefficient parameters of form  Coeff[0] + Coeff[1]*x + Coeff[2]*x^2 + Coeff[3]*x^3 + Coeff[4]*x^4 = 0
        * @param Solution Up to 3 real solutions. We don't include imaginary solutions, would need a complex number objecct
        * @return Returns the number of real solutions returned in the Solution array.
        */
        ENGINE_API int32 SolveCubic(double Coeff[4], double Solution[3]);
 
        template<typename CurveValueType>
        CurveValueType BezierInterp(CurveValueType P0, CurveValueType P1, CurveValueType P2, CurveValueType P3, float Alpha)
        {
            const CurveValueType P01 = FMath::Lerp(P0, P1, Alpha);
            const CurveValueType P12 = FMath::Lerp(P1, P2, Alpha);
            const CurveValueType P23 = FMath::Lerp(P2, P3, Alpha);
            const CurveValueType P012 = FMath::Lerp(P01, P12, Alpha);
            const CurveValueType P123 = FMath::Lerp(P12, P23, Alpha);
            const CurveValueType P0123 = FMath::Lerp(P012, P123, Alpha);
 
            return P0123;
        }
 
        /*
        *   Convert the control values for a polynomial defined in the Bezier
        *       basis to a polynomial defined in the power basis (t^3 t^2 t 1).
        */
        ENGINE_API void BezierToPower(double A1, double B1, double C1, double D1, double* A2, double* B2, double* C2, double* D2);
        
        float WeightedEvalForTwoKeys(float Key1Value, float Key1Time, float Key1LeaveTangent, float Key1LeaveTangentWeight, ERichCurveTangentWeightMode Key1TangentWeightMode, float Key2Value, float Key2Time, float Key2ArriveTangent, float Key2ArriveTangentWeight,  ERichCurveTangentWeightMode Key2TangentWeightMode, float InTime);
 
        bool IsItNotWeighted(const FRichCurveKey& Key1, const FRichCurveKey& Key2);
 
        bool IsWeighted(const FRichCurveKey& Key1, const FRichCurveKey& Key2);
 
        ENGINE_API float EvalForTwoKeys(const FRichCurveKey& Key1, const FRichCurveKey& Key2, const float InTime);
    }
}