LinearFunction.hh

// Copyright QED Software 2023.
 
#ifndef GRAIL_LINEAR_FUNCTION_H
#define GRAIL_LINEAR_FUNCTION_H
 
#include "Curve.hh"
 
namespace grail
{
namespace evaluator
{
    template <typename ContextType>
    class LinearFunction final : public Curve<ContextType>
    {
    public:
        LinearFunction(std::shared_ptr<Evaluator<ContextType>> childEvaluator,
                       float slope,
                       float intercept)
            : Curve<ContextType>{childEvaluator}, slope{slope}, intercept{intercept}
        {
        }
 
        LinearFunction(std::shared_ptr<Evaluator<ContextType>> childEvaluator,
                       std::pair<float, float> firstPoint,
                       std::pair<float, float> secondPoint)
            : Curve<ContextType>{childEvaluator}
        {
            assert(firstPoint.first != secondPoint.first);
            if(firstPoint.second == secondPoint.second)
            {
                slope = 0.0f;
                intercept = firstPoint.second;
            }
            else
            {
                if(firstPoint.first > secondPoint.first)
                {
                    float x = firstPoint.first;
                    float y = firstPoint.second;
                    firstPoint.first = secondPoint.first;
                    firstPoint.second = secondPoint.second;
                    secondPoint.first = x;
                    secondPoint.second = y;
                }
                slope = (secondPoint.second - firstPoint.second) / (secondPoint.first - firstPoint.first);
                intercept = firstPoint.second - (slope * firstPoint.first);
            }
        }
 
        virtual float Sample(float argument) const override final
        {
            return slope * argument + intercept;
        }
 
        float GetSlope() const { return slope; }
        float GetIntercept() const { return intercept; }
 
        virtual data::EvaluatorType GetEvaluatorType() const override final { return data::EvaluatorType::CURVE_LINEAR; }
 
    private:
        float slope = 0.0f;
        float intercept = 0.0f;
    };
}
}
 
#endif // GRAIL_LINEAR_FUNCTION_H