X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=piecewise_interpolator.h;fp=piecewise_interpolator.h;h=17a9d8b8c41f45c8b1080e0ab0068250f88f3960;hb=9e93fbea58c068d14dd9dad5d0f5226edeef3395;hp=0000000000000000000000000000000000000000;hpb=52c3ac9a9a358ea422810b9376651de9f283bd12;p=nageru

diff --git a/piecewise_interpolator.h b/piecewise_interpolator.h
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+++ b/piecewise_interpolator.h
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+#ifndef _PIECEWISE_INTERPOLATOR_H
+#define _PIECEWISE_INTERPOLATOR_H
+
+// A class to do piecewise linear interpolation of one scale to another
+// (and back). Typically used to implement nonlinear dB mappings for sliders
+// or meters, thus the nomenclature.
+
+#include <vector>
+
+class PiecewiseInterpolator {
+public:
+	// Both dB and fraction values must go from high to low.
+	struct ControlPoint {
+		double db_value;
+		double fraction;
+	};
+	PiecewiseInterpolator(const std::vector<ControlPoint> &control_points)
+		: control_points(control_points) {}
+
+	double fraction_to_db(double db) const;
+	double db_to_fraction(double x) const;
+
+private:
+	const std::vector<ControlPoint> control_points;
+};
+
+#endif  // !defined(_PIECEWISE_INTERPOLATOR_H)