From 1a57267a17c2fc17fb6e104846fabc3e363c326c Mon Sep 17 00:00:00 2001 From: Emile Date: Fri, 16 Aug 2024 19:50:26 +0200 Subject: initial commit --- vendor/modernc.org/mathutil/envelope.go | 46 +++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) create mode 100644 vendor/modernc.org/mathutil/envelope.go (limited to 'vendor/modernc.org/mathutil/envelope.go') diff --git a/vendor/modernc.org/mathutil/envelope.go b/vendor/modernc.org/mathutil/envelope.go new file mode 100644 index 0000000..71980db --- /dev/null +++ b/vendor/modernc.org/mathutil/envelope.go @@ -0,0 +1,46 @@ +// Copyright (c) 2014 The mathutil Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package mathutil // import "modernc.org/mathutil" + +import ( + "math" +) + +// Approximation type determines approximation methods used by e.g. Envelope. +type Approximation int + +// Specific approximation method tags +const ( + _ Approximation = iota + Linear // As named + Sinusoidal // Smooth for all derivations +) + +// Envelope is an utility for defining simple curves using a small (usually) +// set of data points. Envelope returns a value defined by x, points and +// approximation. The value of x must be in [0,1) otherwise the result is +// undefined or the function may panic. Points are interpreted as dividing the +// [0,1) interval in len(points)-1 sections, so len(points) must be > 1 or the +// function may panic. According to the left and right points closing/adjacent +// to the section the resulting value is interpolated using the chosen +// approximation method. Unsupported values of approximation are silently +// interpreted as 'Linear'. +func Envelope(x float64, points []float64, approximation Approximation) float64 { + step := 1 / float64(len(points)-1) + fslot := math.Floor(x / step) + mod := x - fslot*step + slot := int(fslot) + l, r := points[slot], points[slot+1] + rmod := mod / step + switch approximation { + case Sinusoidal: + k := (math.Sin(math.Pi*(rmod-0.5)) + 1) / 2 + return l + (r-l)*k + case Linear: + fallthrough + default: + return l + (r-l)*rmod + } +} -- cgit 1.4.1