fixed dependencies

vendor/gonum.org/v1/plot/tools/bezier/bezier.go

@@ -0,0 +1,80 @@
+// Copyright ©2013 The Gonum 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 bezier implements 2D Bézier curve calculation.
+package bezier // import "gonum.org/v1/plot/tools/bezier"
+
+import "gonum.org/v1/plot/vg"
+
+type point struct {
+	Point, Control vg.Point
+}
+
+// Curve implements Bezier curve calculation according to the algorithm of Robert D. Miller.
+//
+// Graphics Gems 5, 'Quick and Simple Bézier Curve Drawing', pages 206-209.
+type Curve []point
+
+// NewCurve returns a Curve initialized with the control points in cp.
+func New(cp ...vg.Point) Curve {
+	if len(cp) == 0 {
+		return nil
+	}
+	c := make(Curve, len(cp))
+	for i, p := range cp {
+		c[i].Point = p
+	}
+
+	var w vg.Length
+	for i, p := range c {
+		switch i {
+		case 0:
+			w = 1
+		case 1:
+			w = vg.Length(len(c)) - 1
+		default:
+			w *= vg.Length(len(c)-i) / vg.Length(i)
+		}
+		c[i].Control.X = p.Point.X * w
+		c[i].Control.Y = p.Point.Y * w
+	}
+
+	return c
+}
+
+// Point returns the point at t along the curve, where 0 ≤ t ≤ 1.
+func (c Curve) Point(t float64) vg.Point {
+	c[0].Point = c[0].Control
+	u := t
+	for i, p := range c[1:] {
+		c[i+1].Point = vg.Point{
+			X: p.Control.X * vg.Length(u),
+			Y: p.Control.Y * vg.Length(u),
+		}
+		u *= t
+	}
+
+	var (
+		t1 = 1 - t
+		tt = t1
+	)
+	p := c[len(c)-1].Point
+	for i := len(c) - 2; i >= 0; i-- {
+		p.X += c[i].Point.X * vg.Length(tt)
+		p.Y += c[i].Point.Y * vg.Length(tt)
+		tt *= t1
+	}
+
+	return p
+}
+
+// Curve returns a slice of vg.Point, p, filled with points along the Bézier curve described by c.
+// If the length of p is less than 2, the curve points are undefined. The length of p is not
+// altered by the call.
+func (c Curve) Curve(p []vg.Point) []vg.Point {
+	for i, nf := 0, float64(len(p)-1); i < len(p); i++ {
+		p[i] = c.Point(float64(i) / nf)
+	}
+	return p
+}