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// Copyright ©2019 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 plotter_test
/*
import (
"image/color"
"image/png"
"log"
"math"
"os"
"gonum.org/v1/plot"
"gonum.org/v1/plot/palette/moreland"
"gonum.org/v1/plot/plotter"
"gonum.org/v1/plot/vg"
"gonum.org/v1/plot/vg/draw"
"gonum.org/v1/plot/vg/vgimg"
)
func ExampleField() {
f := plotter.NewField(field{
r: 17, c: 19,
fn: func(x, y float64) plotter.XY {
return plotter.XY{
X: y,
Y: -x,
}
},
})
f.LineStyle.Width = 0.2
p, err := plot.New()
if err != nil {
log.Panic(err)
}
p.Title.Text = "Vector field"
p.X.Tick.Marker = integerTicks{}
p.Y.Tick.Marker = integerTicks{}
p.Add(f)
img := vgimg.New(250, 175)
dc := draw.New(img)
p.Draw(dc)
w, err := os.Create("testdata/field.png")
if err != nil {
log.Panic(err)
}
png := vgimg.PngCanvas{Canvas: img}
if _, err = png.WriteTo(w); err != nil {
log.Panic(err)
}
}
func ExampleField_colors() {
f := plotter.NewField(field{
r: 5, c: 9,
fn: func(x, y float64) plotter.XY {
return plotter.XY{
X: -0.75*x + y,
Y: -0.75*y - x,
}
},
})
pal := moreland.ExtendedBlackBody()
pal.SetMin(0)
pal.SetMax(1.1) // Use 1.1 to make highest magnitude vectors visible on white.
// Provide a DrawGlyph function to render a custom
// vector instead of the default monochrome arrow.
f.DrawGlyph = func(c vg.Canvas, sty draw.LineStyle, v plotter.XY) {
c.Push()
defer c.Pop()
mag := math.Hypot(v.X, v.Y)
var pa vg.Path
if mag == 0 {
// Draw a black dot for zero vectors.
c.SetColor(color.Black)
pa.Move(vg.Point{X: sty.Width})
pa.Arc(vg.Point{}, sty.Width, 0, 2*math.Pi)
pa.Close()
c.Fill(pa)
return
}
// Choose a color from the palette for the magnitude.
col, err := pal.At(mag)
if err != nil {
panic(err)
}
c.SetColor(col)
pa.Move(vg.Point{})
pa.Line(vg.Point{X: 1, Y: 0})
pa.Close()
c.Stroke(pa)
}
p, err := plot.New()
if err != nil {
log.Panic(err)
}
p.Title.Text = "Vortex"
p.X.Tick.Marker = integerTicks{}
p.Y.Tick.Marker = integerTicks{}
p.Add(f)
img := vgimg.New(250, 175)
dc := draw.New(img)
p.Draw(dc)
w, err := os.Create("testdata/color_field.png")
if err != nil {
log.Panic(err)
}
defer w.Close()
png := vgimg.PngCanvas{Canvas: img}
if _, err = png.WriteTo(w); err != nil {
log.Panic(err)
}
}
func ExampleField_gophers() {
file, err := os.Open("testdata/gopher_running.png")
if err != nil {
log.Panic(err)
}
defer file.Close()
gopher, err := png.Decode(file)
if err != nil {
log.Panic(err)
}
f := plotter.NewField(field{
r: 5, c: 9,
fn: func(x, y float64) plotter.XY {
return plotter.XY{
X: -0.75*x + y,
Y: -0.75*y - x,
}
},
})
// Provide a DrawGlyph function to render a custom
// vector glyph instead of the default arrow.
f.DrawGlyph = func(c vg.Canvas, _ draw.LineStyle, v plotter.XY) {
// The canvas is unscaled if the vector has a zero
// magnitude, so return in that case.
if math.Hypot(v.X, v.Y) == 0 {
return
}
// Vector glyphs are scaled to half unit length by the
// plotter, so scale the gopher to twice unit size so
// it fits the cell, and center on the cell.
c.Translate(vg.Point{X: -1, Y: -1})
c.DrawImage(vg.Rectangle{Max: vg.Point{X: 2, Y: 2}}, gopher)
}
p, err := plot.New()
if err != nil {
log.Panic(err)
}
p.Title.Text = "Gopher vortex"
p.X.Tick.Marker = integerTicks{}
p.Y.Tick.Marker = integerTicks{}
p.Add(f)
img := vgimg.New(250, 175)
dc := draw.New(img)
p.Draw(dc)
w, err := os.Create("testdata/gopher_field.png")
if err != nil {
log.Panic(err)
}
png := vgimg.PngCanvas{Canvas: img}
if _, err = png.WriteTo(w); err != nil {
log.Panic(err)
}
}
*/
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