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// Copyright ©2016 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"
"log"
"math"
"gonum.org/v1/plot"
"gonum.org/v1/plot/palette/moreland"
"gonum.org/v1/plot/plotter"
"gonum.org/v1/plot/vg"
)
// ExamplePolygon_holes draws a polygon with holes, showing how
// the different built-in vg backends render polygons with holes.
// The output of this example is at
// https://github.com/gonum/plot/blob/master/plotter/testdata/polygon_holes_golden.png,
// https://github.com/gonum/plot/blob/master/plotter/testdata/polygon_holes_golden.svg,
// https://github.com/gonum/plot/blob/master/plotter/testdata/polygon_holes_golden.pdf, and
// https://github.com/gonum/plot/blob/master/plotter/testdata/polygon_holes_golden.eps.
func ExamplePolygon_holes() {
// Create an outer ring.
outer1 := plotter.XYs{{X: 0, Y: 0}, {X: 4, Y: 0}, {X: 4, Y: 4}, {X: 0, Y: 4}}
// Create an inner ring with the same
// winding order as the outer ring.
inner1 := plotter.XYs{{X: 0.5, Y: 0.5}, {X: 1.5, Y: 0.5}, {X: 1.5, Y: 1.5}, {X: 0.5, Y: 1.5}}
// Create an inner polygon with the opposite
// winding order as the outer polygon.
inner2 := plotter.XYs{{X: 3.5, Y: 2.5}, {X: 2.5, Y: 2.5}, {X: 2.5, Y: 3.5}, {X: 3.5, Y: 3.5}}
poly, err := plotter.NewPolygon(outer1, inner1, inner2)
if err != nil {
log.Panic(err)
}
poly.Color = color.NRGBA{B: 255, A: 255}
p, err := plot.New()
if err != nil {
log.Panic(err)
}
p.Title.Text = "Polygon with holes"
p.X.Label.Text = "X"
p.Y.Label.Text = "Y"
p.Add(poly)
p.Legend.Add("key", poly)
p.Legend.Font.Size = vg.Points(8)
p.Legend.TextStyle.Color = color.White
p.Legend.ThumbnailWidth = vg.Points(10)
// Here we save the image in different file formats
// to show how each back end handles polygon holes.
// The vgimg backend treats both internal polygons
// as holes by default.
err = p.Save(100, 100, "testdata/polygon_holes.png")
if err != nil {
log.Panic(err)
}
// The vgsvg, vgpdf, and vgeps backgrounds all treat
// the internal polygon with the opposite winding
// direction as a hole but do not consider the internal
// polygon with the same winding direction to be a hole.
err = p.Save(100, 100, "testdata/polygon_holes.svg")
if err != nil {
log.Panic(err)
}
err = p.Save(100, 100, "testdata/polygon_holes.pdf")
if err != nil {
log.Panic(err)
}
err = p.Save(100, 100, "testdata/polygon_holes.eps")
if err != nil {
log.Panic(err)
}
}
// ExamplePolygon_hexagons creates a heat map with hexagon shapes.
// The output of this example is at
// https://github.com/gonum/plot/blob/master/plotter/testdata/polygon_hexagons_golden.png.
func ExamplePolygon_hexagons() {
// hex returns a hexagon centered at (x,y) with radius r.
hex := func(x, y, r float64) plotter.XYs {
g := make(plotter.XYs, 6)
for i := range g {
g[i].X = x + r*math.Cos(math.Pi/3*float64(i))
g[i].Y = y + r*math.Sin(math.Pi/3*float64(i))
}
return g
}
p, err := plot.New()
if err != nil {
log.Panic(err)
}
p.Title.Text = "Hexagons"
p.X.Label.Text = "X"
p.Y.Label.Text = "Y"
colorMap := moreland.SmoothBlueRed()
colorMap.SetMax(2)
colorMap.SetMin(-2)
colorMap.SetConvergePoint(0)
const (
r = math.Pi / 4 // r is the hexagon radius.
// x0 and y0 are the beginning coordinates for the hexagon plot.
x0 = 0.0
y0 = 0.0
// nx and ny are the number of hexagons in the x and y directions.
nx = 5
ny = 5
)
// dx and dy are the distance between hexgons.
dx := 3 * r
dy := r * math.Sqrt(3)
xstart := []float64{x0, x0 - 1.5*r}
ystart := []float64{y0, y0 - r}
for i, xmin := range xstart {
ymin := ystart[i]
x := xmin
for ix := 0; ix < nx; ix++ {
y := ymin
for iy := 0; iy < ny; iy++ {
var poly *plotter.Polygon
poly, err = plotter.NewPolygon(hex(x, y, r))
if err != nil {
log.Panic(err)
}
poly.Color, err = colorMap.At(math.Sin(x) + math.Sin(y))
if err != nil {
log.Panic(err)
}
poly.LineStyle.Width = 0
p.Add(poly)
y += dy
}
x += dx
}
}
if err = p.Save(100, 100, "testdata/polygon_hexagons.png"); err != nil {
log.Panic(err)
}
}
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