Archimedean spiral in golang using web server and png renderer

main.go

package main

import (
	"image"
	"image/color"
	"image/png"
	"io"
	"math"
	"net/http"
)

var palette = []color.Color{color.White, color.Black}

const (
	White = 0
	Black = 1
)

func draw(out io.Writer) {
	w, h := 640, 640
	rect := image.Rect(0, 0, w, h)
	img := image.NewPaletted(rect, palette)
	a := 1.5
	b := -2.4
	for t := 0; t < 360*20; t++ {
		trad := float64(t) * math.Pi / 180.0
		x := (a + b*trad) * math.Cos(trad)
		y := (a + b*trad) * math.Sin(trad)
		img.SetColorIndex(w/2+int(x), h/2+int(y), Black)
	}
	png.Encode(out, img)
}

func main() {
	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		draw(w)
	})
	http.ListenAndServe(":8080", nil)
}