mandiserver.go

package main

import (
	"image"
	"image/color"
	"image/png"
	"math/cmplx"
	"log"
	"net/http"
)

func main() {
	http.HandleFunc("/", handler)
	log.Fatal(http.ListenAndServe("localhost:8000", nil))	
}

func handler(w http.ResponseWriter, r *http.Request) {

	const (
		xmin, ymin, xmax, ymax = -2, -2, +2, +2
		width, height = 1024, 1024
	)

	img := image.NewRGBA(image.Rect(0, 0, width, height))
	for py := 0; py < height; py++ {
		y := float64(py) / height * (ymax - ymin) + ymin
		for px := 0; px < width; px++ {
			x := float64(px) / width * (xmax - xmin) + xmin
			z := complex(x, y)
			img.Set(px, py, mandlebrot(z))
		}
	}

	png.Encode(w, img)
}

func mandlebrot(z complex128) color.Color {
	const iterations = 200
	const contrast = 15

	var v complex128
	for n := uint8(0); n < iterations; n++ {
		v = v * v + z
		if cmplx.Abs(v) > 2 {
			return color.Gray{255 - contrast * n}
		}
		
	}

	return color.Black
}