Done server

go.mod

@@ -0,0 +1,3 @@
+module gifServer
+
+go 1.18

lissajous.go

@@ -0,0 +1,38 @@
+package main
+
+import (
+	"image"
+	"image/color"
+	"image/gif"
+	"io"
+	"math"
+	"math/rand"
+	"time"
+)
+
+var palette = []color.Color{color.White, color.Black}
+
+const (
+	whiteIndex = 0
+	blackIndex = 1
+)
+
+func Lissajous(out io.Writer, cycles int, size int, nframes int, delay int, res float64) {
+	rand.Seed(time.Now().UTC().UnixNano())
+	freq := rand.Float64() * 3.0
+	anim := gif.GIF{LoopCount: nframes}
+	phase := 0.0
+	for i := 0; i < nframes; i++ {
+		rect := image.Rect(0, 0, 2*size+1, 2*size+1)
+		img := image.NewPaletted(rect, palette)
+		for t := 0.0; t < float64(cycles)*2*math.Pi; t += res {
+			x := math.Sin(t)
+			y := math.Sin(t*freq + phase)
+			img.SetColorIndex(size+int(x*float64(size)+0.5), size+int(y*float64(size)+0.5), blackIndex)
+		}
+		phase += 0.1
+		anim.Delay = append(anim.Delay, delay)
+		anim.Image = append(anim.Image, img)
+	}
+	gif.EncodeAll(out, &anim)
+}

server.go

@@ -0,0 +1,58 @@
+package main
+
+import (
+	"log"
+	"net/http"
+	"strconv"
+)
+
+var cycles, size, nframes, delay = 5, 100, 64, 8
+var res = 0.001
+
+func main() {
+	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		cycles, size, nframes, delay, res = parse(r)
+		Lissajous(w, cycles, size, nframes, delay, res)
+	})
+	log.Fatal(http.ListenAndServe("localhost:8000", nil))
+}
+
+func parse(r *http.Request) (int, int, int, int, float64) {
+	q := r.URL.Query()
+	if q.Has("cycles") {
+		var err error
+		cycles, err = strconv.Atoi(q["cycles"][0])
+		if err != nil {
+			panic(err)
+		}
+	}
+	if q.Has("size") {
+		var err error
+		size, err = strconv.Atoi(q["size"][0])
+		if err != nil {
+			panic(err)
+		}
+	}
+	if q.Has("nframes") {
+		var err error
+		nframes, err = strconv.Atoi(q["nframes"][0])
+		if err != nil {
+			panic(err)
+		}
+	}
+	if q.Has("delay") {
+		var err error
+		delay, err = strconv.Atoi(q["delay"][0])
+		if err != nil {
+			panic(err)
+		}
+	}
+	if q.Has("res") {
+		var err error
+		res, err = strconv.ParseFloat(q["res"][0], 64)
+		if err != nil {
+			panic(err)
+		}
+	}
+	return cycles, size, nframes, delay, res
+}