/
main.go
70 lines (56 loc) · 1.42 KB
/
main.go
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package main
import (
"image"
"image/color"
"image/gif"
"io"
"log"
"math"
"math/rand"
"net/http"
"strconv"
)
var palette = []color.Color{color.White, color.Black}
const (
whiteIndex = 0
blackIndex = 1
)
func main() {
http.HandleFunc("/", handler)
log.Fatal(http.ListenAndServe("localhost:8000", nil))
}
func handler(w http.ResponseWriter, r *http.Request) {
cycles := 5 // default number
res := 0.001 // default
size := 100 // default
nframes := 64 // default
delay := 8 // default
for param, values := range r.Form {
value := values[0]
switch param {
case "cycles":
if i, err := strconv.Atoi(value); err == nil {
cycles = i
}
}
}
lissajous(w, cycles, res, size, nframes, delay)
}
func lissajous(out io.Writer, cycles int, res float64, size int, nframes int, delay int) {
freq := rand.Float64() * 3.0 // relative frequency of y oscillator
anim := gif.GIF{LoopCount: nframes}
phase := 0.0 // phase difference
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(2*cycles)*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) // encoding errors ignore
}