66 lines
1.5 KiB
Go
66 lines
1.5 KiB
Go
package main
|
|
|
|
import (
|
|
"image"
|
|
"image/color"
|
|
"image/gif"
|
|
"io"
|
|
"math"
|
|
"math/rand"
|
|
"os"
|
|
)
|
|
|
|
import (
|
|
"log"
|
|
"net/http"
|
|
"time"
|
|
)
|
|
|
|
var palette = []color.Color{
|
|
color.Black,
|
|
color.RGBA{0xff, 0x00, 0x00, 0xff},
|
|
color.RGBA{0x00, 0xff, 0x00, 0xff},
|
|
color.RGBA{0x00, 0x00, 0xff, 0xff},
|
|
}
|
|
|
|
func main() {
|
|
rand.Seed(time.Now().UTC().UnixNano())
|
|
|
|
if len(os.Args) > 1 && os.Args[1] == "web" {
|
|
handler := func(w http.ResponseWriter, r *http.Request) {
|
|
lissajous(w)
|
|
}
|
|
http.HandleFunc("/", handler)
|
|
log.Fatal(http.ListenAndServe("localhost:8000", nil))
|
|
return
|
|
}
|
|
lissajous(os.Stdout)
|
|
}
|
|
|
|
func lissajous(out io.Writer) {
|
|
const (
|
|
cycles = 5 // number of complete x oscillator revolutions
|
|
res = 0.001 // angular resolution
|
|
size = 100 // image canvas covers [-size..+size]
|
|
nframes = 64 // number of animation frames
|
|
delay = 8 // delay between frames in 10ms units
|
|
)
|
|
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 < cycles*2*math.Pi; t += res {
|
|
x := math.Sin(t)
|
|
y := math.Sin(t*freq + phase)
|
|
img.SetColorIndex(size+int(x*size+0.5), size+int(y*size+0.5),
|
|
uint8(rand.Intn(3)))
|
|
}
|
|
phase += 0.1
|
|
anim.Delay = append(anim.Delay, delay)
|
|
anim.Image = append(anim.Image, img)
|
|
}
|
|
gif.EncodeAll(out, &anim) // NOTE: ignoring encoding errors
|
|
}
|