golang pixel lib clock

pixclock.go

package main

import (
	"math"
	"time"

	"github.com/faiface/pixel"
	"github.com/faiface/pixel/imdraw"
	"github.com/faiface/pixel/pixelgl"
	"golang.org/x/image/colornames"
)

const (
	m = (math.Pi / 180.0) * 6.0
)

func drawClock(win *pixelgl.Window) {
	t := time.Now().Local()
	w := win.Bounds().W()
	h := win.Bounds().H()
	cX := win.Bounds().Center().X
	cY := win.Bounds().Center().Y
	l := (math.Min(w, h) / 2) - 10
	i := imdraw.New(nil)

	// dial
	i.Color = colornames.Darkgray
	i.Push(pixel.V(cX, cY))
	i.Circle(l, 5)

	// seconds
	r := (float64(t.Second()) - 15.0) * m
	x := math.Cos(r)*(8*l/9) + cX
	y := h - (math.Sin(r)*(8*l/9) + cY)
	i.Color = colornames.Red
	i.Push(pixel.V(cX, cY), pixel.V(x, y))
	i.Line(2)

	// minutes
	r = (float64(t.Minute()) - 15.0) * m
	x = math.Cos(r)*(4*l/5) + cX
	y = h - (math.Sin(r)*(4*l/5) + cY)
	i.Color = colornames.Navy
	i.Push(pixel.V(cX, cY), pixel.V(x, y))
	i.Line(5)

	// hours
	r = (float64((t.Hour()*5)+t.Minute()/10) - 15.0) * m
	x = math.Cos(r)*(2*l/3) + cX
	y = h - (math.Sin(r)*(2*l/3) + cY)
	i.Color = colornames.Darkgreen
	i.Push(pixel.V(cX, cY), pixel.V(x, y))
	i.Line(10)

	i.Draw(win)
}

func run() {
	cfg := pixelgl.WindowConfig{
		Title:     "Go Pixel Clock",
		Bounds:    pixel.R(0, 0, 1024, 768),
		Resizable: true,
	}
	win, err := pixelgl.NewWindow(cfg)
	if err != nil {
		panic(err)
	}

	t := time.Tick(time.Second / 4)

	for !win.Closed() {
		win.Clear(colornames.White)
		drawClock(win)
		win.Update()
		<-t
	}
}

func main() {
	pixelgl.Run(run)
}