ebiten 是golang的跨平台2D游戏引擎。以下是它自带的示例,运行程序后,会在屏幕上显示一个来回走动的golang宠物。
代码中有一点特殊的是,它居然用了两个init,不过看起来它只是顺序运行了而已,并没有什么问题。
不一定真的用它做游戏,可以把它的原理作为软件的启动界面是比较酷的。
//go:build example
// +build example
package main
import (
"bytes"
"image"
_ "image/png"
"log"
"math/rand"
"time"
"github.com/hajimehoshi/ebiten/v2"
rmascot "github.com/hajimehoshi/ebiten/v2/examples/resources/images/mascot"
)
const (
width = 200
height = 200
)
var (
gopher1 *ebiten.Image
gopher2 *ebiten.Image
gopher3 *ebiten.Image
)
func init() {
// Decode an image from the image file's byte slice.
// Now the byte slice is generated with //go:generate for Go 1.15 or older.
// If you use Go 1.16 or newer, it is strongly recommended to use //go:embed to embed the image file.
// See https://pkg.go.dev/embed for more details.
img1, _, err := image.Decode(bytes.NewReader(rmascot.Out01_png))
if err != nil {
log.Fatal(err)
}
gopher1 = ebiten.NewImageFromImage(img1)
img2, _, err := image.Decode(bytes.NewReader(rmascot.Out02_png))
if err != nil {
log.Fatal(err)
}
gopher2 = ebiten.NewImageFromImage(img2)
img3, _, err := image.Decode(bytes.NewReader(rmascot.Out03_png))
if err != nil {
log.Fatal(err)
}
gopher3 = ebiten.NewImageFromImage(img3)
}
func init() {
rand.Seed(time.Now().UnixNano())
}
type mascot struct {
x16 int
y16 int
vx16 int
vy16 int
count int
}
func (m *mascot) Layout(outsideWidth, outsideHeight int) (int, int) {
return width, height
}
func (m *mascot) Update() error {
m.count++
sw, sh := ebiten.ScreenSizeInFullscreen()
ebiten.SetWindowPosition(m.x16/16, m.y16/16+sh-height)
if m.vx16 == 0 {
m.vx16 = 64
}
m.x16 += m.vx16
if m.x16/16 > sw-width && m.vx16 > 0 {
m.vx16 = -64
}
if m.x16 <= 0 && m.vx16 < 0 {
m.vx16 = 64
}
// Accelarate the mascot in the Y direction.
m.vy16 += 8
m.y16 += m.vy16
// If the mascot is on the ground, stop it in the Y direction.
if m.y16 >= 0 {
m.y16 = 0
m.vy16 = 0
}
// If the mascto is on the ground, cause an action in random.
if rand.Intn(60) == 0 && m.y16 == 0 {
switch rand.Intn(2) {
case 0:
// Jump.
m.vy16 = -240
case 1:
// Turn.
m.vx16 = -m.vx16
}
}
return nil
}
func (m *mascot) Draw(screen *ebiten.Image) {
img := gopher1
if m.y16 == 0 {
switch (m.count / 3) % 4 {
case 0:
img = gopher1
case 1, 3:
img = gopher2
case 2:
img = gopher3
}
}
op := &ebiten.DrawImageOptions{}
if m.vx16 < 0 {
op.GeoM.Scale(-1, 1)
op.GeoM.Translate(width, 0)
}
screen.DrawImage(img, op)
}
func main() {
ebiten.SetScreenTransparent(true)
ebiten.SetWindowDecorated(false)
ebiten.SetWindowFloating(true)
ebiten.SetWindowSize(width, height)
if err := ebiten.RunGame(&mascot{}); err != nil {
log.Fatal(err)
}
}