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<!DOCTYPE html>
< link rel = "shortcut icon" href = "../favicon.png" type = "image/png" >
< link rel = "icon" href = "../favicon.png" type = "image/png" >
< title > Ebiten example - sprites< / title >
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< link rel = "stylesheet" href = "/stylesheets/bootstrap.min.css" >
< link rel = "stylesheet" href = "/stylesheets/ebiten.css" >
< header class = "navbar" > < div class = "container" >
< div class = "navbar-header" >
< a class = "navbar-brand" href = "/" > Ebiten< / a >
< / div >
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< nav class = "collapse navbar-collapse" >
< ul class = "nav navbar-nav navbar-right" >
< li > < a href = "https://github.com/hajimehoshi/ebiten" > GitHub< / a > < / li >
< li > < a href = "http://godoc.org/github.com/hajimehoshi/ebiten" > GoDoc< / a > < / li >
< li > < a href = "https://github.com/hajimehoshi/ebiten/wiki" > Wiki< / a >
< / ul >
< / nav >
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< / header >
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< main > < div class = "container" >
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< h2 > Ebiten example - sprites< / h2 >
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< iframe src = "sprites.content.html" width = "640" height = "480" > < / iframe >
< pre > < code > // + build example
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package main
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import (
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" fmt"
_ " image/png"
" log"
" math/rand"
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" github.com/hajimehoshi/ebiten"
" github.com/hajimehoshi/ebiten/ebitenutil"
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)
const (
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screenWidth = 320
screenHeight = 240
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)
var (
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ebitenImage *ebiten.Image
ebitenImageWidth = 0
ebitenImageHeight = 0
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)
type Sprite struct {
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image *ebiten.Image
x int
y int
vx int
vy int
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}
func (s *Sprite) Update() {
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s.x + = s.vx
s.y + = s.vy
if s.x < 0 {
s.x = -s.x
s.vx = -s.vx
}
if s.y < 0 {
s.y = -s.y
s.vy = -s.vy
}
w, h := s.image.Size()
if screenWidth < = s.x+ w {
s.x = 2*(screenWidth-w) - s.x
s.vx = -s.vx
}
if screenHeight < = s.y+ h {
s.y = 2*(screenHeight-h) - s.y
s.vy = -s.vy
}
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}
type Sprites struct {
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sprites []*Sprite
num int
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}
func (s Sprites) Update() {
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for _, sprite := range s.sprites {
sprite.Update()
}
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}
func (s Sprites) Len() int {
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return s.num
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}
func (s Sprites) Dst(i int) (x0, y0, x1, y1 int) {
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if s.num < = i {
return 0, 0, 0, 0
}
ss := s.sprites[i]
return ss.x, ss.y, ss.x + ebitenImageWidth, ss.y + ebitenImageHeight
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}
func (s Sprites) Src(i int) (x0, y0, x1, y1 int) {
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if s.num < = i {
return 0, 0, 0, 0
}
return 0, 0, ebitenImageWidth, ebitenImageHeight
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}
const (
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MinSprites = 0
MaxSprites = 50000
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)
var sprites = & Sprites{make([]*Sprite, MaxSprites), 500}
func update(screen *ebiten.Image) error {
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if ebiten.IsKeyPressed(ebiten.KeyLeft) {
sprites.num -= 20
if sprites.num < MinSprites {
sprites.num = MinSprites
}
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}
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if ebiten.IsKeyPressed(ebiten.KeyRight) {
sprites.num + = 20
if MaxSprites < sprites.num {
sprites.num = MaxSprites
}
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}
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sprites.Update()
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if ebiten.IsRunningSlowly() {
return nil
}
op := & ebiten.DrawImageOptions{
ImageParts: sprites,
}
op.ColorM.Scale(1.0, 1.0, 1.0, 0.5)
if err := screen.DrawImage(ebitenImage, op); err != nil {
return err
}
msg := fmt.Sprintf(`FPS: %0.2f
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Num of sprites: %d
Press < - or -> to change the number of sprites`, ebiten.CurrentFPS(), sprites.Len())
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if err := ebitenutil.DebugPrint(screen, msg); err != nil {
return err
}
return nil
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}
func main() {
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var err error
ebitenImage, _, err = ebitenutil.NewImageFromFile(" _resources/images/ebiten.png" , ebiten.FilterNearest)
if err != nil {
log.Fatal(err)
}
ebitenImageWidth, ebitenImageHeight = ebitenImage.Size()
for i := range sprites.sprites {
w, h := ebitenImage.Size()
x, y := rand.Intn(screenWidth-w), rand.Intn(screenHeight-h)
vx, vy := 2*rand.Intn(2)-1, 2*rand.Intn(2)-1
sprites.sprites[i] = & Sprite{
image: ebitenImage,
x: x,
y: y,
vx: vx,
vy: vy,
}
}
if err := ebiten.Run(update, screenWidth, screenHeight, 2, " Sprites (Ebiten Demo)" ); err != nil {
log.Fatal(err)
}
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}
< / code > < / pre >
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< / div > < / main >
< footer > < div class = "container" >
< p > © 2013 Hajime Hoshi< / p >
< p > Code is licensed under < a href = "https://github.com/hajimehoshi/ebiten/blob/master/LICENSE" > Apache License 2.0< / a > .< / p >
< p > The content of this page is licensed under < a href = "https://creativecommons.org/licenses/by/4.0/" > the Creative Commons Attribution 4.0 License< / a > .< / p >
< / div > < / footer >
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