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<!DOCTYPE html>
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< meta charset = "utf-8" >
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< meta property = "og:image" itemprop = "image primaryImageOfPage" content = "https://hajimehoshi.github.io/ebiten/images/examples/rotate.png" >
< meta name = "description" content = "Ebiten example - rotate" >
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< link rel = "shortcut icon" href = "../favicon.png" type = "image/png" >
< link rel = "icon" href = "../favicon.png" type = "image/png" >
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< title > Ebiten example - rotate< / title >
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< link rel = "stylesheet" href = "../stylesheets/bootstrap.min.css" >
< link rel = "stylesheet" href = "../stylesheets/highlight-github.css" >
< link rel = "stylesheet" href = "../stylesheets/ebiten.css" >
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< script src = "../scripts/googleanalytics.js" > < / script >
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< nav class = "navbar" > < div class = "container" >
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< nav class = "d-flex flex-row" style = "width: 100%;" >
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< div class = "nav mr-auto" > < a class = "navbar-brand" href = "../" > < img src = "../images/logo_white.svg" alt = "EBITEN" > < / a > < / div >
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< ul class = "nav" >
< li class = "nav-item" > < a class = "nav-link" href = "https://github.com/hajimehoshi/ebiten" > GitHub< / a > < / li >
< li class = "nav-item" > < a class = "nav-link" href = "https://godoc.org/github.com/hajimehoshi/ebiten" > GoDoc< / a > < / li >
< li class = "nav-item" > < a class = "nav-link" href = "https://github.com/hajimehoshi/ebiten/wiki" > Wiki< / a >
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< li class = "nav-item" > < a class = "nav-link" href = "https://ebiten-playground.github.io/" > Playground< / a >
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< / ul >
< / nav >
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< / div > < / nav >
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< main > < div class = "container" >
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< h2 > Ebiten example - rotate< / h2 >
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< iframe src = "rotate.content.html" width = "640" height = "480" > < / iframe >
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< div class = "card" > < pre class = "card-body" > < code class = "language-go" > // + build example
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package main
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import (
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_ " image/jpeg"
" log"
" math"
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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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count = 0
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gophersImage *ebiten.Image
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)
func update(screen *ebiten.Image) error {
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count+ +
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if ebiten.IsRunningSlowly() {
return nil
}
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w, h := gophersImage.Size()
op := & ebiten.DrawImageOptions{}
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// Move the image' s center to the screen' s upper-left corner.
// This is a prepartion for rotating. When geometry matrices are applied,
// the origin point is the upper-left corner.
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op.GeoM.Translate(-float64(w)/2, -float64(h)/2)
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// Rotate the image. As a result, the anchor point of this rotate is
// the center of the image.
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op.GeoM.Rotate(float64(count%360) * 2 * math.Pi / 360)
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// Move the image to the screen' s center.
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op.GeoM.Translate(screenWidth/2, screenHeight/2)
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screen.DrawImage(gophersImage, op)
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return nil
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}
func main() {
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var err error
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gophersImage, _, err = ebitenutil.NewImageFromFile(" _resources/images/gophers.jpg" , ebiten.FilterDefault)
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if err != nil {
log.Fatal(err)
}
if err := ebiten.Run(update, screenWidth, screenHeight, 2, " Rotate (Ebiten Demo)" ); err != nil {
log.Fatal(err)
}
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}
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< / code > < / pre > < / div >
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< / div > < / main >
< footer > < div class = "container" >
< p > © 2013 Hajime Hoshi< / p >
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< p > Code is licensed under < a href = "https://github.com/hajimehoshi/ebiten/blob/master/LICENSE" > the Apache License 2.0< / a > .< / p >
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< 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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< script src = "../scripts/highlight.pack.js" > < / script >
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< script > hljs . initHighlightingOnLoad ( ) ; < / script >
