ebiten/docs/examples/sprites.html

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  <h2>Ebiten example - sprites</h2>
  <iframe src="sprites.content.html" width="640" height="480"></iframe>
  <pre><code class="language-go">// &#43;build example

package main

import (
        &#34;fmt&#34;
        _ &#34;image/png&#34;
        &#34;log&#34;
        &#34;math&#34;
        &#34;math/rand&#34;

        &#34;github.com/hajimehoshi/ebiten&#34;
        &#34;github.com/hajimehoshi/ebiten/ebitenutil&#34;
)

const (
        screenWidth  = 320
        screenHeight = 240
        maxAngle     = 256
)

var (
        ebitenImage *ebiten.Image
)

type Sprite struct {
        imageWidth  int
        imageHeight int
        x           int
        y           int
        vx          int
        vy          int
        angle       int
}

func (s *Sprite) Update() {
        s.x &#43;= s.vx
        s.y &#43;= s.vy
        if s.x &lt; 0 {
                s.x = -s.x
                s.vx = -s.vx
        } else if screenWidth &lt;= s.x&#43;s.imageWidth {
                s.x = 2*(screenWidth-s.imageWidth) - s.x
                s.vx = -s.vx
        }
        if s.y &lt; 0 {
                s.y = -s.y
                s.vy = -s.vy
        } else if screenHeight &lt;= s.y&#43;s.imageHeight {
                s.y = 2*(screenHeight-s.imageHeight) - s.y
                s.vy = -s.vy
        }
        s.angle&#43;&#43;
        s.angle %= maxAngle
}

type Sprites struct {
        sprites []*Sprite
        num     int
}

func (s *Sprites) Update() {
        for _, sprite := range s.sprites {
                sprite.Update()
        }
}

const (
        MinSprites = 0
        MaxSprites = 50000
)

var (
        sprites = &amp;Sprites{make([]*Sprite, MaxSprites), 500}
        op      = &amp;ebiten.DrawImageOptions{}
)

func update(screen *ebiten.Image) error {
        if ebiten.IsKeyPressed(ebiten.KeyLeft) {
                sprites.num -= 20
                if sprites.num &lt; MinSprites {
                        sprites.num = MinSprites
                }
        }
        if ebiten.IsKeyPressed(ebiten.KeyRight) {
                sprites.num &#43;= 20
                if MaxSprites &lt; sprites.num {
                        sprites.num = MaxSprites
                }
        }
        sprites.Update()

        if ebiten.IsRunningSlowly() {
                return nil
        }
        w, h := ebitenImage.Size()
        for i := 0; i &lt; sprites.num; i&#43;&#43; {
                s := sprites.sprites[i]
                op.GeoM.Reset()
                op.GeoM.Translate(-float64(w)/2, -float64(h)/2)
                op.GeoM.Rotate(2 * math.Pi * float64(s.angle) / maxAngle)
                op.GeoM.Translate(float64(w)/2, float64(h)/2)
                op.GeoM.Translate(float64(s.x), float64(s.y))
                screen.DrawImage(ebitenImage, op)
        }
        msg := fmt.Sprintf(`FPS: %0.2f
Num of sprites: %d
Press &lt;- or -&gt; to change the number of sprites`, ebiten.CurrentFPS(), sprites.num)
        if err := ebitenutil.DebugPrint(screen, msg); err != nil {
                return err
        }
        return nil
}

func main() {
        var err error
        img, _, err := ebitenutil.NewImageFromFile(&#34;_resources/images/ebiten.png&#34;, ebiten.FilterNearest)
        if err != nil {
                log.Fatal(err)
        }
        w, h := img.Size()
        ebitenImage, _ = ebiten.NewImage(w, h, ebiten.FilterNearest)
        op := &amp;ebiten.DrawImageOptions{}
        op.ColorM.Scale(1, 1, 1, 0.5)
        ebitenImage.DrawImage(img, op)
        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
                a := rand.Intn(maxAngle)
                sprites.sprites[i] = &amp;Sprite{
                        imageWidth:  w,
                        imageHeight: h,
                        x:           x,
                        y:           y,
                        vx:          vx,
                        vy:          vy,
                        angle:       a,
                }
        }
        if err := ebiten.Run(update, screenWidth, screenHeight, 2, &#34;Sprites (Ebiten Demo)&#34;); err != nil {
                log.Fatal(err)
        }
}
</code></pre>

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  <p>© 2013 Hajime Hoshi</p>
  <p>Code is licensed under <a href="https://github.com/hajimehoshi/ebiten/blob/master/LICENSE">the 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>
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doc: Add and remove examples 2016-02-15 16:52:45 +01:00			`<!DOCTYPE html>`
doc: Force HTTPS 2016-08-27 17:58:27 +02:00			`<script src="../scripts/force-https.js"></script>`
doc: Add and remove examples 2016-02-15 16:52:45 +01:00			`<link rel="shortcut icon" href="../favicon.png" type="image/png" >`
			`<link rel="icon" href="../favicon.png" type="image/png" >`
			`<title>Ebiten example - sprites</title>`
doc: Use relative path 2016-08-27 17:48:15 +02:00			`<link rel="stylesheet" href="../stylesheets/bootstrap.min.css">`
			`<link rel="stylesheet" href="../stylesheets/highlight-github.css">`
			`<link rel="stylesheet" href="../stylesheets/ebiten.css">`
doc: Bug fix: wrong path 2016-09-02 18:55:07 +02:00			`<script src="../scripts/googleanalytics.js"></script>`
doc: Apply bootstrap 2016-08-26 19:28:57 +02:00
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doc: Use relative path 2016-08-27 17:48:15 +02:00			`<a class="navbar-brand" href="..">Ebiten</a>`
doc: Apply bootstrap 2016-08-26 19:28:57 +02:00			`</div>`
doc: Fix thumbnail size 2016-08-26 19:37:08 +02:00			`<nav class="collapse navbar-collapse">`
			`<ul class="nav navbar-nav navbar-right">`
			`<li><a href="https://github.com/hajimehoshi/ebiten">GitHub</a></li>`
doc: Force HTTPS 2016-08-27 17:58:27 +02:00			`<li><a href="https://godoc.org/github.com/hajimehoshi/ebiten">GoDoc</a></li>`
doc: Fix thumbnail size 2016-08-26 19:37:08 +02:00			`<li><a href="https://github.com/hajimehoshi/ebiten/wiki">Wiki</a>`
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doc: Apply bootstrap 2016-08-26 19:28:57 +02:00			`</header>`
doc: Add and remove examples 2016-02-15 16:52:45 +01:00
doc: Apply bootstrap 2016-08-26 19:28:57 +02:00			`<main><div class="container">`

doc: Adjust fonts 2016-08-26 20:18:16 +02:00			`<h2>Ebiten example - sprites</h2>`
doc: Apply bootstrap 2016-08-26 19:28:57 +02:00			`<iframe src="sprites.content.html" width="640" height="480"></iframe>`
doc: Highlight code 2016-08-27 07:00:06 +02:00			`<pre><code class="language-go">// +build example`
doc: go generate; Add style.css 2016-08-26 16:33:36 +02:00
			`package main`
doc: Add and remove examples 2016-02-15 16:52:45 +01:00
			`import (`
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`"fmt"`
			`_ "image/png"`
			`"log"`
doc: Update: changed the path for the script location 2017-05-29 15:01:47 +02:00			`"math"`
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`"math/rand"`
Swap import order 2016-02-15 17:13:04 +01:00
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`"github.com/hajimehoshi/ebiten"`
			`"github.com/hajimehoshi/ebiten/ebitenutil"`
doc: Add and remove examples 2016-02-15 16:52:45 +01:00			`)`

			`const (`
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`screenWidth = 320`
			`screenHeight = 240`
doc: Update: changed the path for the script location 2017-05-29 15:01:47 +02:00			`maxAngle = 256`
doc: Add and remove examples 2016-02-15 16:52:45 +01:00			`)`

			`var (`
doc: Update: changed the path for the script location 2017-05-29 15:01:47 +02:00			`ebitenImage *ebiten.Image`
doc: Add and remove examples 2016-02-15 16:52:45 +01:00			`)`

			`type Sprite struct {`
doc: Update docs for Safari (#293) 2016-11-26 16:11:23 +01:00			`imageWidth int`
			`imageHeight int`
			`x int`
			`y int`
			`vx int`
			`vy int`
doc: Update: changed the path for the script location 2017-05-29 15:01:47 +02:00			`angle int`
doc: Add and remove examples 2016-02-15 16:52:45 +01:00			`}`

			`func (s *Sprite) Update() {`
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`s.x += s.vx`
			`s.y += s.vy`
			`if s.x < 0 {`
			`s.x = -s.x`
			`s.vx = -s.vx`
doc: Update docs for Safari (#293) 2016-11-26 16:11:23 +01:00			`} else if screenWidth <= s.x+s.imageWidth {`
			`s.x = 2*(screenWidth-s.imageWidth) - s.x`
			`s.vx = -s.vx`
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`}`
			`if s.y < 0 {`
			`s.y = -s.y`
			`s.vy = -s.vy`
doc: Update docs for Safari (#293) 2016-11-26 16:11:23 +01:00			`} else if screenHeight <= s.y+s.imageHeight {`
			`s.y = 2*(screenHeight-s.imageHeight) - s.y`
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`s.vy = -s.vy`
			`}`
doc: Update: changed the path for the script location 2017-05-29 15:01:47 +02:00			`s.angle++`
			`s.angle %= maxAngle`
doc: Add and remove examples 2016-02-15 16:52:45 +01:00			`}`

			`type Sprites struct {`
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`sprites []*Sprite`
			`num int`
doc: Add and remove examples 2016-02-15 16:52:45 +01:00			`}`

doc: Update docs for Safari (#293) 2016-11-26 16:11:23 +01:00			`func (s *Sprites) Update() {`
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`for _, sprite := range s.sprites {`
			`sprite.Update()`
			`}`
doc: Add and remove examples 2016-02-15 16:52:45 +01:00			`}`

			`const (`
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`MinSprites = 0`
			`MaxSprites = 50000`
doc: Add and remove examples 2016-02-15 16:52:45 +01:00			`)`

doc: Update: changed the path for the script location 2017-05-29 15:01:47 +02:00			`var (`
			`sprites = &Sprites{make([]*Sprite, MaxSprites), 500}`
			`op = &ebiten.DrawImageOptions{}`
			`)`
doc: Add and remove examples 2016-02-15 16:52:45 +01:00
			`func update(screen *ebiten.Image) error {`
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`if ebiten.IsKeyPressed(ebiten.KeyLeft) {`
			`sprites.num -= 20`
			`if sprites.num < MinSprites {`
			`sprites.num = MinSprites`
			`}`
doc: Add and remove examples 2016-02-15 16:52:45 +01:00			`}`
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`if ebiten.IsKeyPressed(ebiten.KeyRight) {`
			`sprites.num += 20`
			`if MaxSprites < sprites.num {`
			`sprites.num = MaxSprites`
			`}`
doc: Add and remove examples 2016-02-15 16:52:45 +01:00			`}`
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`sprites.Update()`
doc: Add and remove examples 2016-02-15 16:52:45 +01:00
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`if ebiten.IsRunningSlowly() {`
			`return nil`
			`}`
doc: Update: changed the path for the script location 2017-05-29 15:01:47 +02:00			`w, h := ebitenImage.Size()`
			`for i := 0; i < sprites.num; i++ {`
			`s := sprites.sprites[i]`
			`op.GeoM.Reset()`
			`op.GeoM.Translate(-float64(w)/2, -float64(h)/2)`
			`op.GeoM.Rotate(2 * math.Pi * float64(s.angle) / maxAngle)`
			`op.GeoM.Translate(float64(w)/2, float64(h)/2)`
			`op.GeoM.Translate(float64(s.x), float64(s.y))`
			`screen.DrawImage(ebitenImage, op)`
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`}`
			msg := fmt.Sprintf(`FPS: %0.2f
doc: Add and remove examples 2016-02-15 16:52:45 +01:00			`Num of sprites: %d`
doc: Update: changed the path for the script location 2017-05-29 15:01:47 +02:00			Press <- or -> to change the number of sprites`, ebiten.CurrentFPS(), sprites.num)
			`if err := ebitenutil.DebugPrint(screen, msg); err != nil {`
			`return err`
			`}`
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`return nil`
doc: Add and remove examples 2016-02-15 16:52:45 +01:00			`}`

			`func main() {`
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`var err error`
doc: Update: changed the path for the script location 2017-05-29 15:01:47 +02:00			`img, _, err := ebitenutil.NewImageFromFile("_resources/images/ebiten.png", ebiten.FilterNearest)`
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`if err != nil {`
			`log.Fatal(err)`
			`}`
doc: Update: changed the path for the script location 2017-05-29 15:01:47 +02:00			`w, h := img.Size()`
			`ebitenImage, _ = ebiten.NewImage(w, h, ebiten.FilterNearest)`
			`op := &ebiten.DrawImageOptions{}`
			`op.ColorM.Scale(1, 1, 1, 0.5)`
			`ebitenImage.DrawImage(img, op)`
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`for i := range sprites.sprites {`
			`w, h := ebitenImage.Size()`
			`x, y := rand.Intn(screenWidth-w), rand.Intn(screenHeight-h)`
			`vx, vy := 2rand.Intn(2)-1, 2rand.Intn(2)-1`
doc: Update: changed the path for the script location 2017-05-29 15:01:47 +02:00			`a := rand.Intn(maxAngle)`
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`sprites.sprites[i] = &Sprite{`
doc: Update docs for Safari (#293) 2016-11-26 16:11:23 +01:00			`imageWidth: w,`
			`imageHeight: h,`
			`x: x,`
			`y: y,`
			`vx: vx,`
			`vy: vy,`
doc: Update: changed the path for the script location 2017-05-29 15:01:47 +02:00			`angle: a,`
doc: Change indent size 4 -> 8 2016-08-26 22:36:52 +02:00			`}`
			`}`
			`if err := ebiten.Run(update, screenWidth, screenHeight, 2, "Sprites (Ebiten Demo)"); err != nil {`
			`log.Fatal(err)`
			`}`
doc: Add and remove examples 2016-02-15 16:52:45 +01:00			`}`
			`</code></pre>`

doc: Apply bootstrap 2016-08-26 19:28:57 +02:00			`</div></main>`

			`<footer><div class="container">`
			`<p>© 2013 Hajime Hoshi</p>`
doc: Add 'the' 2016-08-28 00:10:41 +02:00			`<p>Code is licensed under <a href="https://github.com/hajimehoshi/ebiten/blob/master/LICENSE">the Apache License 2.0</a>.</p>`
doc: Apply bootstrap 2016-08-26 19:28:57 +02:00			`<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>`
doc: Add and remove examples 2016-02-15 16:52:45 +01:00
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