package sprites import ( "github.com/hajimehoshi/go-ebiten" "github.com/hajimehoshi/go-ebiten/graphics" "github.com/hajimehoshi/go-ebiten/graphics/matrix" "image" "math/rand" "os" "time" ) const ( ebitenTextureWidth = 57 ebitenTextureHeight = 26 ) type Sprite struct { width int height int ch chan bool x int y int vx int vy int } func newSprite(screenWidth, screenHeight, width, height int) *Sprite { maxX := screenWidth - width maxY := screenHeight - height sprite := &Sprite{ width: width, height: height, ch: make(chan bool), x: rand.Intn(maxX), y: rand.Intn(maxY), vx: rand.Intn(2)*2 - 1, vy: rand.Intn(2)*2 - 1, } go sprite.update(screenWidth, screenHeight) return sprite } func (sprite *Sprite) update(screenWidth, screenHeight int) { maxX := screenWidth - sprite.width maxY := screenHeight - sprite.height for { <-sprite.ch sprite.x += sprite.vx sprite.y += sprite.vy if sprite.x < 0 || maxX <= sprite.x { sprite.vx = -sprite.vx } if sprite.y < 0 || maxY <= sprite.y { sprite.vy = -sprite.vy } sprite.ch <- true } } func (sprite *Sprite) Update() { sprite.ch <- true <-sprite.ch } type Sprites struct { ebitenTextureID graphics.TextureID sprites []*Sprite } func New() *Sprites { return &Sprites{} } func (game *Sprites) Init(tf graphics.TextureFactory) { file, err := os.Open("images/ebiten.png") if err != nil { panic(err) } defer file.Close() img, _, err := image.Decode(file) if err != nil { panic(err) } if game.ebitenTextureID, err = tf.NewTextureFromImage(img); err != nil { panic(err) } } func (game *Sprites) Update(context ebiten.GameContext) { if game.sprites == nil { game.sprites = []*Sprite{} for i := 0; i < 100; i++ { sprite := newSprite( context.ScreenWidth(), context.ScreenHeight(), ebitenTextureWidth, ebitenTextureHeight) game.sprites = append(game.sprites, sprite) } } for _, sprite := range game.sprites { sprite.Update() } } func (game *Sprites) Draw(g graphics.Context) { g.Fill(128, 128, 255) // Draw the sprites locations := make([]graphics.TexturePart, 0, len(game.sprites)) for _, sprite := range game.sprites { location := graphics.TexturePart{ LocationX: sprite.x, LocationY: sprite.y, Source: graphics.Rect{ 0, 0, ebitenTextureWidth, ebitenTextureHeight, }, } locations = append(locations, location) } geometryMatrix := matrix.IdentityGeometry() g.DrawTextureParts(game.ebitenTextureID, locations, geometryMatrix, matrix.IdentityColor()) } func init() { rand.Seed(time.Now().UnixNano()) }