package rotating import ( "github.com/hajimehoshi/go.ebiten/graphics" "github.com/hajimehoshi/go.ebiten/graphics/matrix" "image" "image/color" _ "image/png" "math" "os" ) type Rotating struct { ebitenTexture graphics.Texture x int } func New() *Rotating { return &Rotating{} } func (game *Rotating) ScreenWidth() int { return 256 } func (game *Rotating) ScreenHeight() int { return 240 } func (game *Rotating) Fps() int { return 60 } func (game *Rotating) Init(tf graphics.TextureFactory) { file, err := os.Open("ebiten.png") if err != nil { panic(err) } defer file.Close() img, _, err := image.Decode(file) if err != nil { panic(err) } if game.ebitenTexture, err = tf.NewTextureFromImage(img); err != nil { panic(err) } } func (game *Rotating) Update() { game.x++ } func (game *Rotating) Draw(g graphics.GraphicsContext, offscreen graphics.Texture) { g.Fill(&color.RGBA{R: 128, G: 128, B: 255, A: 255}) geometryMatrix := matrix.IdentityGeometry() tx, ty := float64(game.ebitenTexture.Width), float64(game.ebitenTexture.Height) geometryMatrix.Translate(-tx/2, -ty/2) geometryMatrix.Rotate(float64(game.x) * 2 * math.Pi / float64(game.Fps()*10)) geometryMatrix.Translate(tx/2, ty/2) centerX := float64(game.ScreenWidth()) / 2 centerY := float64(game.ScreenHeight()) / 2 geometryMatrix.Translate(centerX-tx/2, centerY-ty/2) g.DrawTexture(game.ebitenTexture.ID, geometryMatrix, matrix.IdentityColor()) }