ebiten/example/game/rotating/rotating.go
2013-10-21 22:18:10 +09:00

63 lines
1.4 KiB
Go

package rotating
import (
"github.com/hajimehoshi/go-ebiten"
"github.com/hajimehoshi/go-ebiten/graphics"
"github.com/hajimehoshi/go-ebiten/graphics/matrix"
"image"
_ "image/png"
"math"
"os"
)
const (
ebitenTextureWidth = 57
ebitenTextureHeight = 26
)
type Rotating struct {
ebitenTextureId graphics.TextureId
x int
geometryMatrix matrix.Geometry
}
func New() *Rotating {
return &Rotating{}
}
func (game *Rotating) InitTextures(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 *Rotating) Update(context ebiten.GameContext) {
game.x++
game.geometryMatrix = matrix.IdentityGeometry()
tx, ty := float64(ebitenTextureWidth), float64(ebitenTextureHeight)
game.geometryMatrix.Translate(-tx/2, -ty/2)
game.geometryMatrix.Rotate(float64(game.x) * 2 * math.Pi / float64(ebiten.FPS*10))
game.geometryMatrix.Translate(tx/2, ty/2)
centerX := float64(context.ScreenWidth()) / 2
centerY := float64(context.ScreenHeight()) / 2
game.geometryMatrix.Translate(centerX-tx/2, centerY-ty/2)
}
func (game *Rotating) Draw(g graphics.Context) {
g.Fill(128, 128, 255)
g.DrawTexture(game.ebitenTextureId,
game.geometryMatrix,
matrix.IdentityColor())
}