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examples/perspective: Refactoring

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This commit is contained in:
Hajime Hoshi 2018-01-30 01:54:00 +09:00
parent c4faf5b12c
commit 531e661f0b
1 changed files with 14 additions and 6 deletions
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20
examples/perspective/main.go
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@ -38,17 +38,25 @@ func update(screen *ebiten.Image) error {
if ebiten.IsRunningSlowly() {
return nil
}
// Split the image into horizontal lines and draw them with different scales.
op := &ebiten.DrawImageOptions{}
w, h := gophersImage.Size()
for i := 0; i < h; i++ {
op.GeoM.Reset()
width := w + i*3/4
x := ((h - i) * 3 / 4) / 2
op.GeoM.Scale(float64(width)/float64(w), 1)
op.GeoM.Translate(float64(x), float64(i))
maxWidth := float64(w) + float64(h)*3/4
op.GeoM.Translate(-maxWidth/2, -float64(h)/2)
// Move the image's center to the upper-left corner.
op.GeoM.Translate(-float64(w)/2, -float64(h)/2)
// Scale each lines and adjust the position.
lineW := w + i*3/4
x := -float64(lineW) / float64(w) / 2
op.GeoM.Scale(float64(lineW)/float64(w), 1)
op.GeoM.Translate(x, float64(i))
// Move the image's center to the screen's center.
op.GeoM.Translate(screenWidth/2, screenHeight/2)
r := image.Rect(0, i, w, i+1)
op.SourceRect = &r
screen.DrawImage(gophersImage, op)