47 lines
1.2 KiB
Go
47 lines
1.2 KiB
Go
package engine
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import (
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"image"
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"github.com/hajimehoshi/ebiten/v2"
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)
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var _ interface {
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Prepper
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Scanner
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} = &Sheet{}
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// Sheet handles images that consist of a grid of equally sized regions
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// (cells) and can produce subimages for the cell at an index. This is useful
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// for various applications such as sprite animation and tile maps. Additionally
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// each sheet carries a collection of animations that use the sheet.
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type Sheet struct {
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AnimDefs map[string]*AnimDef
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CellSize image.Point
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Src ImageRef
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w int // width as measured in number of cells
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}
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// NewAnim returns a new Anim for the given key, or nil if not found in
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// AnimDefs.
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func (s *Sheet) NewAnim(key string) *Anim {
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return s.AnimDefs[key].NewAnim()
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}
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// Prepare computes the width of the image (in cells).
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func (s *Sheet) Prepare(*Game) error {
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s.w, _ = s.Src.Image().Size()
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s.w /= s.CellSize.X
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return nil
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}
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// Scan returns the Src.
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func (s *Sheet) Scan() []interface{} { return []interface{}{&s.Src} }
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// SubImage returns an *ebiten.Image corresponding to the given cell index.
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func (s *Sheet) SubImage(i int) *ebiten.Image {
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p := cmul(image.Pt(i%s.w, i/s.w), s.CellSize)
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r := image.Rectangle{p, p.Add(s.CellSize)}
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return s.Src.Image().SubImage(r).(*ebiten.Image)
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}
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