66 lines
1.4 KiB
Go
66 lines
1.4 KiB
Go
package engine
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import (
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"sort"
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"github.com/hajimehoshi/ebiten/v2"
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)
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// Updater is a component that can update. Update is called repeatedly.
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type Updater interface {
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Update() error
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}
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// Drawer is a component that can draw itself. Draw is called often.
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// DrawAfter is used to reorder components.
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type Drawer interface {
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Draw(*ebiten.Image)
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Z() float64
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}
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// Game implements the ebiten methods using a collection of components.
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type Game struct {
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ScreenWidth int
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ScreenHeight int
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Components []interface{}
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}
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// Update calls Update on all Updater components.
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func (g *Game) Update() error {
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for _, c := range g.Components {
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if u, ok := c.(Updater); ok {
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if err := u.Update(); err != nil {
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return err
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}
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}
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}
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return nil
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}
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// Draw calls Draw on all Drawer components.
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func (g *Game) Draw(screen *ebiten.Image) {
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for _, c := range g.Components {
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if d, ok := c.(Drawer); ok {
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d.Draw(screen)
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}
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}
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}
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// Layout returns the configured screen width/height.
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func (g *Game) Layout(outsideWidth, outsideHeight int) (w, h int) {
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return g.ScreenWidth, g.ScreenHeight
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}
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// Sort sorts the components by Z position.
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// Non-Drawers are sorted before all Drawers.
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func (g *Game) Sort() {
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// Stable sort to avoid z-fighting (among Non-Drawers and equal Drawers)
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sort.SliceStable(g.Components, func(i, j int) bool {
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a, aok := g.Components[i].(Drawer)
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b, bok := g.Components[j].(Drawer)
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if aok && bok {
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return a.Z() < b.Z()
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}
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return !aok && bok
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})
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}
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