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Add Transform field to Scene

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This commit is contained in:
Josh Deprez 2021-07-30 14:36:11 +10:00 committed by Josh Deprez
parent 14407fe47d
commit ed5092cc3e
1 changed files with 17 additions and 14 deletions
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29
engine/scene.go
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@ -24,12 +24,15 @@ type ZPositioner interface {
// Scene manages drawing and updating a bunch of components. // Scene manages drawing and updating a bunch of components.
type Scene struct { type Scene struct {
Components []interface{} Components []interface{}
Transform ebiten.GeoM
needsSort bool needsSort bool
} }
// Draw draws all components in order. // Draw draws all components in order.
func (l *Scene) Draw(screen *ebiten.Image, geom ebiten.GeoM) { func (s *Scene) Draw(screen *ebiten.Image, geom ebiten.GeoM) {
for _, i := range l.Components { geom.Concat(s.Transform)
for _, i := range s.Components {
if d, ok := i.(Drawer); ok { if d, ok := i.(Drawer); ok {
d.Draw(screen, geom) d.Draw(screen, geom)
} }
@ -37,18 +40,18 @@ func (l *Scene) Draw(screen *ebiten.Image, geom ebiten.GeoM) {
} }
// SetNeedsSort informs l that its layers may be out of order. // SetNeedsSort informs l that its layers may be out of order.
func (l *Scene) SetNeedsSort() { func (s *Scene) SetNeedsSort() {
l.needsSort = true s.needsSort = true
} }
// sortByZ sorts the components by Z position. // sortByZ sorts the components by Z position.
// Stable sort is used to avoid Z-fighting among layers without a Z, or // Stable sort is used to avoid Z-fighting among layers without a Z, or
// among those with equal Z. All non-ZPositioners are sorted first. // among those with equal Z. All non-ZPositioners are sorted first.
func (l *Scene) sortByZ() { func (s *Scene) sortByZ() {
l.needsSort = false s.needsSort = false
sort.SliceStable(l.Components, func(i, j int) bool { sort.SliceStable(s.Components, func(i, j int) bool {
a, aok := l.Components[i].(ZPositioner) a, aok := s.Components[i].(ZPositioner)
b, bok := l.Components[j].(ZPositioner) b, bok := s.Components[j].(ZPositioner)
if aok && bok { if aok && bok {
return a.Z() < b.Z() return a.Z() < b.Z()
} }
@ -57,16 +60,16 @@ func (l *Scene) sortByZ() {
} }
// Update calls Update on all Updater components. // Update calls Update on all Updater components.
func (l *Scene) Update() error { func (s *Scene) Update() error {
for _, c := range l.Components { for _, c := range s.Components {
if u, ok := c.(Updater); ok { if u, ok := c.(Updater); ok {
if err := u.Update(); err != nil { if err := u.Update(); err != nil {
return err return err
} }
} }
} }
if l.needsSort { if s.needsSort {
l.sortByZ() s.sortByZ()
} }
return nil return nil
} }