70 lines
1.6 KiB
Go
70 lines
1.6 KiB
Go
package engine
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import (
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"encoding/gob"
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"github.com/hajimehoshi/ebiten/v2"
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)
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var _ interface {
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Drawer
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DrawManager
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Scanner
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} = &DrawDFS{}
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func init() {
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gob.Register(&DrawDFS{})
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}
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// DrawDFS is a DrawManager that does not add any structure. Components are
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// drawn in the order in which they are encountered by a depth-first search
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// through the game tree, without any extra sorting based on Z values or
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// consideration for DrawOrderer).
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type DrawDFS struct {
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Child interface{}
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Hides
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}
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func (d *DrawDFS) Draw(screen *ebiten.Image, opts *ebiten.DrawImageOptions) {
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if d.Hidden() {
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return
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}
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d.drawRecursive(d.Child, screen, *opts)
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}
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// ManagesDrawingSubcomponents is present so DrawDFS is recognised as a
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// DrawManager.
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func (DrawDFS) ManagesDrawingSubcomponents() {}
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func (d *DrawDFS) drawRecursive(component interface{}, screen *ebiten.Image, opts ebiten.DrawImageOptions) {
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// Hidden? stop drawing
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if h, ok := component.(Hider); ok && h.Hidden() {
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return
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}
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// Has a transform? apply to opts
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if tf, ok := component.(Transformer); ok {
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opts = concatOpts(tf.Transform(), opts)
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}
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// Does it draw itself? Draw
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if dr, ok := component.(Drawer); ok {
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dr.Draw(screen, &opts)
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}
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// Is it a DrawManager? It manages drawing all its subcomponents.
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if _, ok := component.(DrawManager); ok {
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return
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}
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// Has subcomponents? recurse
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if sc, ok := component.(Scanner); ok {
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sc.Scan(func(x interface{}) error {
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d.drawRecursive(x, screen, opts)
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return nil
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})
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}
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}
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// Scan visits d.Child.
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func (d *DrawDFS) Scan(visit func(interface{}) error) error {
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return visit(d.Child)
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}
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func (d *DrawDFS) String() string { return "DrawDFS" }
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