53 lines
1.1 KiB
Go
53 lines
1.1 KiB
Go
package engine
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import "encoding/gob"
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// Ensure Anim satisfies Animer.
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var _ Animer = &Anim{}
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func init() {
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gob.Register(&Anim{})
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}
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// AnimFrame describes a frame in an animation.
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type AnimFrame struct {
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Frame int // show this frame
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Duration int // for this long, in ticks
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}
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// Anim is n animation being displayed, together with the current state.
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type Anim struct {
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Frames []AnimFrame
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OneShot bool
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Index int
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Ticks int
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}
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// Copy makes a shallow copy of the anim.
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func (a *Anim) Copy() *Anim {
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a2 := *a
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return &a2
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}
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// CurrentFrame returns the frame number for the current index.
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func (a *Anim) CurrentFrame() int { return a.Frames[a.Index].Frame }
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// Reset resets both Index and Ticks to 0.
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func (a *Anim) Reset() { a.Index, a.Ticks = 0, 0 }
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// Update increments the tick count and advances the frame if necessary.
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func (a *Anim) Update() error {
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a.Ticks++
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if a.OneShot && a.Index == len(a.Frames)-1 {
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// on the last frame of a one shot so remain on final frame
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return nil
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}
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if a.Ticks >= a.Frames[a.Index].Duration {
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a.Ticks = 0
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a.Index++
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}
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if !a.OneShot && a.Index >= len(a.Frames) {
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a.Index = 0
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}
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return nil
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}
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