42 lines
994 B
Go
42 lines
994 B
Go
package engine
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// Anim is an "instance" of an AnimDef: an animation being displayed,
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// together with the current state.
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type Anim struct {
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Def *AnimDef
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Index int
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Ticks int
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}
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func (a *Anim) CurrentFrame() int { return a.Def.Frames[a.Index].Frame }
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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.Def.OneShot && a.Index == len(a.Def.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.Def.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.Def.OneShot && a.Index >= len(a.Def.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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// AnimDef describes an animation (sequence of frames and timings).
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type AnimDef struct {
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Frames []AnimFrame
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OneShot bool
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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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