gg/ox/asprite.go

package ox

//import "time"
import "surdeus.su/core/gg"
import "surdeus.su/core/gg/ax"

var _ = gg.Drawer(&AnimatedSprite{})
// The type implements animated sprites.
type AnimatedSprite struct {
	Sprite

	animations ax.AnimationSet
	animationId ax.AnimationID

	currentFrame int

	// This is time between animation frames, not
	// engine ones.
	timeBetweenFrames gg.Duration
	duration gg.Duration
}

func NewAnimatedSprite(
	animations ax.AnimationSet,
	timeBetweenFrames gg.Duration,
) AnimatedSprite {
	ret := AnimatedSprite{}
	ret.animations = animations
	ret.timeBetweenFrames = timeBetweenFrames
	return ret
}

// Change current animation to the specified one.
func (as *AnimatedSprite) Animate(id ax.AnimationID) bool {
	if as.animationId == id {
		return true
	}
	_, ok := as.animations[id]
	if ok {
		as.duration = 0
		as.animationId = id
	}
	return ok
}

func (as *AnimatedSprite) Draw(c gg.Context) *gg.Drawing {
	as.duration += c.Engine().DrawDT()

	frames := as.animations[as.animationId]
	fullTime := gg.Duration(len(frames)) * as.timeBetweenFrames
	if as.duration > fullTime {
		as.duration -= fullTime
	}

	as.Images[0] = frames[
		(as.duration/as.timeBetweenFrames) %
			gg.Duration(len(frames)),
	]

	return as.Sprite.Draw(c)
}