Caleb Gardner
40 lines
837 B
Go
40 lines
837 B
Go
package ui
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import (
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"math"
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"time"
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)
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type Tween struct {
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startVal int32
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startTime time.Time
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dif int32
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dur time.Duration
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}
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func NewTween(startVal, endVal int32, duration time.Duration) *Tween {
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return &Tween{
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startVal: startVal,
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dif: endVal - startVal,
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dur: duration,
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startTime: time.Now().Round(time.Millisecond),
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}
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}
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func (t *Tween) CurVal() int32 {
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since := time.Now().Round(time.Millisecond).Sub(t.startTime)
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if since <= 0 {
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return t.startVal
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}
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if since >= t.dur {
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return t.startVal + t.dif
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}
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m := float32(since.Milliseconds()) / float32(t.dur.Milliseconds())
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m = -1 * float32(math.Log10(-.9*float64(m)+1))
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return t.startVal + int32(math.Round(float64(float32(t.dif)*m)))
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}
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func (t *Tween) Ended() bool {
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return time.Now().Round(time.Millisecond).Sub(t.startTime) >= t.dur
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}
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