MORE MESSING AROUND

internal/ui/tween.go

@@ -1,11 +1,39 @@
 package ui
 
-type num interface {
-	int32 | float32
+import (
+	"math"
+	"time"
+)
+
+type Tween struct {
+	startVal  int32
+	startTime time.Time
+	dif       int32
+	dur       time.Duration
 }
 
-type Tween[T num] struct {
-	start    T
-	nextMult float32
-	end      T
+func NewTween(startVal, endVal int32, duration time.Duration) *Tween {
+	return &Tween{
+		startVal:  startVal,
+		dif:       endVal - startVal,
+		dur:       duration,
+		startTime: time.Now().Round(time.Millisecond),
+	}
+}
+
+func (t *Tween) CurVal() int32 {
+	since := time.Now().Round(time.Millisecond).Sub(t.startTime)
+	if since <= 0 {
+		return t.startVal
+	}
+	if since >= t.dur {
+		return t.startVal + t.dif
+	}
+	m := float32(since.Milliseconds()) / float32(t.dur.Milliseconds())
+	m = -1 * float32(math.Log10(-.9*float64(m)+1))
+	return t.startVal + int32(math.Round(float64(float32(t.dif)*m)))
+}
+
+func (t *Tween) Ended() bool {
+	return time.Now().Round(time.Millisecond).Sub(t.startTime) >= t.dur
 }