# Animate Koch curve generation and include a transition effect

Recently, I saw two kinds of animation of Koch curve iteration generation.

I don't know how to make this effect, now I can only do this

Clear[koch];
koch[{A_, B_}] :=
Partition[
{A, (2 A + B)/3, (A + B)/2 + Cross[B - A]/(2 Sqrt[3]),(A + 2 B)/3, B},
2, 1];
Manipulate[
Graphics[Line /@ Nest[Join @@ koch /@ # &, N @ {{{-1, 0}, {1, 0}}}, n]],
{n, 1, 4, 1}]


Question: How to make animation with transition effect like that?

Isn't the fastest but there is not much to see for higher iterations anyway. Let me know if anything is unclear.

Manipulate[
Graphics[
Line[
{#, #2, Dynamic[.5 (#5 + #) + (t + 1 - n) (#3 - .5 (# + #5))], #4, #5}
] & @@@ Partition[KochCurve[n][[1]], 5, 4]
, PlotRange -> {{0, 1}, {0, .3}}
, ImageSize -> 500
],
{{n, 1}, None},
{t, 0, 5, .1, TrackingFunction :> ((t = #; n = Ceiling[t]) &)}
]


Manipulate[Graphics[{
[email protected],
Line[
{{#, #2, Dynamic@RotationTransform[-Pi/3. (n - t), #2][#3]},
{#5, #4, Dynamic@RotationTransform[Pi/3. (n - t), #4][#3]}
}
] & @@@ Partition[KochCurve[n][[1]], 5, 4]
}, PlotRange -> {{0, 1}, {0, .3}}, ImageSize -> 500], {{n, 1},
None}, {t, 0, 5, .1,
TrackingFunction :> ((t = #; n = Ceiling[t]) &)}]