Using trim paths to animate in two directions

[Portland_023]

I am trying to animate a line using trim paths. I want the line to animate from the centre out i.e. from the centre animating both left and right. Is there anyway to do this?

[Mylenium]

Split the path at the center and apply two separate strokes and trim operators. Everything else would be a nightmare, since there's no easy way to calculate the percentages.

Mylenium

[Rick Gerard]

Trim Paths give you the ability to animate the start and end of a line as well as the offset. The start and end values are percentages so the math is easy. An offset of - 180º makes the start or end animation begin exactly halfway through the line.

By far the easiest way to have a line form from both ends and meet in the exact middle or grow from the middle is to animate the End from zero to 100% and the offset from 0º to -180º to make a line start at the end or animate the Start from 100% to 0% and the Offset from 0º to -180º. 

The other way would be to animate the Start from 50% to 0% and the End from 50% to 100%. Either one of these techniques will do what you ask and you can offset the meeting point or starting point by simply adjusting the percentages.

[j_v_a]

this is very helpful, appreciate the time taken to walk through this

[d-korolkov]

1) add trim path to the line
2) dublicate the line
3) set 1st line trim keyframes Start 50%->0%
4) set 2st line trim keyframes  End 50%->100%
voilàa

[drewa63500664]

Make a line.

Add trim paths.

Set two keyframes. 1st at 0%, 2nd at %100.

Duplicate line.

Flip horizontal.

Done.