Completing trim path through the center of the stem(or line)

[NicBoy]

Hi, I create a shape layer from the illustrator layer(flower stem),

When I add a trim path to the shape layer, and adding keyframe on start, (0 to 100), the stroke line become growing around the stem,

I want a stem which complete from 0 to 100 through the center of the line, not around the line or stem,

[Mylenium · Accepted solution]

Don't use a Trim Paths modifier. Either create another rectangle and use a Merge Paths Modifier in Subtract mode or even simpler simply place the stem on it's own layer and use a good old Linear Wipe effect. No need to make things complicated just to look smart.

Mylenium

[NicBoy]

Thank You @Mylenium 

Do you know how I can make small stars around the growing stem?

[Rick Gerard]

Your cropped screenshot does not tell the whole story. It looks like the flower stem was created with a brunch. You ended up with a closed path instead of a single path when you converted the Vector layer to a shape layer. 

If you have to use the brush, then the proper workflow would be to duplicate the path in Illustrator, move the duplicate to another layer, remove the brush stroke from the duplicate, and name the new layer Track Matte. Import as a composition, open the comp, only convert the Track Matte layer to a shape layer, and you should end up with a single path. You can make the brush stroke wide enough to cover the flower stem and then use the layer as a track matte for the stem. 

That workflow will preserve brush strokes, gradients, and any other fancy stuff you did in AI that gets fouled up when you convert complex vector layers to shape layers.