Trim path

[S_ A]

Francis Bacon once said, “A Prudent Question is One-half of Wisdom.”.

After spending hours learning about the Trim path on the web I ask myself what is the necessity of having a start and end in the trim path option. They both do the same just oppositely. 

Can anyone make sense of having this two? I find it very difficult to understand. Like Entire Physics break down when it comes to Blackhole My entire enthusiasm about AE collapse when it comes to Trim path!

I do not understand TRIM PATH.

Please help. :'( 😞 

[Jose Panadero]

Think that every path has an start vertex and end vertex (the first and end points you draw). Start and end parameters in Trim Path refer exactly to this. If start and end are 0 and 100, a complete stroke will be shown. If start is 20, the first 20% of your stroke will be trimmed. If end is 80, then the last 20% of your path will be trimmed. If End is lower than Start then what is happening is that the stroke will be shown in reverse direction. Hope this help

[S_ A]

Wow! Nobody says all this in all those tutorials! I think I understand what you said! Thank you so much.

[thepixelsmith]

To add on to what Jose said.

A path is either open or closed. An open path is a line, it has a recognizable start and end point. These points are based on the order in which the vertices (anchor points) of the path are created, first, second, third, etc. A closed path is a shape, think a circle or rectangle. The first vertex of a closed path looks different from the others, it usually has a hollow square around the smaller vertex square.

In After Effects the first vertex of a path can be changed by selected a vertex and choosing Layer > Mask and Shape Path > Set First Vertex (or right-clicking to get the same menu). This would allow you to control where on a path the Trim path efffect starts so that you can control the look of the animation.

First Vertex

Another use of the trim path Start and End properties is if you want to animate the visual movement of a line (usually just a stroke) along a path. 

By changing the Start and/or End properties and animating the Offset property the stroke will travel along the path from beginning to end. 

[S_ A]

Hello, Thank you so much for this explanation. I never think like that. I concentrated on the purpose of  start and ending only, not on the Stroke/Path itself. You made it very clear what those start and end are for. Thank you again,