I have used the Write-on effect for this but I find I like the Stroked Path better. Here are the detailed steps I used to animate a line on a map:
Add a Shape layer and select it.
- On the toolbar:
Select the Pen tool. and to the right side of the tool bar
Set the Fill Color to NONE
Set the Stroke to be a solid color, this will be the color of your dots.
Set the Stroke width, 10 is a good starting point.
Enable the RotoBezier option.
- Hover the mouse pointer over the map at the starting point for the line, it should be a Pen shape. Click to set the starting point and then move the mouse to the next map position and click. Do this until the line you wish the path to follow is complete.
Twirl down the Shape layer and then “Contents” and then the “Shape 1” and finally the “Stroke 1”
- Set the color for the line and width desired.
- If you want dashes rather than a solid line: (1) Twirl down the “Dashes” control and adjust the size of the Dash and (2) “Line Cap” and “Line Join” offer options on the look of the dashes.
To animate the line:
- Click the “Add” button on the “Contents” line and select “Trim Paths”
- Twirl down “Trim Paths 1”
- Make sure the Current Time Indicator is at the beginning of the clip
- Click the stopwatch of the “End” control to begin keyframes and set the value to 0%.
- Move the current time indicator to the end of the clip and set the value of the
- “end” control to 100%.
- To control how fast the animation moves to specific points within the clip, add a keyframe at the desired point and set the “End” value so as to move the dotted line to that point. There is a little t
rial and error with this but it gives you a very high level of control and is worth effort.