Ellipse Path Closing with Trim Paths
There seems to be a bug when working with parametric ellipse paths in tandem with trim paths.
It only seems to occur when the Start or End properties in the trim path are set to 50%, while the other is set to 0%. I've attached a couple videos for reference.
When the ellipse path position is adjusted the ellipse path will occasionally close itself, resulting in an unwanted half-circle. The half circle is a result of the Start property set to 0%, and the End property set to 50%. However, when the values are swapped (Start: 50%, End: 0%) it results in a completely different shape entirely.
Changing the group position in the layer doesn't cause this, and neither does the layer position. Other values for Start and End didn't seem to cause the issue either, only the 50/0 combination.
Some known workarounds include:
- Setting the value to something very close but not visibly different, such as 50.0001%
- Using an if/else expression to prevent a frame landing on 50% if the property is animated.
- Adjusting position with the group transform or layer transform properties
This has been tested on multiple machines running the latest version of After Effects (15.1.2), and while the issue occurs at varying positions, it seems to always result in the same shapes being created.
Thank you for bringing this to our attention, we've been able to reproduce the bug thanks to your examples and will be forwarding it to our developers for investigation.