Object with follow-path constraint jumps off path, continuing slightly displaced. #68538

New Issue

Jaggz H · 2019-08-11T11:29:08+02:00

Jaggz H commented

2019-08-11 11:29:08 +02:00

Operating system: Linux, Debian 10 (Buster)
Graphics card: Secret (970)

Broken: (example: 2.81 alpha, 2019-08-09 a571ff2c16, master as found on the splash screen)
Worked: Unsure

Empty leaps off path.

Load attached blend. Move forward about 12 or so frames and you'll see the Empty jump off the path a bit. Increasing the curve resolution draws it increasingly closer to the visible path.cam-follow-path.blend

Operating system: Linux, Debian 10 (Buster) Graphics card: Secret (970) Broken: (example: 2.81 alpha, 2019-08-09 a571ff2c16c6, master as found on the splash screen) Worked: Unsure Empty leaps off path. Load attached blend. Move forward about 12 or so frames and you'll see the Empty jump off the path a bit. Increasing the curve resolution draws it increasingly closer to the visible path.[cam-follow-path.blend](https://archive.blender.org/developer/F7658814/cam-follow-path.blend)

Jaggz H commented

2019-08-11 11:29:09 +02:00

Added subscriber: @jaggz

Jaggz H changed title from ~~Object with follo-path constraint chooses the path less traveled by.~~ to Object with follow-path constraint chooses the path less traveled by.

2019-08-11 11:30:00 +02:00

Jaggz H commented

2019-08-11 11:39:10 +02:00

Oh, please note that I also keyed the Offset on the Empties (and set Fixed Position).

...and here's a video of it, for those who want to experience it without fiddling with a .blend.

https://www.youtube.com/watch?v=GreYnA4CWVo

Oh, please note that I also keyed the Offset on the Empties (and set Fixed Position). ...and here's a video of it, for those who want to experience it without fiddling with a .blend. https://www.youtube.com/watch?v=GreYnA4CWVo

Jaggz H changed title from ~~Object with follow-path constraint chooses the path less traveled by.~~ to Object with follow-path constraint jumps off path, continuing slightly displaced.

2019-08-12 03:12:47 +02:00

Germano Cavalcante commented

2019-12-30 13:49:12 +01:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2019-12-30 13:49:12 +01:00

Changed status from 'Needs Triage' to: 'Confirmed'

Germano Cavalcante commented

2019-12-30 13:49:12 +01:00

I can confirm the problem.
I believe the problem is in where_on_path.
Apparently the factor is calculated as if each segment of the curve had an equivalent length.
https://developer.blender.org/diffusion/B/browse/master/source/blender/blenkernel/intern/anim.c$461

I can confirm the problem. I believe the problem is in `where_on_path`. Apparently the factor is calculated as if each segment of the curve had an equivalent length. https://developer.blender.org/diffusion/B/browse/master/source/blender/blenkernel/intern/anim.c$461

Sybren A. Stüvel commented

2020-01-14 14:55:10 +01:00

Added subscriber: @dr.sybren

Sybren A. Stüvel commented

2020-01-14 14:55:10 +01:00

This is very old code, so Blender has been working like this for a long time. It would be nice to properly fix it at some point, but at this moment it's a Known Issue.

Philipp Oeser removed the

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Object with follow-path constraint jumps off path, continuing slightly displaced. #68538