Extrapolate within the Transformation Constraint not working correctly #74988

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Mat Brady · 2020-03-20T23:21:09+01:00

Mat Brady commented

2020-03-20 23:21:09 +01:00

System Information
Operating system: mac0S Catalina
Graphics card: NVIDIA GeForce GT 750M 2 GB

Blender Version
Broken: 2.82a this was downloaded and tested with just prior to bug report
Worked: 2.79b

Short description of error
While rotating a shape around a path the extrapolate doesn't seem to work as it did in 2.79b. The shape snaps back to its looped measurement.

Exact steps for others to reproduce the error
Open the file up and rotate the circle in the middle. This will show you what it's doing incorrectly.
https://drive.google.com/open?id=1ly1o5YdeOocDNKCiNDynGXk_HA4JaC77

This was created by following this simple YouTube tutorial (which worked perfectly in 2.79b).
https://youtu.be/a9nGRM6q1Ik?list=LLIHO4S6ShYCr6Gr6zWF2u4Q

Email me with further questions or info at: matbrady1@gmail.com

**System Information** Operating system: mac0S Catalina Graphics card: NVIDIA GeForce GT 750M 2 GB **Blender Version** Broken: 2.82a this was downloaded and tested with just prior to bug report Worked: 2.79b **Short description of error** While rotating a shape around a path the extrapolate doesn't seem to work as it did in 2.79b. The shape snaps back to its looped measurement. **Exact steps for others to reproduce the error** Open the file up and rotate the circle in the middle. This will show you what it's doing incorrectly. https://drive.google.com/open?id=1ly1o5YdeOocDNKCiNDynGXk_HA4JaC77 This was created by following this simple YouTube tutorial (which worked perfectly in 2.79b). https://youtu.be/a9nGRM6q1Ik?list=LLIHO4S6ShYCr6Gr6zWF2u4Q Email me with further questions or info at: matbrady1@gmail.com

Mat Brady commented

2020-03-20 23:21:09 +01:00

Added subscriber: @MatBrady

Ankit Meel commented

2020-03-21 08:57:19 +01:00

Added subscriber: @ankitm

Ankit Meel commented

2020-03-21 08:57:19 +01:00

The plate indeed snaps back to a wrong location, but it would still be good to rule out human error and try an updated tutorial or community website. https://www.blender.org/community/

Ankit Meel commented

2020-03-21 08:57:43 +01:00

Changed status from 'Needs Triage' to: 'Needs User Info'

Mat Brady commented

2020-03-25 03:48:44 +01:00

This bug report is a result of opening a 2.79 rig in 2.8x and discovering what broke. The same basic process behind the rig should still work because the same basic features in 2.79 are still in Blender 2.8x -

Curve Modifier
Make Vertex Parent
Transformation Constraint
Array

The tutorial is still valid, even from 2.79, since the features are still present in 2.8x.

The rig I linked above demonstrates where some bugs might be in the 2.8x version. My guess is that the Transformation Constraint hasn't made the shift to 2.8x unharmed.

I'd be willing to work with the developers to get to the bottom of why this is.

This bug report is a result of opening a 2.79 rig in 2.8x and discovering what broke. The same basic process behind the rig should still work because the same basic features in 2.79 are still in Blender 2.8x - - Curve Modifier - Make Vertex Parent - Transformation Constraint - Array The tutorial is still valid, even from 2.79, since the features are still present in 2.8x. The rig I linked above demonstrates where some bugs might be in the 2.8x version. My guess is that the Transformation Constraint hasn't made the shift to 2.8x unharmed. I'd be willing to work with the developers to get to the bottom of why this is.

Ankit Meel commented

2020-03-28 14:36:10 +01:00

Changed status from 'Needs User Info' to: 'Needs Triage'

Germano Cavalcante commented

2020-03-31 14:44:50 +02:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2020-03-31 14:44:50 +02:00

Here is the same file in blender 2.79b:
Tanks00 - recreate experiment 01 2_79b.blend

The result is the same, so it's not a regression.
But I'm not sure if the constraint should behave that way.

Here is the same file in blender 2.79b: [Tanks00 - recreate experiment 01 2_79b.blend](https://archive.blender.org/developer/F8439063/Tanks00_-_recreate_experiment_01_2_79b.blend) The result is the same, so it's not a regression. But I'm not sure if the constraint should behave that way.

Mat Brady commented

2020-04-02 09:44:19 +02:00

Germano, thanks for the confirmation.
I've also now confirmed that the Transform Constraint in 2.79 doesn't work as expected.

I've noticed that it will flip positions when the rotation gets to 180 degrees or -180 degrees.

This makes me think it might be a Euler rotation issue, but I've not had any success changing it.

Germano, thanks for the confirmation. I've also now confirmed that the Transform Constraint in 2.79 doesn't work as expected. I've noticed that it will flip positions when the rotation gets to 180 degrees or -180 degrees. This makes me think it might be a Euler rotation issue, but I've not had any success changing it.

Germano Cavalcante commented

2020-04-02 14:08:01 +02:00

I analyzed the code and in fact it is a limitation when calculating the euler.
The angle value is obtained by the object's matrix, so the code doesn't know the difference between 361º and 1º for example.

It is a similar problem to #74266
There is no simple solution. And this code is old and not often maintained.

I analyzed the code and in fact it is a limitation when calculating the euler. The angle value is obtained by the object's matrix, so the code doesn't know the difference between 361º and 1º for example. It is a similar problem to #74266 There is no simple solution. And this code is old and not often maintained.

Germano Cavalcante commented

2020-04-02 14:08:22 +02:00

Closed as duplicate of #74266

Germano Cavalcante closed this issue

2020-04-02 14:08:22 +02:00

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Extrapolate within the Transformation Constraint not working correctly #74988