Moving python-made channels freezes Blender #81628

New Issue

RedMser · 2020-10-11T16:36:57+02:00

RedMser commented

2020-10-11 16:36:57 +02:00

System Information
Operating system: Windows-10-10.0.18362-SP0 64 Bits
Operating system: Linux-4.15.0-45-generic-x86_64-with-debian-buster-sid 64 Bits
Graphics card: GeForce RTX 2080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 456.55

Blender Version
Broken: version: 2.91.0 Alpha, branch: master, commit date: 2020-10-09 21:39, hash: 7ab8d7c939
Broken in Blender 2.83 and 2.79 as well, so it maybe never worked before?

Short description of error
Moving a channel of an animated curve created with Python gets Blender stuck in an infinite loop.

Exact steps for others to reproduce the error

Create a NURBS curve which has two animated vertices
- I have slightly modified the AnimAll addon for this, see my changes here: P1694: AnimAll changes

@@ -264,27 +264,27 @@ class ANIM_OT_insert_keyframe_animall(Operator):
                                     or CV.select_left_handle
                                     or CV.select_right_handle):
                                 if animall_properties.key_points:
-                                    insert_key(CV, 'co', group="Spline %s CV %s" % (s_i, v_i))
-                                    insert_key(CV, 'handle_left', group="Spline %s CV %s" % (s_i, v_i))
-                                    insert_key(CV, 'handle_right', group="Spline %s CV %s" % (s_i, v_i))
+                                    insert_key(CV, 'co', group="S%s V%s" % (s_i, v_i))
+                                    insert_key(CV, 'handle_left', group="S%s V%s" % (s_i, v_i))
+                                    insert_key(CV, 'handle_right', group="S%s V%s" % (s_i, v_i))
 
                                 if animall_properties.key_radius:
-                                    insert_key(CV, 'radius', group="Spline %s CV %s" % (s_i, v_i))
+                                    insert_key(CV, 'radius', group="S%s V%s" % (s_i, v_i))
 
                                 if animall_properties.key_tilt:
-                                    insert_key(CV, 'tilt', group="Spline %s CV %s" % (s_i, v_i))
+                                    insert_key(CV, 'tilt', group="S%s V%s" % (s_i, v_i))
 
                     elif spline.type in ('POLY', 'NURBS'):
                         for v_i, CV in enumerate(spline.points):
                             if not animall_properties.key_selected or CV.select:
                                 if animall_properties.key_points:
-                                    insert_key(CV, 'co', group="Spline %s CV %s" % (s_i, v_i))
+                                    insert_key(CV, 'co', group="S%s V%s" % (s_i, v_i))
 
                                 if animall_properties.key_radius:
-                                    insert_key(CV, 'radius', group="Spline %s CV %s" % (s_i, v_i))
+                                    insert_key(CV, 'radius', group="S%s V%s" % (s_i, v_i))
 
                                 if animall_properties.key_tilt:
-                                    insert_key(CV, 'tilt', group="Spline %s CV %s" % (s_i, v_i))
+                                    insert_key(CV, 'tilt', group="S%s V%s" % (s_i, v_i))
 
         bpy.ops.object.mode_set(mode='OBJECT')

Simple file for easy reproduction of this step: anim-move-curve-channel-crash.blend
In the Dopesheet Editor, click on Channel -> Move -> Up (or Down)
Blender gets frozen until you manually kill the process

Note that without my changes to the addon, this does not happen.
See this file for comparison - same steps as above, but using the default AnimAll addon, no crash here: anim-move-curve-channel-no-crash.blend
So it's probably related to the names of the keyframe groups?

To help with debugging, Blender gets stuck forever inside rearrange_action_channels -> join_groups_action_temp -> for (fcu = agrp->channels.first; fcu; fcu = fcu->next) in file anim_channels_edit.c

**System Information** Operating system: Windows-10-10.0.18362-SP0 64 Bits Operating system: Linux-4.15.0-45-generic-x86_64-with-debian-buster-sid 64 Bits Graphics card: GeForce RTX 2080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 456.55 **Blender Version** Broken: version: 2.91.0 Alpha, branch: master, commit date: 2020-10-09 21:39, hash: `7ab8d7c939` Broken in Blender 2.83 and 2.79 as well, so it maybe never worked before? **Short description of error** Moving a channel of an animated curve created with Python gets Blender stuck in an infinite loop. **Exact steps for others to reproduce the error** - Create a NURBS curve which has two animated vertices - I have slightly modified the AnimAll addon for this, see my changes here: [P1694: AnimAll changes](https://archive.blender.org/developer/P1694.txt) ```diff @@ -264,27 +264,27 @@ class ANIM_OT_insert_keyframe_animall(Operator): or CV.select_left_handle or CV.select_right_handle): if animall_properties.key_points: - insert_key(CV, 'co', group="Spline %s CV %s" % (s_i, v_i)) - insert_key(CV, 'handle_left', group="Spline %s CV %s" % (s_i, v_i)) - insert_key(CV, 'handle_right', group="Spline %s CV %s" % (s_i, v_i)) + insert_key(CV, 'co', group="S%s V%s" % (s_i, v_i)) + insert_key(CV, 'handle_left', group="S%s V%s" % (s_i, v_i)) + insert_key(CV, 'handle_right', group="S%s V%s" % (s_i, v_i)) if animall_properties.key_radius: - insert_key(CV, 'radius', group="Spline %s CV %s" % (s_i, v_i)) + insert_key(CV, 'radius', group="S%s V%s" % (s_i, v_i)) if animall_properties.key_tilt: - insert_key(CV, 'tilt', group="Spline %s CV %s" % (s_i, v_i)) + insert_key(CV, 'tilt', group="S%s V%s" % (s_i, v_i)) elif spline.type in ('POLY', 'NURBS'): for v_i, CV in enumerate(spline.points): if not animall_properties.key_selected or CV.select: if animall_properties.key_points: - insert_key(CV, 'co', group="Spline %s CV %s" % (s_i, v_i)) + insert_key(CV, 'co', group="S%s V%s" % (s_i, v_i)) if animall_properties.key_radius: - insert_key(CV, 'radius', group="Spline %s CV %s" % (s_i, v_i)) + insert_key(CV, 'radius', group="S%s V%s" % (s_i, v_i)) if animall_properties.key_tilt: - insert_key(CV, 'tilt', group="Spline %s CV %s" % (s_i, v_i)) + insert_key(CV, 'tilt', group="S%s V%s" % (s_i, v_i)) bpy.ops.object.mode_set(mode='OBJECT') ``` - Simple file for easy reproduction of this step: [anim-move-curve-channel-crash.blend](https://archive.blender.org/developer/F8979284/anim-move-curve-channel-crash.blend) - In the Dopesheet Editor, click on Channel -> Move -> Up (or Down) - Blender gets frozen until you manually kill the process Note that without my changes to the addon, this does not happen. See this file for comparison - same steps as above, but using the default AnimAll addon, no crash here: [anim-move-curve-channel-no-crash.blend](https://archive.blender.org/developer/F8979300/anim-move-curve-channel-no-crash.blend) So it's probably related to the names of the keyframe groups? To help with debugging, Blender gets stuck forever inside `rearrange_action_channels` -> `join_groups_action_temp` -> `for (fcu = agrp->channels.first; fcu; fcu = fcu->next)` in file `anim_channels_edit.c`

RedMser commented

2020-10-11 16:36:57 +02:00

Added subscriber: @RedMser

Philipp Oeser commented

2020-10-12 10:44:43 +02:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2020-10-12 10:44:43 +02:00

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

Philipp Oeser self-assigned this 2020-10-12 10:44:43 +02:00

Philipp Oeser commented

2020-10-12 10:44:43 +02:00

Can confirm, will check on this.

Philipp Oeser commented

2020-10-12 15:36:57 +02:00

First note: for some reason the bActionGroups are not in the right order in the failing file.
I think what should always be the case is that the last ActionGroup's last FCurve should not have fcu->next set (it should be NULL).
The preceeding ActionGroups last FCurve fcu->next should point to something valid (probably the first FCurve in the next bActionGroup)

In the borked case of this modified Addon (or just the file that results from it), the first ActionGroup's last FCurve fcu->next is already NULL.

This confuses code in split_groups_action_temp, it then thinks there are channels outside of groups, puts them in a #TempGroup and things go downhill from here.

Needs a bit more investigation if this a possible failure in the Python API or if this fails elsewhere. Stay tuned.

First note: for some reason the `bActionGroup`s are not in the right order in the failing file. I *think* what should always be the case is that the **last** ActionGroup's last FCurve should not have `fcu->next` set (it should be NULL). The preceeding ActionGroups last FCurve `fcu->next` should point to something valid (probably the first FCurve in the next `bActionGroup`) In the borked case of this modified Addon (or just the file that results from it), the **first** ActionGroup's last FCurve `fcu->next` is already NULL. This confuses code in `split_groups_action_temp`, it then thinks there are channels outside of groups, puts them in a `#TempGroup` and things go downhill from here. Needs a bit more investigation if this a possible failure in the Python API or if this fails elsewhere. Stay tuned.

Sybren A. Stüvel commented

2020-10-13 18:30:51 +02:00

Added subscriber: @dr.sybren

Sybren A. Stüvel commented

2020-10-13 18:30:51 +02:00

@lichtwerk do you have a simple way of reproducing the issue that doesn't rely on modifying some add-on?

Philipp Oeser commented

2020-10-16 14:59:12 +02:00

@dr.sybren: I am off today, but this is on my list. I have only reproduced using the method shown here, but I assume this can be reproduced in a simpler way, too.

Philipp Oeser removed their assignment 2020-11-02 16:37:55 +01:00

Philipp Oeser commented

2020-11-02 16:37:55 +01:00

Will step down to not block others

Sybren A. Stüvel commented

2020-11-02 16:42:26 +01:00

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

Sybren A. Stüvel commented

2020-11-02 16:42:26 +01:00

Thanks for the report. Unfortunately the scenario described is too time consuming for us to track down, we require the bug reporter to narrow down the problem.

Normally .blend files can be simplified by removing most objects and disabling settings, until the problem reveals itself more clearly.

In this case, please make it possible to reproduce the issue with just a bit of Python code, instead of asking us to change the code of an add-on.

Thanks for the report. Unfortunately the scenario described is too time consuming for us to track down, we require the bug reporter to narrow down the problem. Normally .blend files can be simplified by removing most objects and disabling settings, until the problem reveals itself more clearly. In this case, please make it possible to reproduce the issue with just a bit of Python code, instead of asking us to change the code of an add-on.

Sybren A. Stüvel commented

2020-11-27 13:03:32 +01:00

No activity for more than a week. As per the tracker policy we assume the issue is gone and can be closed.

Thanks again for the report. If the problem persists please open a new report with the required information.

No activity for more than a week. As per the tracker policy we assume the issue is gone and can be closed. Thanks again for the report. If the problem persists please open a new report with the required information.

Damien Picard commented

2020-11-29 02:44:00 +01:00

Added subscriber: @pioverfour

Damien Picard commented

2020-11-29 02:44:00 +01:00

I don’t believe modifying AnimAll is necessary. I could reproduce the crash with the following script:

import bpy

# Setup
curve = bpy.data.curves.new("curve", "CURVE")
curve_obj = bpy.data.objects.new("curve", curve)

spline = curve.splines.new("NURBS")
spline.points.add(4)

bpy.context.collection.objects.link(curve_obj)
bpy.context.view_layer.objects.active = curve_obj
curve_obj.select_set(True)


# Insert keyframes
curve.splines- [x].points- [x].keyframe_insert("co", group="Spline 0 CV 3")
curve.splines- [x].points- [x].keyframe_insert("co", group="Spline 0 CV 0")

bpy.ops.object.mode_set(mode='EDIT')
bpy.ops.object.mode_set(mode='OBJECT')
bpy.ops.object.mode_set(mode='EDIT')

The double mode toggling at the end is necessary for the crash to happen. This is done in AnimAll because some types of keyframes can only be inserted in a specific mode.
The steps to reproduce are thus:

Run this script
Open dope sheet
Select a channel group
Channel -> Move -> Up or press PageUp

I don’t believe modifying AnimAll is necessary. I could reproduce the crash with the following script: ```lang=python import bpy # Setup curve = bpy.data.curves.new("curve", "CURVE") curve_obj = bpy.data.objects.new("curve", curve) spline = curve.splines.new("NURBS") spline.points.add(4) bpy.context.collection.objects.link(curve_obj) bpy.context.view_layer.objects.active = curve_obj curve_obj.select_set(True) # Insert keyframes curve.splines- [x].points- [x].keyframe_insert("co", group="Spline 0 CV 3") curve.splines- [x].points- [x].keyframe_insert("co", group="Spline 0 CV 0") bpy.ops.object.mode_set(mode='EDIT') bpy.ops.object.mode_set(mode='OBJECT') bpy.ops.object.mode_set(mode='EDIT') ``` The double mode toggling at the end is necessary for the crash to happen. This is done in AnimAll because some types of keyframes can only be inserted in a specific mode. The steps to reproduce are thus: * Run this script * Open dope sheet * Select a channel group * Channel -> Move -> Up or press `PageUp`

Philipp Oeser commented

2020-11-29 08:00:01 +01:00

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