Parenting object to a curve acts as if parenting to first curve point #98489

New Issue

Demeter Dzadik · 2022-05-30T11:08:34+02:00

Demeter Dzadik commented

2022-05-30 11:08:34 +02:00

Blender Version
Broken: version: 3.3.0 Alpha, branch: master, commit date: 2022-05-30 08:14, hash: fc3c589b18
Worked: Unknown

Short description of error
When parenting an object to a curve using very basic object parenting, it actually acts as if the object was parented to the first curve point, rather than the curve object itself.
So when moving the first curve point in edit mode, the object moves.

Exact steps for others to reproduce the error

Add a Bezier Curve
Parent default cube to the curve with Ctrl+P->Object
Enter edit mode in the curve
Any operations here shouldn't affect the child object (the default cube), but moving the first curve point moves the cube.
The relationship line between the cube and the curve also indicate that the cube is parented to the first curve point, rather than the curve object's origin.

curve_parenting-2022-05-30_11.02.44.mp4

**Blender Version** Broken: version: 3.3.0 Alpha, branch: master, commit date: 2022-05-30 08:14, hash: `fc3c589b18` Worked: Unknown **Short description of error** When parenting an object to a curve using very basic object parenting, it actually acts as if the object was parented to the first curve point, rather than the curve object itself. So when moving the first curve point in edit mode, the object moves. **Exact steps for others to reproduce the error** - Add a Bezier Curve - Parent default cube to the curve with Ctrl+P->Object - Enter edit mode in the curve - Any operations here shouldn't affect the child object (the default cube), but moving the first curve point moves the cube. - The relationship line between the cube and the curve also indicate that the cube is parented to the first curve point, rather than the curve object's origin. [curve_parenting-2022-05-30_11.02.44.mp4](https://archive.blender.org/developer/F13122648/curve_parenting-2022-05-30_11.02.44.mp4)

Demeter Dzadik commented

2022-05-30 11:08:34 +02:00

Added subscriber: @Mets

Philipp Oeser commented

2022-05-30 11:56:39 +02:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2022-05-30 11:56:39 +02:00

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

Philipp Oeser commented

2022-05-30 11:56:39 +02:00

It is a bit weird, but this still uses Path Animation setting from the curve (check the curve data panel):

if this option is ON it follows the path (not the first point, not the last point, this depends on the Evaluation Time)
if this is OFF, you'll get "regular" object only parenting behavior

Not really a bug, might be worth checking if this is something that is in need of some rethinking?
Makes sense? If so, would vote for not keeping this in the tracker though

It is a bit weird, but this still uses `Path Animation` setting from the curve (check the curve data panel): - if this option is ON it follows the path (not the first point, not the last point, this depends on the `Evaluation Time`) - if this is OFF, you'll get "regular" object only parenting behavior Not really a bug, might be worth checking if this is something that is in need of some rethinking? Makes sense? If so, would vote for not keeping this in the tracker though

Simon Thommes commented

2022-05-30 12:21:29 +02:00

Added subscriber: @SimonThommes

Simon Thommes commented

2022-05-30 12:21:29 +02:00

There is no good reason imo to have object parenting work differently for curves when there are such things as constraints to achieve the same thing. There is a series of other hidden functionalities baked into the curve object.

This behaviour will thankfully just go away with the new curves object type. So for the time being, I guess, as this is not a bug the report can be archived.

There is no good reason imo to have object parenting work differently for curves when there are such things as constraints to achieve the same thing. There is a series of other hidden functionalities baked into the curve object. This behaviour will thankfully just go away with the new curves object type. So for the time being, I guess, as this is not a bug the report can be archived.

Demeter Dzadik commented

2022-05-30 12:25:38 +02:00

Added subscriber: @HooglyBoogly

Demeter Dzadik commented

2022-05-30 12:25:38 +02:00

While playing around with it a bit more, I also discovered something that looks more like a bug:

Disable Path Animation
Parent object
Enable Path Animation
Child object doesn't update in real-time (missing dependency I guess)
curve_madness-2022-05-30_12.16.38.mp4

But this whole thing is such a mess that I wouldn't want anyone to waste time actually trying to fix it, as long as this is on the radar of the guys making the new Curves objects, all will be well. I also didn't even mention yet how the secret setting of the parent inverse matrix when using Ctrl+P is a massive and unnecessary pitfall.

"This is the dumbest thing."

@HooglyBoogly

This was the reaction when @SimonThommes (who originally discovered this) showed the original issue to Hans, so I'd leave it up to him if this should be closed as not-a-bug or converted/re-made as a design task on how Path Animation should work for the new Curves object type.

While playing around with it a bit more, I also discovered something that looks more like a bug: - Disable Path Animation - Parent object - Enable Path Animation - Child object doesn't update in real-time (missing dependency I guess) [curve_madness-2022-05-30_12.16.38.mp4](https://archive.blender.org/developer/F13122748/curve_madness-2022-05-30_12.16.38.mp4) But this whole thing is such a mess that I wouldn't want anyone to waste time actually trying to fix it, as long as this is on the radar of the guys making the new Curves objects, all will be well. I also didn't even mention yet how the secret setting of the parent inverse matrix when using Ctrl+P is a massive and unnecessary pitfall. > "This is the dumbest thing." > - @HooglyBoogly This was the reaction when @SimonThommes (who originally discovered this) showed the original issue to Hans, so I'd leave it up to him if this should be closed as not-a-bug or converted/re-made as a design task on how Path Animation should work for the new Curves object type.

Hans Goudey commented

2022-05-30 12:45:10 +02:00

I made a design task about simplifying this area and updating it to use the new curves type: #98494

So I think I'll close this, since that task describes how to improve the issues here on a design level.

I made a design task about simplifying this area and updating it to use the new curves type: #98494 So I think I'll close this, since that task describes how to improve the issues here on a design level.

Hans Goudey commented

2022-05-30 12:45:54 +02:00

Closed as duplicate of #98494

Hans Goudey closed this issue

2022-05-30 12:45:54 +02:00

Philipp Oeser commented

2022-05-30 13:07:41 +02:00

Changed status from 'Duplicate' to: 'Needs Developer To Reproduce'

Philipp Oeser reopened this issue

2022-05-30 13:07:41 +02:00

Philipp Oeser commented

2022-05-30 13:07:41 +02:00

In #98489#1366491, @Mets wrote:
While playing around with it a bit more, I also discovered something that looks more like a bug:

True. the following would update dependencies but not take care of correcting the parent matrix since for that the RNA callback would need to walk over objects to find all possible children I think... (but strictly speaking, this would need to be reported separately -- and then again there seems to be consensus to not spend time on this?)
P2982: T98489_snippet



diff --git a/source/blender/makesrna/intern/rna_curve.c b/source/blender/makesrna/intern/rna_curve.c
index 49b78e90024..ca87ba8b958 100644
--- a/source/blender/makesrna/intern/rna_curve.c
+++ b/source/blender/makesrna/intern/rna_curve.c
@@ -1007,7 +1007,7 @@ static void rna_def_path(BlenderRNA *UNUSED(brna), StructRNA *srna)
   prop = RNA_def_property(srna, "use_path", PROP_BOOLEAN, PROP_NONE);
   RNA_def_property_boolean_sdna(prop, NULL, "flag", CU_PATH);
   RNA_def_property_ui_text(prop, "Path", "Enable the curve to become a translation path");
-  RNA_def_property_update(prop, 0, "rna_Curve_update_data");
+  RNA_def_property_update(prop, 0, "rna_Curve_update_deps");
 
   prop = RNA_def_property(srna, "use_path_follow", PROP_BOOLEAN, PROP_NONE);
   RNA_def_property_boolean_sdna(prop, NULL, "flag", CU_FOLLOW);

> In #98489#1366491, @Mets wrote: > While playing around with it a bit more, I also discovered something that looks more like a bug: True. the following would update dependencies but not take care of correcting the parent matrix since for that the RNA callback would need to walk over objects to find all possible children I think... (but strictly speaking, this would need to be reported separately -- and then again there seems to be consensus to not spend time on this?) [P2982: T98489_snippet](https://archive.blender.org/developer/P2982.txt) ``` diff --git a/source/blender/makesrna/intern/rna_curve.c b/source/blender/makesrna/intern/rna_curve.c index 49b78e90024..ca87ba8b958 100644 --- a/source/blender/makesrna/intern/rna_curve.c +++ b/source/blender/makesrna/intern/rna_curve.c @@ -1007,7 +1007,7 @@ static void rna_def_path(BlenderRNA *UNUSED(brna), StructRNA *srna) prop = RNA_def_property(srna, "use_path", PROP_BOOLEAN, PROP_NONE); RNA_def_property_boolean_sdna(prop, NULL, "flag", CU_PATH); RNA_def_property_ui_text(prop, "Path", "Enable the curve to become a translation path"); - RNA_def_property_update(prop, 0, "rna_Curve_update_data"); + RNA_def_property_update(prop, 0, "rna_Curve_update_deps"); prop = RNA_def_property(srna, "use_path_follow", PROP_BOOLEAN, PROP_NONE); RNA_def_property_boolean_sdna(prop, NULL, "flag", CU_FOLLOW); ```

Philipp Oeser commented

2022-05-30 13:08:44 +02:00

Oops, was too slow

Philipp Oeser commented

2022-05-30 13:08:54 +02:00

Closed as duplicate of #98494

Philipp Oeser closed this issue

2022-05-30 13:08:54 +02:00

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Parenting object to a curve acts as if parenting to first curve point #98489