Geometry: add utility to check for bad geometry element index dependence #113030

Jacques Lucke · 2023-09-28T20:28:21+02:00

Jacques Lucke commented

2023-09-28 20:28:21 +02:00

Sometimes .blend files have compatibility issues between Blender versions, because .blend files depended on the specific order of geometry elements generated by some nodes/modifiers (#112746, #113018). While we make guarantees about the order in some places, that is relatively rare, because it makes future improvements much harder. The functionality in this patch makes it easier for users to notice when they depend on things that are not expected to be stable between Blender builds.

This is achieved by adding a new global flag which indicates whether some algorithms should randomize their output. The functionality can be toggled on or off by searching for Set Geometry Randomization. If there are no differences (or acceptable minor ones) when the flag is on or off, one can be reasonably sure that one does not on unspecified behavior (can't be 100% sure though, because randomization might be missing in some places). If there are big differences, one should consider fixing the file before it comes to an actual breakage in the next Blender version.

Currently, the setting is only available when Developer Extras is turned on, because the setting is in no menu.

With this patch, if we get bug reports with compatibility issues caused by depending on indices, one of the following three cases should always apply:

We actually accidentally broke something, which requires a fix commit.
Turning on geometry randomization shows that the .blend file depends on things it shouldn't depend on. In this case the user has to fix the file.
We are missing geometry randomization somewhere, which requires a fix commit.

Sometimes .blend files have compatibility issues between Blender versions, because .blend files depended on the specific order of geometry elements generated by some nodes/modifiers (#112746, #113018). While we make guarantees about the order in some places, that is relatively rare, because it makes future improvements much harder. The functionality in this patch makes it easier for users to notice when they depend on things that are not expected to be stable between Blender builds. This is achieved by adding a new global flag which indicates whether some algorithms should randomize their output. The functionality can be toggled on or off by searching for `Set Geometry Randomization`. If there are no differences (or acceptable minor ones) when the flag is on or off, one can be reasonably sure that one does not on unspecified behavior (can't be 100% sure though, because randomization might be missing in some places). If there are big differences, one should consider fixing the file before it comes to an actual breakage in the next Blender version. Currently, the setting is only available when `Developer Extras` is turned on, because the setting is in no menu. With this patch, if we get bug reports with compatibility issues caused by depending on indices, one of the following three cases should always apply: * We actually accidentally broke something, which requires a fix commit. * Turning on geometry randomization shows that the .blend file depends on things it shouldn't depend on. In this case the user has to fix the file. * We are missing geometry randomization somewhere, which requires a fix commit. ![image](/attachments/d8f48aa5-39ca-4286-96fa-6f5905ba9a3f)

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19 KiB

2023-09-28 23-07-14.mp4

653 KiB

Jacques Lucke added 9 commits 2023-09-28 20:28:36 +02:00

1365355eec add global flag

4f6a9debd8 randomize vertex order

5c974804bd randomize edge order

fd7acf047b randomize face order

6325bc5e1b randomize point order

515c1b710f randomize curve order

d932392c6d cleanup

a45f3ac151 progress

b08faff309 cleanup

Jacques Lucke added 1 commit 2023-09-28 21:14:17 +02:00

512e66cf51 fix

Jacques Lucke added 4 commits 2023-09-28 22:43:35 +02:00

6939e6d233 move to geometry module

62a54db6d3 add randomization in more places

22001aa216 add more randomization to various nodes

88a9e46210 improve naming

Jacques Lucke added 1 commit 2023-09-28 22:47:58 +02:00

911b741d04 add comment

Jacques Lucke added 2 commits 2023-09-28 23:13:27 +02:00

c398149548 add randomization to some modifiers

2f6e528294 add comment

Jacques Lucke requested review from Hans Goudey 2023-09-28 23:13:43 +02:00

Jacques Lucke added 1 commit 2023-09-28 23:14:55 +02:00

buildbot/vexp-code-patch-coordinator Build done. Details

1322ce0257 cleanup

Jacques Lucke commented

2023-09-28 23:15:35 +02:00

@blender-bot build

Hans Goudey approved these changes 2023-09-29 17:33:16 +02:00

Hans Goudey left a comment

It would be nice to put this in a menu, but I'm not sure where, so I think it's okay for now.

source/blender/editors/geometry/geometry_randomization.cc Outdated

						
				@ -0,0 +52,4 @@

				                  "Value",

				                  "Randomize the order of geometry elements (e.g. vertices or edges) after some "

				                  "operations where there are no guarantees about the order. This avoids "

				                  "accidentally depending on something that is likely to change in the future");

Hans Goudey commented

2023-09-29 17:22:19 +02:00

is likely to -> may?

`is likely to` -> `may`?

JacquesLucke marked this conversation as resolved

source/blender/geometry/GEO_randomize.hh

						
				@ -0,0 +12,4 @@

				namespace blender::geometry {

				bool use_debug_randomization();

Hans Goudey commented

2023-09-29 17:23:57 +02:00

I guess this is mostly an aesthetic thing, but I'd like to see see these functions have a debug_ prefix, and do the use_debug_randomization themselves. That way the calling code can be nicer without the if statements.

I guess this is mostly an aesthetic thing, but I'd like to see see these functions have a `debug_` prefix, and do the `use_debug_randomization` themselves. That way the calling code can be nicer without the if statements.

JacquesLucke marked this conversation as resolved

Jacques Lucke added 3 commits 2023-09-29 21:40:46 +02:00

ead4b72d06 Merge branch 'blender-v4.0-release' into index-dependence-check

078663a736 improve comment

5c50d9638f avoid condition at the call side

Jacques Lucke merged commit cc7da09c1b into blender-v4.0-release

2023-09-29 21:44:45 +02:00

Jacques Lucke referenced this issue from a commit

2023-09-29 21:44:45 +02:00

Geometry: add utility to check for bad geometry element index dependence

Jacques Lucke deleted branch index-dependence-check

2023-09-29 21:44:46 +02:00

Dalai Felinto commented

2023-10-02 10:40:42 +02:00

The Developers Extra > Experimental menu has some "permanent" options in the Debugging Panel. Maybe expose this there?

Jacques Lucke commented

2023-10-02 11:52:52 +02:00

Doesn't sound too bad. The main difference to the other options is that this is not stored in the user preferences. That's because we don't really want people to have it enabled all the time, since it makes things slower.

Joseph Eagar referenced this issue from a commit

2023-10-07 21:46:16 +02:00

Geometry: add utility to check for bad geometry element index dependence

Joseph Eagar referenced this issue from a commit

2023-10-07 21:46:17 +02:00

Geometry: add utility to check for bad geometry element index dependence

Colin Basnett referenced this issue from a commit

2023-10-08 23:38:52 +02:00

Geometry: add utility to check for bad geometry element index dependence

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