Playback set start/end operators can set rendering range fields to negative frames #81380

New Issue

Tomasz Kaye · 2020-10-02T13:52:37+02:00

Tomasz Kaye commented

2020-10-02 13:52:37 +02:00

System Information
Operating system: Darwin-19.3.0-x86_64-i386-64bit 64 Bits
Graphics card: AMD Radeon Pro 580 OpenGL Engine ATI Technologies Inc. 4.1 ATI-3.5.5

Blender Version
Broken: version: 2.91.0 Alpha, branch: master, commit date: 2020-09-26 20:04, hash: 8c81b3fb8b

Short description of error

Original report: The playback/rendering range fields (top right of Timeline view) can't be set to negative frames directly, this should be possible.

This is not a bug

Original report: This range can be set to begin on a negative frame by moving the playhead to a negative frame and then using Timeline > Playback > 'Set Start Frame' button,

This is a bug

Exact steps for others to reproduce the error

Enable "Allow Negative Frames" in preferences
Try to change the Start field to a number below 0 (it clamps to 0)

**System Information** Operating system: Darwin-19.3.0-x86_64-i386-64bit 64 Bits Graphics card: AMD Radeon Pro 580 OpenGL Engine ATI Technologies Inc. 4.1 ATI-3.5.5 **Blender Version** Broken: version: 2.91.0 Alpha, branch: master, commit date: 2020-09-26 20:04, hash: `8c81b3fb8b` **Short description of error** > Original report: The playback/rendering range fields (top right of Timeline view) can't be set to negative frames directly, this should be possible. This is not a bug ![Screenshot 2020-10-02 at 13.44.30.png](https://archive.blender.org/developer/F8946888/Screenshot_2020-10-02_at_13.44.30.png) > Original report: This range *can* be set to begin on a negative frame by moving the playhead to a negative frame and then using Timeline > Playback > 'Set Start Frame' button, This is a bug ![Screenshot 2020-10-02 at 13.47.09.png](https://archive.blender.org/developer/F8946896/Screenshot_2020-10-02_at_13.47.09.png) **Exact steps for others to reproduce the error** * Enable "Allow Negative Frames" in preferences ![Screenshot 2020-10-02 at 13.50.44.png](https://archive.blender.org/developer/F8946901/Screenshot_2020-10-02_at_13.50.44.png) * Try to change the Start field to a number below 0 (it clamps to 0)

Tomasz Kaye commented

2020-10-02 13:52:37 +02:00

Added subscriber: @info-27

Philipp Oeser commented

2020-10-05 15:14:21 +02:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2020-10-05 15:14:21 +02:00

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

Philipp Oeser self-assigned this 2020-10-05 15:14:21 +02:00

Philipp Oeser commented

2020-10-05 15:14:21 +02:00

Can confirm some sort of inconsistency.

I assume though that not allowing negative frames for scene render is actually the right thing to do, see the comment in rna_Scene_start_frame_set:

/* MINFRAME ... since some output formats can't take negative frames */

On the other hand, there is the Allow Negative Frames option, introduced in 21a2350248.
This commit claims:

This setting only applies when setting the current frame by scrubbing the time cursor in a timeline view, or by typing a value into the current frame number field.

And the documentation https://docs.blender.org/manual/en/dev/editors/preferences/animation.html#timeline says

Playback and animations can occur during negative frame ranges.

I am reading this as "setting current frame to a negative value should be allowed, setting the preview range to a negative value should be allowed, however setting the scene render startframe/endframe should never be allowed.
But as we can see there are a couple of places where we can end up with negative framenumbers for scene render.
Therefore, this looks like a bug.
(The whole thing might also be considered designed schizophrenia :), but for now lets make sure we dont end up with negative in scene render.)

#42151 (Can't set negative Frame start)
#70473 (It is not possible to start at negative frame)
#52872 (Toggle "Playback Negative Frames" not working)

Can confirm some sort of inconsistency. I assume though that not allowing negative frames for scene render is actually the right thing to do, see the comment in `rna_Scene_start_frame_set`: ``` /* MINFRAME ... since some output formats can't take negative frames */ ``` On the other hand, there is the `Allow Negative Frames` option, introduced in 21a2350248. This commit claims: > This setting only applies when setting the current frame by scrubbing the time cursor in a timeline view, or by typing a value into the current frame number field. And the documentation https://docs.blender.org/manual/en/dev/editors/preferences/animation.html#timeline says > Playback and animations can occur during negative frame ranges. I am reading this as "setting current frame to a negative value should be allowed, setting the preview range to a negative value should be allowed, however setting the scene render startframe/endframe should **never** be allowed. But as we can see there are a couple of places where we can end up with negative framenumbers for scene render. Therefore, this looks like a bug. (The whole thing might also be considered *designed schizophrenia* :), but for now lets make sure we dont end up with negative in scene render.) Related: - #42151 (Can't set negative Frame start) - #70473 (It is not possible to start at negative frame) - #52872 (Toggle "Playback Negative Frames" not working)

Philipp Oeser changed title from ~~Playback/rendering range fields can't be set to negative frames~~ to Playback set start/end operators can set rendering range fields to negative frames

2020-10-05 15:38:40 +02:00

Philipp Oeser commented

2020-10-05 15:39:14 +02:00

I have change the task description to reflect what is considered a bug and what isnt.

blender-admin commented

2020-10-05 15:40:37 +02:00

This issue was referenced by ca38bce46a

This issue was referenced by ca38bce46aa292654451fa34fc33b88fc5ca72f0

Philipp Oeser commented

2020-10-05 18:46:48 +02:00

Changed status from 'Confirmed' to: 'Resolved'

Philipp Oeser closed this issue

2020-10-05 18:46:48 +02:00

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Playback set start/end operators can set rendering range fields to negative frames #81380