Pose Library: temporarily load Action asset #86183

New Issue

Sybren A. Stüvel · 2021-03-02T10:22:27+01:00

Sybren A. Stüvel commented

2021-03-02 10:22:27 +01:00

The Pose Library system is going to perform the following steps:

Given the active asset in the Asset Browser, load the associated datablock as non-main temp datablock.
Apply the pose in that datablock by evaluating it (#86159 and #86160).
Free the datablock.

This task is about implementing steps 1. and 3.

The idea behind the current pose library project is that its behaviour is seen from Blender's perspective as "custom use" of an asset; this means it's simply implemented in Python in a way that add-ons could also use. For now it's probably the simplest to have two functions exposed in RNA for respectively steps 1 and 3, so that Python code can use it.

By temporarily loading the Action datablock, pollution of the main database is prevented. At some point it'll be nice to have some form of caching, which is what #86184 is about.

The Pose Library system is going to perform the following steps: 1. Given the active asset in the Asset Browser, load the associated datablock as non-main temp datablock. 2. Apply the pose in that datablock by evaluating it (#86159 and #86160). 3. Free the datablock. This task is about implementing steps 1. and 3. The idea behind the current pose library project is that its behaviour is seen from Blender's perspective as "custom use" of an asset; this means it's simply implemented in Python in a way that add-ons could also use. For now it's probably the simplest to have two functions exposed in RNA for respectively steps 1 and 3, so that Python code can use it. By temporarily loading the Action datablock, pollution of the main database is prevented. At some point it'll be nice to have some form of caching, which is what #86184 is about.

Campbell Barton was assigned by Sybren A. Stüvel

2021-03-02 10:22:27 +01:00

Sybren A. Stüvel commented

2021-03-02 10:22:27 +01:00

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

Sybren A. Stüvel commented

2021-03-02 10:22:27 +01:00

Added subscriber: @dr.sybren

Bastien Montagne commented

2021-03-02 11:30:19 +01:00

Added subscriber: @mont29

Bastien Montagne commented

2021-03-02 11:30:19 +01:00

#Core module should have been tagged here, this falls directly under its umbrella.

While I am not especially thrilled to add even more complexity to ID management, I can see how this might be useful... But it should be fully decoupled/isolated from data in Main data-base. Would suggest the following requirements:

Loaded IDs must be put in their own temp Main container.
Loaded IDs must be properly poisoned (with a new tag?) to prevent them from ever being linked in any way by IDs from actual Main data-base.
- This implies adding checks in several places for that poison tag (RNA ID pointer assignment, ID template?, ...).
- Not sure how this plays with your point 2. above? Do you intend to use Depsgraph for this evaluation, or some fully independent code?
Loaded IDs must not use session_uuid (we do not want them to increase this global counter).
As suggested by @ideasman42, this should be exposed as a context manager in Python API (similar to the one we already have to parse and link IDs from .blend libraries).

*#Core module should have been tagged here, this falls directly under its umbrella.* While I am not especially thrilled to add even more complexity to ID management, I can see how this might be useful... But it should be fully decoupled/isolated from data in Main data-base. Would suggest the following requirements: - Loaded IDs must be put in their own temp `Main` container. - Loaded IDs must be properly poisoned (with a new tag?) to prevent them from ever being linked in any way by IDs from actual Main data-base. - This implies adding checks in several places for that poison tag (RNA ID pointer assignment, ID template?, ...). - *Not sure how this plays with your point 2. above? Do you intend to use Depsgraph for this evaluation, or some fully independent code?* - Loaded IDs must not use `session_uuid` *(we do not want them to increase this global counter)*. - As suggested by @ideasman42, this should be exposed as a context manager in Python API (similar to the one we already have to parse and link IDs from .blend libraries).

Sybren A. Stüvel commented

2021-03-02 12:24:48 +01:00

Core module should have been tagged here, this falls directly under its umbrella.

You're right, thanks for doing so.

Not sure how this plays with your point 2. above? Do you intend to use Depsgraph for this evaluation, or some fully independent code?

I intend to use the animation system FCurve evaluation functions for this, and not the depsgraph:

void BKE_pose_apply_action(struct Object *ob,
                           struct bAction *action,
                           struct AnimationEvalContext *anim_eval_context)
{
  bPose *pose = ob->pose;

  GSet *selected_bone_names = NULL;
  const bool limit_to_selected_bones = pose_apply_find_selected_bones(pose, &selected_bone_names);

  if (limit_to_selected_bones) {
    pose_apply_disable_fcurves_for_unselected_bones(action, selected_bone_names);
  }

  /* Apply the Action. */
  PointerRNA pose_owner_ptr;
  RNA_id_pointer_create(&ob->id, &pose_owner_ptr);
  animsys_evaluate_action(&pose_owner_ptr, action, &anim_eval_context, false);

  if (limit_to_selected_bones) {
    pose_apply_restore_fcurves(action);
  }

  BLI_gset_free(selected_bone_names, NULL);
}

this should be exposed as a context manager in Python API

I agree, although it probably shouldn't be the only available API for this. It should be possible to do something like this in a modal operator:

temp-load an Action datablock
apply the pose with various blend parameters, based on user input
repeat the previous step until the user confirms or cancels
unload the temp datablock

Of course I agree with everything else you wrote that I didn't quote here.

> Core module should have been tagged here, this falls directly under its umbrella. You're right, thanks for doing so. > Not sure how this plays with your point 2. above? Do you intend to use Depsgraph for this evaluation, or some fully independent code? I intend to use the animation system FCurve evaluation functions for this, and not the depsgraph: ``` void BKE_pose_apply_action(struct Object *ob, struct bAction *action, struct AnimationEvalContext *anim_eval_context) { bPose *pose = ob->pose; GSet *selected_bone_names = NULL; const bool limit_to_selected_bones = pose_apply_find_selected_bones(pose, &selected_bone_names); if (limit_to_selected_bones) { pose_apply_disable_fcurves_for_unselected_bones(action, selected_bone_names); } /* Apply the Action. */ PointerRNA pose_owner_ptr; RNA_id_pointer_create(&ob->id, &pose_owner_ptr); animsys_evaluate_action(&pose_owner_ptr, action, &anim_eval_context, false); if (limit_to_selected_bones) { pose_apply_restore_fcurves(action); } BLI_gset_free(selected_bone_names, NULL); } ``` > this should be exposed as a context manager in Python API I agree, although it probably shouldn't be the only available API for this. It should be possible to do something like this in a modal operator: - temp-load an Action datablock - apply the pose with various blend parameters, based on user input - repeat the previous step until the user confirms or cancels - unload the temp datablock Of course I agree with everything else you wrote that I didn't quote here.

Bastien Montagne commented

2021-03-02 14:19:33 +01:00

In #86183#1122464, @dr.sybren wrote:

Not sure how this plays with your point 2. above? Do you intend to use Depsgraph for this evaluation, or some fully independent code?

I intend to use the animation system FCurve evaluation functions for this, and not the depsgraph:
void BKE_pose_apply_action(struct Object *ob,
                           struct bAction *action,
                           struct AnimationEvalContext *anim_eval_context)

OK then this should play nicely with action being fully outside of current Main data-base.

this should be exposed as a context manager in Python API

I agree, although it probably shouldn't be the only available API for this. It should be possible to do something like this in a modal operator:

temp-load an Action datablock

apply the pose with various blend parameters, based on user input

repeat the previous step until the user confirms or cancels

unload the temp datablock

This should be doable with a context manager too? I mean, one can still open() a file, do whatever with the returned value, and close it themselves right?

I would keep it hidden/advanced way to deal with it though (so just having to explicitly call __enter__() and __exit__() functions).

One could even argue that the underlying code should be the one to be smart here, caching the libs, so that re-creating the context would be almost for free?

> In #86183#1122464, @dr.sybren wrote: >> Not sure how this plays with your point 2. above? Do you intend to use Depsgraph for this evaluation, or some fully independent code? > I intend to use the animation system FCurve evaluation functions for this, and not the depsgraph: > > ``` > void BKE_pose_apply_action(struct Object *ob, > struct bAction *action, > struct AnimationEvalContext *anim_eval_context) OK then this should play nicely with action being fully outside of current Main data-base. >> this should be exposed as a context manager in Python API > I agree, although it probably shouldn't be the only available API for this. It should be possible to do something like this in a modal operator: > - temp-load an Action datablock > - apply the pose with various blend parameters, based on user input > - repeat the previous step until the user confirms or cancels > - unload the temp datablock This should be doable with a context manager too? I mean, one can still `open()` a file, do whatever with the returned value, and close it themselves right? I would keep it hidden/advanced way to deal with it though (so just having to explicitly call `__enter__()` and `__exit__()` functions). One could even argue that the underlying code should be the one to be smart here, caching the libs, so that re-creating the context would be almost for free?

Bastien Montagne commented

2021-03-02 14:21:09 +01:00

On a side note, I don't think we should lock ourselves to Actions for PoseLib here. Can imagine similar needs/processes for e.g. pre-visualizing a texture in a shader, or a whole shader on an object, etc.?

Sybren A. Stüvel commented

2021-03-02 15:24:03 +01:00

In #86183#1122541, @mont29 wrote:
This should be doable with a context manager too? I mean, one can still open() a file, do whatever with the returned value, and close it themselves right?

Yes, but that's because open() returns an object that can be used both as a file and as a context manager. This isn't a property of context managers in general.

I would keep it hidden/advanced way to deal with it though (so just having to explicitly call __enter__() and __exit__() functions).

I'm afraid that that'll produce some nasty mistakes, as I don't expect people to understand which parameters exactly to pass to __exit()__ under which conditions. That could be solved with proper documentation & examples, though.

One could even argue that the underlying code should be the one to be smart here, caching the libs, so that re-creating the context would be almost for free?

For sure, that's what I wrote #86184 (Asset System: cache temp-loaded datablocks) for ;-)

> In #86183#1122541, @mont29 wrote: > This should be doable with a context manager too? I mean, one can still `open()` a file, do whatever with the returned value, and close it themselves right? Yes, but that's because `open()` returns an object that can be used both as a file and as a context manager. This isn't a property of context managers in general. > I would keep it hidden/advanced way to deal with it though (so just having to explicitly call `__enter__()` and `__exit__()` functions). I'm afraid that that'll produce some nasty mistakes, as I don't expect people to understand which parameters exactly to pass to `__exit()__` under which conditions. That could be solved with proper documentation & examples, though. > One could even argue that the underlying code should be the one to be smart here, caching the libs, so that re-creating the context would be almost for free? For sure, that's what I wrote #86184 (Asset System: cache temp-loaded datablocks) for ;-)

Sybren A. Stüvel commented

2021-03-19 14:41:36 +01:00

With D10736: BLO: Functions for temporarily loading a single datablock having landed in master, this task is complete.

With [D10736: BLO: Functions for temporarily loading a single datablock](https://archive.blender.org/developer/D10736) having landed in master, this task is complete.

Sybren A. Stüvel commented

2021-03-19 14:41:59 +01:00

Changed status from 'Confirmed' to: 'Resolved'

Sybren A. Stüvel closed this issue

2021-03-19 14:41:59 +01:00

Brecht Van Lommel added the

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Pose Library: temporarily load Action asset #86183