Add useful functions to FilterEdit in AnimationBlendTreeEditor

[TokageItLab]

Editing filters in AnimationBlendTreeEditor was a pain since we had to make individual selections and switches for every bone when editing filters. This PR adds 3 useful options for editing filters.

• Fill Selected Children
  • Propagate that the filter is enabled to the children of the bones for which it is enabled
• Invert
  • Toggle enable and disable for all bones
• Clear
  • Disable filter for all bones

[adamscott]

As this is editor related, maybe the editor team should take a look at this, how to implement this PR editor-wide.
CC. @YuriSizov

[YuriSizov]

I don't really know the workflow this touches on, so I can't say if this is the best way to do it or not. If you want to give me a few examples of how it would be used by users, I can offer an opinion. Otherwise, we can just roll with it.

[TokageItLab]

The most common case is to select only the upper or lower body. For that currently, we needs to select all the bones, which is tedious. Also, due to the deep nesting, the ability to select children of the selected objects in the tree would make sense IMO.

Ideally, I would like to add multiple selections, but it is a bit complicated and will not be added in this PR.

[YuriSizov]

Also, due to the deep nesting, the ability to select children of the selected objects in the tree would make sense IMO.

Trees have a method to propagate checks (both upwards and downwards), so this can be done without extra controls, if it would be acceptable to always select all child bones when a parent bone is checked.

[TokageItLab]

@YuriSizov There is no such functionality in the current FillterEdit, so I assume it would need to be added. Do you mean to use call_recursive()?

[YuriSizov]

@TokageItLab I don't know what FilterEdit is. I was referring to functionality of Trees. There is TreeItem::propagate_check which allows to check and uncheck children of a tree item when it itself is checked or unchecked, and it allows to set an "intermediate" status to the tree item's parent items to indicate that they are partially selected.

If this behavior makes sense in your workflow, you should use it.

[TokageItLab]

Oh I see, I think FillSelectedChildren can be replaced with a bool option that determines if it uses propagate_check() or not, so I'll look at that later.

[YuriSizov]

I'll convert it into draft for now. Feel free to undraft it once it's ready to be reviewed again :)

[TokageItLab]

@YuriSizov I found that propagate_check is unusable, FilterEdit is just using Tree for display purposes. Also Bone does not treat the children as a group, they are parent-child relationships, and since each is independent and has only 1 column, so propagate_check will not work.

[SaracenOne]

While there's likely ways the usability of this can be improved further (I feel like it could benefit from keyboard shortcuts and maybe a right-click menu), this is still a massive usability improvement over the original filter track editor so I approve merging this.

[akien-mga]

Thanks!