This patch adds several tools and options to the weight paint mode of Grease Pencil.
* Blur tool: smooths out vertex weights, by calculating a gaussian blur of adjacent vertices.
* Average tool: painting the average weight from all weights under the brush.
* Smear tool: smudges weights by grabbing the weights under the brush and 'dragging' them.
* With the + and - icons in the toolbar, the user can easily switch between adding and subtracting weight while drawing weights.
* With shortcut `D` you can toggle between these two.
* The auto-normalize options ensures that all bone-deforming vertex groups add up to 1.0 while weight painting.
* With `Ctrl-F` a radial control for weight is invoked (in addition to the radial controls for brush size and strength).
* With `Ctrl-RMB` the user can sample the weight. This sets the brush Weight from the weight under the cursor.
* When painting weights in vertex groups for bones, the user can quickly switch to another vertex group by clicking on a bone with `Ctrl-LMB`.
For this to work, follow these steps:
* Select the armature and switch to Pose Mode.
* Select your Grease Pencil object and switch immediately to Weight Paint Mode.
* Select a bone in the armature with `Ctrl-LMB`. The corresponding vertex group is automatically activated.
Pull Request: https://projects.blender.org/blender/blender/pulls/106663