Eraser Tool Options' Size takes Fixed or Pressure and a Variation as the
Blob Brush's does: the tool records the pen, and path.eraseRegion outlines
the squashed drag at the pen's widths, stretched back to the tip's angle
and roundness. The pressure parsing and outline move to draw2's common
helpers, shared by both commands.
Blob Brush Tool Options' Size takes Fixed or Pressure and a Variation, as
the brush options' Size does: with Pressure the brush is Size − Variation
wide where the pen presses lightest and Size + Variation where it presses
hardest. The tool records the pen pressure of each point and shows each
step of the drag as wide as the pen pressed there; path.blob takes
[x, y, pressure] points with sizeMode and sizeVariation and outlines the
stroke with that width profile. A stroke without pressure keeps the Size,
and Fixed with no variation stays the default.
https://helpx.adobe.com/illustrator/desktop/paint-and-fill/learn-painting-basics/blob-brush-options-and-best-practices.html
A Blob Brush stroke used to merge with every closed path of its fill
color and no stroke that it touched, anywhere in the document, across
layers and groups and past objects of other kinds. It now merges with
the topmost such path it touches, and with the other touched matching
paths in the same group or layer that are next to that path in
stacking order, with no other kind of object between them. Merge only
with selection still limits the candidates to selected paths. The
merged path keeps the topmost path's id and place.
Deleting a point of a finished path with the Curvature tool sent
path.removeAnchor, which refits the two segments that met at the point so
one curve follows them. The path kept the bend of the deleted point
instead of curving through the points that remain.
The tool now sends path.removeAnchor with curvature: true, which uses the
new curvature_remove. Each smooth neighbor takes new handles from its new
neighbors, and an end beside one of them takes its end handle again. A
corner neighbor keeps its handle directions, and its handle on the new
segment scales with the segment's chord. With two points left, the points
that curve lose their handles. Object > Path > Remove Anchor Points and
the Delete Anchor Point tool still refit the curve.
bflatastic