Description
Summary
From #28403 (review):
Current logic
Extract all data coordinates xyz from the artist and feed them into
auto_scale_xyz().
This updates the xy_dataLim, zz_dataLim BBoxes via .Bbox.update_from_data_xy/x/y(), which in turn creates a Path and calls .Bbox.update_from_path().
This is quite a lot data pushing (and maybe copying) just to update dataLim bboxes.
Proposed logic
Separation of concerns: The Artists should have a function to get their data lims. These limits should be used to update the Bbox. Basically some Bbox.update_from_box, a kind of an in-place Bbox.union, which we don't seem to have.
Essentially, we have should implement a 3D variant of Collection.get_datalim` for 3D.
Proposed fix
Rough outline: We may start minimal with rolling a small
class _Bbox3d:
def __init__(self, points):
((self.xmin, self.xmax),
(self.ymin, self.ymax),
(self.zmin, self.zmax)) = points
def to_bbox_xy(self):
return Bbox(((self.xmin, self.xmax), (self.ymin, self.ymax)))
def to_bbox_zz(self):
# first component contains z, second is unused
return Bbox(((self.zmin, self.zmax), (0, 0)))
and implement _get_datalim3d() -> _Bbox3d on the 3d collections.
Then
def add_collection(col, autolim=True):
...
if autolim:
self.auto_scale_lim(col.get_datalim3d())
and
def auto_scale_lim(bbox3d):
...
self.dataLim_xy.update_from_box(bbox3d.to_bbox_xy())
self.dataLim_zz.update_from_box(bbox3d.to_bbox_zz())