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Merge pull request #10001 from eric-wieser/more-normals
MAINT/BUG: Don't use 5-sided quadrilaterals in Axes3D.plot_surface
2 parents 6ceac0d + b0d7e4b commit 2887c49

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-15164
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‎lib/matplotlib/cbook/__init__.py

Lines changed: 39 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -2013,6 +2013,45 @@ def method(self, *args, **kwargs):
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return cls
20142014

20152015

2016+
def _array_perimeter(arr):
2017+
"""
2018+
Get the elements on the perimeter of ``arr``,
2019+
2020+
Parameters
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----------
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arr : ndarray, shape (M, N)
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The input array
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Returns
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-------
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perimeter : ndarray, shape (2*(M - 1) + 2*(N - 1),)
2028+
The elements on the perimeter of the array::
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2030+
[arr[0,0] ... arr[0,-1] ... arr[-1, -1] ... arr[-1,0] ...]
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2032+
Examples
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--------
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>>> i, j = np.ogrid[:3,:4]
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>>> a = i*10 + j
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>>> a
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array([[ 0, 1, 2, 3],
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[10, 11, 12, 13],
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[20, 21, 22, 23]])
2040+
>>> _array_perimeter(arr)
2041+
array([ 0, 1, 2, 3, 13, 23, 22, 21, 20, 10])
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"""
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# note we use Python's half-open ranges to avoid repeating
2044+
# the corners
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forward = np.s_[0:-1] # [0 ... -1)
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backward = np.s_[-1:0:-1] # [-1 ... 0)
2047+
return np.concatenate((
2048+
arr[0, forward],
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arr[forward, -1],
2050+
arr[-1, backward],
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arr[backward, 0],
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))
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20162055
@contextlib.contextmanager
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def _setattr_cm(obj, **kwargs):
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"""Temporarily set some attributes; restore original state at context exit.

‎lib/mpl_toolkits/mplot3d/axes3d.py

Lines changed: 42 additions & 53 deletions
Original file line numberDiff line numberDiff line change
@@ -1622,15 +1622,15 @@ def plot_surface(self, X, Y, Z, *args, norm=None, vmin=None,
16221622
# Strides have priority over counts in classic mode.
16231623
# So, only compute strides from counts
16241624
# if counts were explicitly given
1625-
if has_count:
1626-
rstride = int(max(np.ceil(rows / rcount), 1))
1627-
cstride = int(max(np.ceil(cols / ccount), 1))
1625+
compute_strides = has_count
16281626
else:
16291627
# If the strides are provided then it has priority.
16301628
# Otherwise, compute the strides from the counts.
1631-
if not has_stride:
1632-
rstride = int(max(np.ceil(rows / rcount), 1))
1633-
cstride = int(max(np.ceil(cols / ccount), 1))
1629+
compute_strides = not has_stride
1630+
1631+
if compute_strides:
1632+
rstride = int(max(np.ceil(rows / rcount), 1))
1633+
cstride = int(max(np.ceil(cols / ccount), 1))
16341634

16351635
if 'facecolors' in kwargs:
16361636
fcolors = kwargs.pop('facecolors')
@@ -1648,71 +1648,60 @@ def plot_surface(self, X, Y, Z, *args, norm=None, vmin=None,
16481648
if shade and cmap is not None and fcolors is not None:
16491649
fcolors = self._shade_colors_lightsource(Z, cmap, lightsource)
16501650

1651+
# evenly spaced, and including both endpoints
1652+
row_inds = list(range(0, rows-1, rstride)) + [rows-1]
1653+
col_inds = list(range(0, cols-1, cstride)) + [cols-1]
1654+
1655+
colset = [] # the sampled facecolor
16511656
polys = []
1652-
# Only need these vectors to shade if there is no cmap
1653-
if cmap is None and shade :
1654-
totpts = int(np.ceil((rows - 1) / rstride) *
1655-
np.ceil((cols - 1) / cstride))
1656-
v1 = np.empty((totpts, 3))
1657-
v2 = np.empty((totpts, 3))
1658-
# This indexes the vertex points
1659-
which_pt = 0
1660-
1661-
1662-
#colset contains the data for coloring: either average z or the facecolor
1663-
colset = []
1664-
for rs in range(0, rows-1, rstride):
1665-
for cs in range(0, cols-1, cstride):
1666-
ps = []
1667-
for a in (X, Y, Z):
1668-
ztop = a[rs,cs:min(cols, cs+cstride+1)]
1669-
zleft = a[rs+1:min(rows, rs+rstride+1),
1670-
min(cols-1, cs+cstride)]
1671-
zbase = a[min(rows-1, rs+rstride), cs:min(cols, cs+cstride+1):][::-1]
1672-
zright = a[rs:min(rows-1, rs+rstride):, cs][::-1]
1673-
z = np.concatenate((ztop, zleft, zbase, zright))
1674-
ps.append(z)
1675-
1676-
# The construction leaves the array with duplicate points, which
1677-
# are removed here.
1678-
ps = list(zip(*ps))
1679-
ps2 = [ps[0]] + [ps[i] for i in range(1, len(ps)) if ps[i] != ps[i-1]]
1680-
avgzsum = sum(p[2] for p in ps2)
1681-
polys.append(ps2)
1657+
for rs, rs_next in zip(row_inds[:-1], row_inds[1:]):
1658+
for cs, cs_next in zip(col_inds[:-1], col_inds[1:]):
1659+
ps = [
1660+
# +1 ensures we share edges between polygons
1661+
cbook._array_perimeter(a[rs:rs_next+1, cs:cs_next+1])
1662+
for a in (X, Y, Z)
1663+
]
1664+
# ps = np.stack(ps, axis=-1)
1665+
ps = np.array(ps).T
1666+
polys.append(ps)
16821667

16831668
if fcolors is not None:
16841669
colset.append(fcolors[rs][cs])
1685-
else:
1686-
colset.append(avgzsum / len(ps2))
1687-
1688-
# Only need vectors to shade if no cmap
1689-
if cmap is None and shade:
1690-
i1, i2, i3 = 0, int(len(ps2)/3), int(2*len(ps2)/3)
1691-
v1[which_pt] = np.array(ps2[i1]) - np.array(ps2[i2])
1692-
v2[which_pt] = np.array(ps2[i2]) - np.array(ps2[i3])
1693-
which_pt += 1
1694-
if cmap is None and shade:
1695-
normals = np.cross(v1, v2)
1696-
else :
1697-
normals = []
16981670

1671+
def get_normals(polygons):
1672+
"""
1673+
Takes a list of polygons and return an array of their normals
1674+
"""
1675+
v1 = np.empty((len(polygons), 3))
1676+
v2 = np.empty((len(polygons), 3))
1677+
for poly_i, ps in enumerate(polygons):
1678+
# pick three points around the polygon at which to find the normal
1679+
# doesn't vectorize because polygons is jagged
1680+
i1, i2, i3 = 0, len(ps)//3, 2*len(ps)//3
1681+
v1[poly_i, :] = ps[i1, :] - ps[i2, :]
1682+
v2[poly_i, :] = ps[i2, :] - ps[i3, :]
1683+
return np.cross(v1, v2)
1684+
1685+
# note that the striding causes some polygons to have more coordinates
1686+
# than others
16991687
polyc = art3d.Poly3DCollection(polys, *args, **kwargs)
17001688

17011689
if fcolors is not None:
17021690
if shade:
1703-
colset = self._shade_colors(colset, normals)
1691+
colset = self._shade_colors(colset, get_normals(polys))
17041692
polyc.set_facecolors(colset)
17051693
polyc.set_edgecolors(colset)
17061694
elif cmap:
1707-
colset = np.array(colset)
1708-
polyc.set_array(colset)
1695+
# doesn't vectorize because polys is jagged
1696+
avg_z = np.array([ps[:,2].mean() for ps in polys])
1697+
polyc.set_array(avg_z)
17091698
if vmin is not None or vmax is not None:
17101699
polyc.set_clim(vmin, vmax)
17111700
if norm is not None:
17121701
polyc.set_norm(norm)
17131702
else:
17141703
if shade:
1715-
colset = self._shade_colors(color, normals)
1704+
colset = self._shade_colors(color, get_normals(polys))
17161705
else:
17171706
colset = color
17181707
polyc.set_facecolors(colset)

‎lib/mpl_toolkits/tests/baseline_images/test_mplot3d/mixedsubplot.pdf

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‎lib/mpl_toolkits/tests/baseline_images/test_mplot3d/mixedsubplot.png

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