From dd6e99ab2ed6c0be22c386ffe729ce5c52c63894 Mon Sep 17 00:00:00 2001
From: Grant Sanderson <grant@3blue1brown.com>
Date: Sun, 16 Aug 2020 09:46:08 -0700
Subject: [PATCH] Make it possible to set a prefered direction for ShowCreation
 on surfaces

---
 manimlib/mobject/types/surface.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/manimlib/mobject/types/surface.py b/manimlib/mobject/types/surface.py
index 94455ced..51a1353b 100644
--- a/manimlib/mobject/types/surface.py
+++ b/manimlib/mobject/types/surface.py
@@ -24,6 +24,7 @@ class ParametricSurface(Mobject):
         "opacity": 1.0,
         "gloss": 0.3,
         "shadow": 0.4,
+        "prefered_creation_axis": 1,
         # For du and dv steps.  Much smaller and numerical error
         # can crop up in the shaders.
         "epsilon": 1e-5,
@@ -125,7 +126,9 @@ class ParametricSurface(Mobject):
         self.rgbas = interpolate(mobject1.rgbas, mobject2.rgbas, alpha)
         return self
 
-    def pointwise_become_partial(self, smobject, a, b, axis=1):
+    def pointwise_become_partial(self, smobject, a, b, axis=None):
+        if axis is None:
+            axis = self.prefered_creation_axis
         assert(isinstance(smobject, ParametricSurface))
         self.points[:] = smobject.points[:]
         if a <= 0 and b >= 1: