From 046caa763215d9b9d35d029c52002583241bb92a Mon Sep 17 00:00:00 2001
From: Grant Sanderson <grant@3blue1brown.com>
Date: Sun, 7 Jun 2020 12:24:54 -0700
Subject: [PATCH] Bug fixes

---
 manimlib/mobject/types/surface.py | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/manimlib/mobject/types/surface.py b/manimlib/mobject/types/surface.py
index 23cc3781..2adb1be0 100644
--- a/manimlib/mobject/types/surface.py
+++ b/manimlib/mobject/types/surface.py
@@ -5,6 +5,7 @@ from PIL import Image
 
 from manimlib.constants import *
 from manimlib.mobject.mobject import Mobject
+from manimlib.utils.bezier import interpolate
 from manimlib.utils.color import color_to_rgba
 from manimlib.utils.images import get_full_raster_image_path
 from manimlib.utils.space_ops import normalize_along_axis
@@ -68,6 +69,8 @@ class ParametricSurface(Mobject):
         # normals, this returns an Nx3 array whose rows are elements from this grid
         # in such such a way that successive triplets of points form triangles covering
         # the grid.
+        if array.size == 0:
+            return array
         dim = array.shape[1]
         nu, nv = self.resolution
         assert(array.shape == (nu * nv, dim))
@@ -100,15 +103,14 @@ class ParametricSurface(Mobject):
         )
         return normalize_along_axis(normals, 1)
 
-    def set_color(self, color, opacity=1.0, gloss=None, family=True):
+    def set_color(self, color, opacity=1.0, family=True):
         # TODO, allow for multiple colors
         rgba = color_to_rgba(color, opacity)
         self.rgbas = np.array([rgba])
-        if gloss is not None:
-            self.set_gloss(gloss)
         if family:
             for submob in self.submobjects:
-                submob.set_color(color, opacity, gloss, family)
+                submob.set_color(color, opacity, family)
+        return self
 
     def set_opacity(self, opacity, family=True):
         self.rgbas[:, 3] = opacity
@@ -117,6 +119,10 @@ class ParametricSurface(Mobject):
                 sm.set_opacity(opacity, family)
         return self
 
+    def interpolate_color(self, mobject1, mobject2, alpha):
+        self.rgbas = interpolate(mobject1.rgbas, mobject2.rgbas, alpha)
+        return self
+
     def get_shader_data(self):
         s_points, du_points, dv_points = [
             self.get_triangle_ready_array(array)
@@ -138,7 +144,8 @@ class ParametricSurface(Mobject):
 
 class SGroup(ParametricSurface):
     def __init__(self, *parametric_surfaces, **kwargs):
-        super().__init__(**kwargs)
+        # TODO, separate out the surface type...again
+        super().__init__(uv_func=None, **kwargs)
         self.add(*parametric_surfaces)
 
     def init_points(self):