Make it easier to change background color

manim/camera/camera.py

@@ -89,11 +89,12 @@ def __init__(self, video_quality_config, background=None, **kwargs):
             "frame_height",
             "frame_width",
             "frame_rate",
-            "background_color",
-            "background_opacity",
         ]:
             setattr(self, attr, kwargs.get(attr, config[attr]))
 
+        for attr in ["background_color", "background_opacity"]:
+            setattr(self, f"_{attr}", kwargs.get(attr, config[attr]))
+
         # This one is in the same boat as the above, but it doesn't have the
         # same name as the corresponding key so it has to be handled on its own
         self.max_allowable_norm = config["frame_width"]
@@ -117,6 +118,24 @@ def __deepcopy__(self, memo):
         self.canvas = None
         return copy.copy(self)
 
+    @property
+    def background_color(self):
+        return self._background_color
+
+    @background_color.setter
+    def background_color(self, color):
+        self._background_color = color
+        self.init_background()
+
+    @property
+    def background_opacity(self):
+        return self._background_opacity
+
+    @background_opacity.setter
+    def background_opacity(self, alpha):
+        self._background_opacity = alpha
+        self.init_background()
+
     def type_or_raise(self, mobject):
         """Return the type of mobject, if it is a type that can be rendered.
 

manim/scene/scene.py

@@ -80,6 +80,10 @@ def __init__(self, renderer=None, **kwargs):
 
         self.setup()
 
+    @property
+    def camera(self):
+        return self.renderer.camera
+
     def render(self):
         """
         Render this Scene.

tests/test_color.py

@@ -1,8 +1,26 @@
 import pytest
-from manim import Camera, tempconfig, config
+import numpy as np
+
+from manim import Camera, Scene, tempconfig, config
 
 
 def test_import_color():
     import manim.utils.color as C
 
     C.WHITE
+
+
+def test_background_color():
+    S = Scene()
+    S.camera.background_color = "#ff0000"
+    S.renderer.update_frame(S)
+    assert np.all(S.renderer.get_frame()[0, 0] == np.array([255, 0, 0, 255]))
+
+    S.camera.background_color = "#436f80"
+    S.renderer.update_frame(S)
+    assert np.all(S.renderer.get_frame()[0, 0] == np.array([67, 111, 128, 255]))
+
+    S.camera.background_color = "#bbffbb"
+    S.camera.background_opacity = 0.5
+    S.renderer.update_frame(S)
+    assert np.all(S.renderer.get_frame()[0, 0] == np.array([187, 255, 187, 127]))