From e2e6fad1140b521c3710132bb2f8a68a74ab2dbe Mon Sep 17 00:00:00 2001
From: Grant Sanderson <grant@3blue1brown.com>
Date: Thu, 17 Jan 2019 14:10:52 -0800
Subject: [PATCH] Add Circle.get_point_from_angle, and arc_center config
 variable for arc

---
 manimlib/mobject/geometry.py | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/manimlib/mobject/geometry.py b/manimlib/mobject/geometry.py
index eba3f001..093118d9 100644
--- a/manimlib/mobject/geometry.py
+++ b/manimlib/mobject/geometry.py
@@ -23,6 +23,7 @@ class Arc(VMobject):
         "start_angle": 0,
         "num_anchors": 9,
         "anchors_span_full_range": True,
+        "arc_center": ORIGIN,
     }
 
     def __init__(self, angle, **kwargs):
@@ -50,6 +51,7 @@ class Arc(VMobject):
             anchors, handles1, handles2
         )
         self.scale(self.radius, about_point=ORIGIN)
+        self.shift(self.arc_center)
 
     def add_tip(self, tip_length=0.25, at_start=False, at_end=True):
         # clear out any old tips
@@ -180,6 +182,14 @@ class Circle(Arc):
             np.sqrt(mobject.get_width()**2 + mobject.get_height()**2))
         self.scale(buffer_factor)
 
+    def get_point_from_angle(self, angle):
+        start_angle = angle_of_vector(
+            self.points[0] - self.get_center()
+        )
+        return self.point_from_proportion(
+            (angle - start_angle) / TAU
+        )
+
 
 class Dot(Circle):
     CONFIG = {