Merge pull request #407 from 3b1b/clacks

Clacks

manimlib/animation/creation.py

@@ -113,6 +113,17 @@ class Write(DrawBorderThenFill):
         else:
             self.run_time = 2
 
+
+class ShowIncreasingSubsets(Animation):
+    def __init__(self, group, **kwargs):
+        self.all_submobs = group.submobjects
+        Animation.__init__(self, group, **kwargs)
+
+    def update_mobject(self, alpha):
+        n_submobs = len(self.all_submobs)
+        index = int(alpha * n_submobs)
+        self.mobject.submobjects = self.all_submobs[:index]
+
 # Fading
 
 

manimlib/camera/camera.py

@@ -392,7 +392,10 @@ class Camera(object):
             vmobject
         )
         ctx.set_line_width(
-            width * self.cairo_line_width_multiple
+            width * self.cairo_line_width_multiple *
+            # This ensures lines have constant width
+            # as you zoom in on them.
+            (self.get_frame_width() / FRAME_WIDTH)
         )
         ctx.stroke_preserve()
         return self

manimlib/for_3b1b_videos/pi_creature_scene.py

@@ -298,7 +298,7 @@ class TeacherStudentsScene(PiCreatureScene):
                 "raise_left_hand",
             ])
             kwargs["target_mode"] = target_mode
-        student = self.get_students()[kwargs.get("student_index", 1)]
+        student = self.get_students()[kwargs.get("student_index", 2)]
         return self.pi_creature_says(
             student, *content, **kwargs
         )
@@ -309,7 +309,7 @@ class TeacherStudentsScene(PiCreatureScene):
         )
 
     def student_thinks(self, *content, **kwargs):
-        student = self.get_students()[kwargs.get("student_index", 1)]
+        student = self.get_students()[kwargs.get("student_index", 2)]
         return self.pi_creature_thinks(student, *content, **kwargs)
 
     def change_all_student_modes(self, mode, **kwargs):

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 = {

manimlib/mobject/numbers.py

@@ -105,7 +105,10 @@ class DecimalNumber(VMobject):
         full_config.update(self.initial_config)
         full_config.update(config)
         new_decimal = DecimalNumber(number, **full_config)
-        new_decimal.match_height(self)
+        # new_decimal.match_height(self)
+        new_decimal.scale(
+            self[0].get_height() / new_decimal[0].get_height()
+        )
         new_decimal.move_to(self, self.edge_to_fix)
         new_decimal.match_style(self)
 
@@ -129,3 +132,6 @@ class Integer(DecimalNumber):
 
     def increment_value(self):
         self.set_value(self.get_value() + 1)
+
+    def get_value(self):
+        return int(np.round(super().get_value()))