Beginning lost lecture project

active_projects/lost_lecture.py

@@ -0,0 +1,52 @@
+from __future__ import absolute_import
+from big_ol_pile_of_manim_imports import *
+
+
+class ShowEmergingEllipse(Scene):
+    def construct(self):
+        circle = Circle(num_anchors=50, radius=3, color=BLUE)
+        e_point = 2 * RIGHT
+        e_dot = Dot(e_point, color=YELLOW)
+        lines = VGroup(*[
+            Line(e_point, circle.point_from_proportion(a))
+            for a in np.linspace(0, 1, 4 * 49)
+        ])
+        lines.set_stroke(width=1)
+        for line in lines:
+            line.generate_target()
+            line.target.rotate(90 * DEGREES)
+
+        fade_rect = FullScreenFadeRectangle()
+        line = lines[20]
+        line_dot = Dot(line.get_center(), color=YELLOW)
+
+        words = TextMobject("Rotate $90^\\circ$ \\\\ about center")
+        words.add_to_back(words.copy().set_stroke(BLACK, 2))
+        words.next_to(line_dot, RIGHT)
+
+        self.play(
+            LaggedStart(ShowCreation, lines),
+            Animation(VGroup(e_dot, circle))
+        )
+        self.add(lines.copy().set_stroke(LIGHT_GREY, 0.5))
+        self.add(e_dot, circle)
+        self.wait()
+        self.play(FadeIn(fade_rect), Animation(line))
+        self.play(
+            GrowFromCenter(line_dot),
+            FadeInFromDown(words)
+        )
+        self.add_foreground_mobjects(line.copy().set_stroke(LIGHT_GREY, 0.5))
+        self.play(MoveToTarget(line, path_arc=90 * DEGREES))
+        self.wait()
+        self.play(
+            FadeOut(fade_rect),
+            FadeOut(line_dot),
+            FadeOut(words),
+            Animation(line)
+        )
+        self.play(
+            LaggedStart(MoveToTarget, lines, run_time=4),
+            Animation(VGroup(e_dot, circle))
+        )
+        self.wait()