GrowArrow animation fixed, (fixes #1002) (#1003)

Author: sparshg

manim/animation/growing.py

@@ -57,6 +57,13 @@ def __init__(self, arrow: "Arrow", **kwargs) -> None:
         point = arrow.get_start()
         super().__init__(arrow, point, **kwargs)
 
+    def create_starting_mobject(self) -> "Mobject":
+        start_arrow = self.mobject.copy()
+        start_arrow.scale(0, scale_tips=True, about_point=self.point)
+        if self.point_color:
+            start_arrow.set_color(self.point_color)
+        return start_arrow
+
 
 class SpinInFromNothing(GrowFromCenter):
     def __init__(self, mobject: "Mobject", path_arc: float = PI, **kwargs) -> None:

manim/mobject/geometry.py

@@ -856,6 +856,7 @@ def scale(self, factor, scale_tips=False, **kwargs):
 
         if scale_tips:
             VMobject.scale(self, factor, **kwargs)
+            self.set_stroke_width_from_length()
             return self
 
         has_tip = self.has_tip()