I want manim to spend 4 seconds animating the creation of a sector. Although the whole animation lasts 4 seconds, the creation portion is only half that. I've tried extending the run_time parameter but to get the full 4 seconds for creation I have to make the duration 8 seconds. The actual drawing is finished at 4 seconds but then I have an animation 50% longer than necessary with the second half just sitting there doing nothing. I must be doing something wrong but I'm very new to manim so I'm not sure what I'm doing wrong. Maybe it's the rate_func parameter.
MWE:
from manimlib.imports import *
class Circ(Scene):
def construct(self):
shape = Sector(color=GOLD_B,
fill_color=GOLD_B,
fill_opacity=1,
angle=360*DEGREES)
self.play(ShowCreation(shape,
lag_ratio=0,
rate_func=lambda t: linear(1 - t),
run_time=4*2)) # because we want 4 seconds for the circle's creation
I have tried it without the lag_ratio (not actually sure yet what that does). I borrowed the rate_func from Uncreate in animation.py. My current best guess is that this function is taking the full time of the run_time parameter but only looks like its using half. I have tried other functions, the original Uncreate is smooth. It is different but still doesn't appear to fill the full 4 seconds.
Thanks in advance.
The problem is the following, if we print the control points of the curve we see the following:
print(shape.points)
Returns:
[[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 3.33333333e-01 -8.16431199e-17 0.00000000e+00]
[ 6.66666667e-01 -1.63286240e-16 0.00000000e+00]
[ 1.00000000e+00 -2.44929360e-16 0.00000000e+00]
[ 1.00000000e+00 -2.44929360e-16 0.00000000e+00]
[ 1.00000000e+00 -2.61799388e-01 0.00000000e+00]
[ 8.92226904e-01 -5.21986659e-01 0.00000000e+00]
[ 7.07106781e-01 -7.07106781e-01 0.00000000e+00]
[ 7.07106781e-01 -7.07106781e-01 0.00000000e+00]
[ 5.21986659e-01 -8.92226904e-01 0.00000000e+00]
[ 2.61799388e-01 -1.00000000e+00 0.00000000e+00]
[-1.83697020e-16 -1.00000000e+00 0.00000000e+00]
[-1.83697020e-16 -1.00000000e+00 0.00000000e+00]
[-2.61799388e-01 -1.00000000e+00 0.00000000e+00]
[-5.21986659e-01 -8.92226904e-01 0.00000000e+00]
[-7.07106781e-01 -7.07106781e-01 0.00000000e+00]
[-7.07106781e-01 -7.07106781e-01 0.00000000e+00]
[-8.92226904e-01 -5.21986659e-01 0.00000000e+00]
[-1.00000000e+00 -2.61799388e-01 0.00000000e+00]
[-1.00000000e+00 1.22464680e-16 0.00000000e+00]
[-1.00000000e+00 1.22464680e-16 0.00000000e+00]
[-1.00000000e+00 2.61799388e-01 0.00000000e+00]
[-8.92226904e-01 5.21986659e-01 0.00000000e+00]
[-7.07106781e-01 7.07106781e-01 0.00000000e+00]
[-7.07106781e-01 7.07106781e-01 0.00000000e+00]
[-5.21986659e-01 8.92226904e-01 0.00000000e+00]
[-2.61799388e-01 1.00000000e+00 0.00000000e+00]
[ 6.12323400e-17 1.00000000e+00 0.00000000e+00]
[ 6.12323400e-17 1.00000000e+00 0.00000000e+00]
[ 2.61799388e-01 1.00000000e+00 0.00000000e+00]
[ 5.21986659e-01 8.92226904e-01 0.00000000e+00]
[ 7.07106781e-01 7.07106781e-01 0.00000000e+00]
[ 7.07106781e-01 7.07106781e-01 0.00000000e+00]
[ 8.92226904e-01 5.21986659e-01 0.00000000e+00]
[ 1.00000000e+00 2.61799388e-01 0.00000000e+00]
[ 1.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 1.00000000e+00 0.00000000e+00 0.00000000e+00]
[ 6.66666667e-01 0.00000000e+00 0.00000000e+00]
[ 3.33333333e-01 0.00000000e+00 0.00000000e+00]
[ 0.00000000e+00 0.00000000e+00 0.00000000e+00]]
We can see that many of the first control points are zero vectors, we would have to analyze the Sector source code to solve this problem, I suggest do something like:
class Circ(Scene):
def construct(self):
shape = Sector(
color=GOLD_B,
fill_color=GOLD_B,
fill_opacity=1,
stroke_width=4,
stroke_color=TEAL,
angle=360*DEGREES
)
shape.points = shape.points[32:-1] # <- because there are 33 zero vectors at the beginning and 1 at the end
self.play(
ShowCreation(
shape,
run_time=4,
rate_func=lambda t: linear(1-t)
)
)
self.wait()
Obviously, the amount of zeros can change depending on the Sector mobject that we use, so you will have to find a way to filter those zero vectors at the beginning that are not necessary, perhaps this can be easily corrected in the definition of the Sector class.