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Animate rotating polytope

asked 2017-06-27 03:55:06 -0600

Akababa gravatar image

updated 2017-06-27 04:16:32 -0600

Hello, I'm trying to save an animation of a rotating polytope as a gif. So far the best I have is this:

n=49
t = (2*pi/n).n()
M=matrix([[cos(t),0,sin(t)],[0,1,0],[-sin(t),0,cos(t)]])
p=polytopes.cube()
vl = [v[:3] for v in p.vertices()]
sf = [p]
for i in range(n):
    vl = [M*v for v in vl]
    sf.append(Polyhedron(vl))
s=animate(sf)
s.gif(savefile="an.gif")

which outputs this:

https://media.giphy.com/media/3o7bufpi3S8f1dnlNm/giphy.gif (image description)

media.giphy.com/media/3o7bufpi3S8f1dnlNm/giphy.gif (Sorry, I need more karma to post links)

My questions: 1. how can I get the axes to stay constant so it looks more like a rotating object? 2. Is there a faster/cleaner way to do this?

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Comments

1

5 years ago, I managed to do animation of 3d sage graphics objects out of tachyon figures. See this blog post.

Sébastien gravatar imageSébastien ( 2017-06-27 06:50:37 -0600 )edit

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answered 2017-06-28 10:58:32 -0600

ndomes gravatar image

To get the rotation axis stay constant, add an enveloping circle making this invisible with opacity = 0. Further set aspect_ratio=(1,1,1) as an option of animate.

r = 2
y_axis = [r*vector((0,-1,0)),r*vector((0,1,0))]

var('alpha')
C = parametric_plot((r*cos(alpha),0,r*sin(alpha)),(alpha,0,2*pi),opacity=0)

n=19
t = (2*pi/n).n()
M=matrix([[cos(t),0,sin(t)],[0,1,0],[-sin(t),0,cos(t)]])
p=polytopes.cube()
vl = [v[:3] for v in p.vertices()]
sf = [] #[p]
for i in range(n):
    vl = [M*v for v in vl]
    sf.append(Polyhedron(vl).plot(color='green',opacity=0.5,frame=False)+ 
              C + line(y_axis,color='gold',thickness=2))
s=animate(sf,aspect_ratio=(1,1,1))
s.gif(savefile="an.gif")
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Thanks? Btw where can I find a list of all plot arguments?

Akababa gravatar imageAkababa ( 2017-06-28 21:48:40 -0600 )edit

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Asked: 2017-06-27 03:55:06 -0600

Seen: 111 times

Last updated: Jun 28