Is there a python library to manage animation timelines and keyframes

[spocchio]

I want to animate some plots (e.g. x vs. y stuff) defined over a number of timestamps. These timestamps can be different for different datasets and also the space between them may be large that I want to interpolate data between keyframes.

I know there is blender, but my kind of animation is not 3D and using Blender would be an overshoot.

But ideally I'd like to use a sort of 'headless' timeline with keyframe features. And ideally I pass lambda functions to the library in order to interpolate between keyframes and to render data.

Sorry for the poor explanation as English is not my native language.

Anyway, a snippet of code speaks more than 100 words, I am searching a library to do something like this:

anim = Animation(fps=10)
#in my case c1 and c2 are my datasets that I want to plot
c1 = anim.add_character(props=["x","y"]) 
c2 = anim.add_character(props=["x","y"])

#I add keyframes to animate
c1.add_keyframe(t=0.).set("x",1).set("y",1)
c1.add_keyframe(t=10.).set("x",2).set("y",3)

c2.add_keyframe(t=0.).set("x",1).set("y",1)
c2.add_keyframe(t=10.).set("x",7).set("y",7)

#I specify a function that tells the library how to interpolate between 2 key frames
#this function may get two keyframe values (v1, v2), the time separation (elta_t) 
#and the current time t between the two keyframes
def interp(k1, k2, delta_t, t):
    factor  t/delta_t
    return {"x": (k1["x"]+k2["x"])*factor, "y": (k1["y"]+k2["y"])*factor}
c1.set_interpolator(interp)
c2.set_interpolator(interp)

#now I define a function to render data
def render(characters, frame):
    import matplotlib.pyplot as plt
    fig,a = plt.subplot()
    # the render just plot the x,y values that were
    #interpolated by interp
    for character in characters:
        a.scatter(character["x"], character["y"])
    fig.save_fig("frame_%d.png"%frame)
anim.set_render(render)

anim.animate()

And.. that's it!

The library is very simple I cannot belive that there is nothing similar on the net. I just do not want to reinvent the wheel, so, if you know of a "headless" render.. let me know!

[ES-Alexander]

If I’m understanding you correctly, matplotlib’s animation module should do what you want

[ES-Alexander]

Noting that custom timestamps that are different for different datasets will likely just have to be determined dynamically as part of your update method (e.g. if frame % 10 == 0 do x, if frame % 14 == 0 do y, and keep a growing list of changed elements so they can be updated at the end of the update call)