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Split-Flap Display Calculator

The following online calculator computes the formulas driving the flaps of a split-flap display. These formulas make it easy to model and animate a split-flap display using drivers in Blender, as demonstrated by this Tutorial.

Number of Flaps:

import bpy
from math import *

# Parameters:
# Number of flaps
Flaps = 10
# names of input shafts, from least significant to most significant
Shafts = [ "Circle",  "Circle.001",  "Circle.002", "Circle.003"]
# Number of frames per 1 digit
FramesPerDigit = 10
# Number of frames per pause
FramesPerPause = 20
# Sequence of numbers to display
NumbersToDisplay = [1234, 4235, 2012, 2345, 1999, 782]
# End of parameters

# Auxiliary functions
def ClearAnimationData():
    for objname in Shafts:
        obj = bpy.data.objects[objname]
        obj.animation_data_clear()
        
# pin to current frame
def PinToCurrentFrame(FrameCount):
    for objname in Shafts:
        obj = bpy.data.objects[objname]
        obj.keyframe_insert(data_path="rotation_euler", frame=FrameCount, index=1) # y only

def DisplayNumber( number ):
    # split number into digits. Number of digits = number of shafts
    for i in range(0, len(Shafts) ):
        currentdigits[i] = number % Flaps
        number = int(number / Flaps)        
        obj = bpy.data.objects[Shafts[i]]
        obj.rotation_euler.y = rads( - 360/Flaps * currentdigits[i])

# from degrees to radians        
def rads( angle ):
    return angle * pi / 180
    
ClearAnimationData()

FrCount = 1

currentdigits = [0 for i in Shafts]

# display initial number
DisplayNumber( NumbersToDisplay[0] )
PinToCurrentFrame(FrCount)

for i in range(1, len(NumbersToDisplay)):
    
    # change current number to the next number digit by digit until they are the same
    while True:
        NewNumber = NumbersToDisplay[i]
        # compare current with new digits
        done = True
        for j in range(0, len(Shafts)):
            newdigit =NewNumber % Flaps
            NewNumber = int(NewNumber / Flaps)
            if newdigit != currentdigits[j]:
                done = False
                currentdigits[j] = (currentdigits[j] + 1) % Flaps;
                obj = bpy.data.objects[Shafts[j]]
                obj.rotation_euler.y -= rads( 360/Flaps )
        
        FrCount += FramesPerDigit
        PinToCurrentFrame(FrCount)

if done:
            break
    
    FrCount += FramesPerPause
    PinToCurrentFrame(FrCount)

# and finally, make everything linear instead of bezier
for objname in Shafts:
    obj = bpy.data.objects[objname]
    fcurves = obj.animation_data.action.fcurves
    for fcurve in fcurves:
        for kf in fcurve.keyframe_points:
            kf.interpolation = 'LINEAR'

# Adjust total frame count in this animation
bpy.data.scenes[0].frame_end = FrCount