There isn’t a tag for smooth day of the month rotation. I guess the reason is that the number days in a month varies, so there is no fixed rotation speed that could be applied.
For a 31-day date dial, the general formula to positioning dial to the date would be: ´#Dd#*11.61#`
(31 days in 360° gives you the 11.61°). You can add or subtract values, depending on how you dial looks like. In the 31-day dial below the rotation formula would be: (#Dd#*11.61-11.61)
That formula is the basis for a smooth rotation. The idea is to add a smooth rotation to that formula, #DWFHS# is good enough for this purpose.
I figured there are 2 solution to have a smooth rotating
1. Using 4 dials,
each with their own rotation speed, and using opacity to display one the dials depending on how many days there are in a month:
Dial 1, 1-31 days:
- Rotation:
(#DWFHS#/360*11.61+#Dd#*11.61-11.61) - Opacity:
$#DIM#=31?100:0$
Dial 2, 1-30 days:
- Rotation:
(#DWFHS#/360*12+#Dd#*12-12) - Opacity:
$#DIM#=30?100:0$
Dial 3, 1-29 days:
- Rotation:
(#DWFHS#/360*12.41+#Dd#*12.41-12.41) - Opacity:
$#DIM#=29?100:0$
Dial 4, 1-28 days:
- Rotation:
(#DWFHS#/360*12.86+#Dd#*12.86-12.86) - Opacity:
$#DIM#=28?100:0$
2. Using a single dial,
and transition/rotation to the 1st of the month when the end of the month has been reached.
So for this we can use the 31-day dial formula and add a condition and rotate onwards if #DIM# = #Dd#. I prefer this not to be jumpy but also smooth, so I add the interpAccel function to it.
The formula is:
$#DIM#=#Dd#?(#DWFHS#/360*11.61+#Dd#*11.61-11.61)+((interpAccel(#Dsm#,0,1,1))*11.65*(31-#DIM#)):(#DWFHS#/360*11.61+#Dd#*11.61-11.61)$
Explanation:
If condition is met, the rotate forwards by the number of days require. So in the case of February )non-leap year), there are only 28 days, so I need to rotate by 31-28=3 days. If condition is not met rotate as defined.
Working example with both options. Inner dial using a single dial, outer one is composed of the option with the 4 dials:
Advantage of the 4 dials: you’ll always have a smooth rotation
Disadvantage of a single dial: the dial rotates to “31” even if the current month may not have that many days, which seem a bit awkward.
But maybe someone a better idea…
