Calculating A Moon Dial - Help Please

Ok...I'm horrible at math...I usually figure out
things after a lot of time-consuming trail and error,
not knowing half of what I'm doing along the way. =)

* * *

I want to make a moon dial, like the ones used in
mechanical grandfather clocks and classy watches.
The moon dial simply a disk that turns 360 degrees
once a moon.

So...what I've learned thus far is that basically the moon
moves through its ecliptic thus:

360 degrees / 29.53 days = 12.19 degrees per day

Of course this is very general. There are variations...but
this would serve as a good starting point.

Now I'd like to use this bit of code I use
for clock hour hands...to rotate an object, in
this case a disk.

I worked out these numbers:

708.72 hours in a moon cycle
360 / 708.72 = 0.507958

And I'm wondering if I can use llGetWallclock base
to derive the rotation I need for the llEuler2Rot
calculation. There's probably a much better way.


This is what I use for some hour hands:

float now = llGetWallclock();
float minute = (integer)now / 60;
float hour = minute / 60;

// For 12 Hour Clock Hour Hand
rotation hand_rot = llEuler2Rot(<0, 30 * hour * DEG_TO_RAD, 0>;
llSetLocalRot(hand_rot);

* * *

And so now...

// For the Moon???????
rotation hand_rot = llEuler2Rot(<0, 0.507958 * hour?? * DEG_TO_RAD, 0>;
llSetLocalRot(hand_rot);


Any help would be grandly appreciated!!
--Infrared

Hi Infrared, long time no see.

Problem with using llGetWallClock is that the maximum it can ever reach is 23:59:59 (hrs:minec) whereas your period, the length of time it'll take for your hand to rotate 360deg is 29.53 days. Therefore you'll need to include a date function and start from a specific date to give you a full period, this is best done using the llGetUnixTime function:

From that you just divide by 29.53 days or 2,551,392 seconds to give you a float which if you multiply by 360deg or 2*pi radians gives you your angle for your clock hand.

so,


becomes


EDIT: 2,551,392 seconds, not 2,351,392 seconds, in 29.53days.

Awesome, Nand! That's it! You have a big brain. =)

And yeah...long time no see...I'm overdue for visit to your gallery. =)

Thanks again!

-- Infrared

Hey Nand --

According to the google calculator:

29.53 days = 2551392 seconds, is your number a typo? =)

- Infrared

Sure is Infrared,

erm I mean it was just there to check you were paying attention.