Hands on a clockface (resolved)

How to you calculate the angle of the MinuteHand and the HourHand of a clock, when you are given the time as the number of seconds since midnight?

Angles in radians would be fine.

Thanks.

EDIT: I don't want the angle between the hands, just the angle individually: say its 3:00am, the minute hand is at 0 radians (0 degrees) and the hour hand is at 1.570796 radians (90 degrees).

mhandAngle = (time MOD 60^2) * 2 * PI / 60^2
hhandAngle = (time MOD 60^3) * 2 * PI / 60^3

of course it could be completely wrong

for hours: angle = 2 * pi * h / 12 = pi * h / 6
for minute / seconds: angle = 2 * pi * h / 60 = pi * h / 30

[edit]: this is my 911th post.

i think he wanted the exact location of the hands

Go ahead, put in 6:00, or 6:30. You will get pi for hours and 0 and pi (respectively) for the other.

I don't see what you mean.

Another way of asking the same question...

How many radians does the hour hand travel through per second?
How many radians does the minute hand travel through per second?

:confused:

My ropey maths tells me that the minute hand travels through 0.0000290882087 radians per second, and the hour hand 0.0000005076956996 radians per second. Is this right?

Since a second hand does 6 degrees per sec, divide by 60 to get minute hand degrees per second and divide by 60 again to get hour hand, then convert each of those to radians.

If I multiply these figures by the number of seconds since midnight I should be left with the correct angle for each hand. Does this seem logical?

I think in degrees, not radians but here's something I'll cook up on the go.
rotate the hands clockwise where 0 degrees is striaght up.

minangle = minutes*60
hourangle = (hours*60)+minutes

I normally use degrees too but the framework math.sin() and math.cos() have to be supplied with radians in order to work.

w00t!

Took 3 expressos to get this finished. I'll finish polishing my Clox0r class and post it up here when all the bugs have been eradicated.

Meanwhile, here's a screenshot...

http://www.vbforums.com/attachment.p...postid=1785114

Graphically, the hands of the clock are accurate to a 10,000,000th of a second. You can even get it to sweep smoothly around the clock (like on Back To The Future :lol: )!

The constructor lets you specify the radius of the clockface, the x,y position of the centre of it and the graphics object you want to draw the clock on. (Just had it drawing onto a Button control :D).

Mk2.

http://www.vbforums.com/attachment.p...postid=1785398

Clox0r drawing itself onto a Button control's Graphics object via button_Paint(). Clicking the button pops up a message box, meanwhile the clock keeps ticking on the button!

:cool:

omg. i simply must have it
:p

My finely honed superhero senses suggest that there may have been a soupçon of sarcasm in that last comment.

I can take it. Mummy says I'm a grown up now.

Eat shadows punk!...

http://www.vbforums.com/attachment.p...postid=1785672

but can it run BACKWARDS???

You feed it Timespan Objects and it will go in whatever direction you want, feed it the right times and you can get the hour and minute hands to spin in opposite directions :eek:

VB Code:

dim cf as Clox0r = new Clox0r(...)
...
 
dim temp as Timespan = new Timespan(0)
 
for i as integer = 0 to 99999
cf.Time = cf.Time.AddMinutes(59)
cf.Draw
Delay()
next i

Does it tell the time?

Quote:

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Originally posted by mendhak
Does it tell the time?

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Does it tell the what now? Stop trying to complicate matters reptile.

Quote:

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Originally posted by wossname
My finely honed superhero senses suggest that there may have been a soupçon of sarcasm in that last comment.

I can take it. Mummy says I'm a grown up now.

Eat shadows punk!...

http://www.vbforums.com/attachment.p...postid=1785672

---

Kool off kitty...
I meant no harm, just like to joke sometimes. its a nice control :wave:

Too cool. A lawyer/friend of mine has a timepiece that runs backwards, and I'd love to give him this for his computer, as a joke!

I'm just writing the documentation now. Should be able to post it tonight.

What algorithm did you use to find the position of the hands?

can I have it? let me know. i need it to run backwards, though.

Quote:

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Originally posted by Darkwraith
What algorithm did you use to find the position of the hands?

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I wrote a Hand class and as a Constructor argument I pass in the speed of the particular hand in question. Then the class multiplies this value by the ticks property of the time. The speed is expressed as the number of radians that the hand passes through per tick (Pretty microscopic number!). And so this multiplication gives the angle that the hand shoulld be shown at. This is typically several million radians.

The Clox0r class (the whole thing) will be released as part of the Sandpaper library (see the Project Communication forum here)

Source will not be available I'm afraid. And yes, it will be able to run backwards :rolleyes: Stay tuned.

ok... I see now. Thanks. :)

10-4. he'll have to wait.

I mean that I know how he did it from his pseudocode and why he did it as such. :)

If you are interested, the shape of the hands was defined as an array of PointF objects. the .X property of which represented the Angle of the point in radians, and the .Y property was the distance away from the origin. Polar Coordinates in other words.

Then its just a simple job of adding the each .X to the angle of the hand and drawing the resulting polygon. Simple and precise.

Now available!

http://www.vbforums.com/showthread.p...hreadid=305238

binaries only.

.Net only, also!

Quote:

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Originally posted by dglienna
.Net only, also!

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In order to elaborate.

This clock class is only available in .net format. This is because VB6 is a bit naff. :D