# Pie Chart Algorithms?

Sivakatirswami katir at hindu.org
Wed Mar 1 14:47:43 EST 2006

```Doing that only increased the size the arc line that was drawn. The
two radius lines from the center out to the end of the arc, forming
the pie did not always appear, sometimes yes, sometimes no...  but by
setting the opaque on create oval to true then the background color
appears whether or not the radius lines show or not.. so that works.
I have to test some more. possible the opaque property is turning the
radius lines off and on as well...

Now my next challenge is to get a list of points on the circumference
of any circle.  I checked the mailing lists and can't find the
algorithm or sample script that would do this. If anyone has the
"professional" algorithm to do this please do post it... /H's chart
stack is protected...

I'm working with setting a single radius at 3 o'clock and rotating
this through 90 degrees using "revRotatePoly" and logging the end
point on 90 iterations of 1 degree. And then I think I can use the
I think this must be  horrible hack and that someone has a much
"cleaner" way to get this list of pioints -- some very "cool" math
function...

ON mouseUp
put (the right of grc "BaseCircle" & "," & the height of grc
"BaseCircle"/2+the top of grc "BaseCircle") into tVariablePosition
put 1 into tIncrement
set the points of grc "Line" to (the loc of grc "baseCircle",
tVariablePosition)
put line 2 of the points of grc "line" into tLoc
repeat 90 times
put tLoc & cr after fld "props" ## log the end point on each
iteration
set the points of grc "Line" to (the loc of grc "baseCircle",
tVariablePosition)
revRotatePoly the long id  of  grc "line",tIncrement
put tIncrement +1 into tIncrement
put line 2 of the points of grc "line" into tLoc
set the loc of grc "littleBall" to tLoc
end repeat

END mouseup

result

628,364 (3 o'clock on this particular circle)
626,368
626,372
626,376
626,380
626,384
626,390
etc (90 lines of such points... from 3 o'clock to 6 o'clock --
straight down)

OK set this aside for a while... it's something to work on when the
brain needs a break from "real" work on a rainy day off...

Hopefully someone will come to my rescue by the time I try to carry
this forward.

And a related issue: move grc "ball" to the points of grc "oval"
doesn't do anything... oval's don't have any points (?) doesn't make
sense to me: any line object on a screen is a series of pixels... how
can it not have points?

Sivakatirswami

On Mar 01, 2006, at 7:33 AM, Devin Asay wrote:

>
> On Feb 28, 2006, at 3:35 PM, Sivakatirswami wrote:
>>
>
>> The only caveat I discovered that there was some unknown
>> "condition" wherein the arc is drawn sans the radius lines... i.e
>> you get just a curved line..a simple arc...   but, if I draw an
>> oval manually and set it's arc angle one gets a complete "pie" cut
>> polygon shape. And now my script only creates the full pie shape..
>>
>> Can anyone tell us what determines whether full pie piece is drawn
>> or just the arc without radius lines?
>
> Don't you just need to set the lineSize of the oval graphic to > 0 ?
>
> Devin
>
> Devin Asay
> Humanities Technology and Research Support Center
> Brigham Young University
>
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