Hi all,

I am new to Tk, so please bear with me. I need someone better at math

than me to help me figure this out. I am drawing multiple arcs on the

same circle. All arcs start at 90 and have varying negative extents

(different colors, goes all the way around. Represents a microbial

genome). So now that my arcs are drawn, I would would like to draw a

line, 25 pixels long that starts on the circle at the endpoint of each

of the arcs, and looks like an extension of the radius extending above

the circle. Then I would like to print text at the end of this line. So

my question is how do I dynamically calculate the line coordinates?

Circle size is fixed, number of arcs and their extents are variable.

Code for drawing arc;

$x1,$y1 = 25

$x2,$y2 = 775

$xcenter = $x2/2 + $x1;

$ycenter = $y2/2 + $y1;

$canvas->createArc($x1,$y1,$x2,$y2,

-width=>10,

-outline=>$colors[$color],

-style=>'arc',

-start=>90,

-extent=>-$actual_angle,

-tags=>$myorfs{$key}[1]);

What I have so far to draw lines:

$xstart = (cos($current_arclength)*$radius+$xcenter) /10;

$ystart = (sin($current_arclength)*$radius+$ycenter) /10;

$canvas->createLine($xstart+$xcenter,

$ystart+$ycenter,

$xstart+($xstart*0.01)+$xcenter,

$ystart+($ystart*0.01)+$ycenter);

This draws an oval of lines, inside the orginal circle, with the line

length having sin periodicity around the circle. Can anyone improve my

math so that I can get the lines placed properly with the proper length?

Please email me directly as well as respond to the list. Thanks so much

in advance.

--Math Challenged Mark

Ma**********@bayer.com