Deriving an angle from three points

Colin Holgate coiin at verizon.net
Wed Dec 16 11:01:42 EST 2009

```On Dec 16, 2009, at 1:21 AM, Mark Swindell wrote:

> 40,116
> 98,186
> 132,118
>
> How would one determine the angle created from three points, such as those above?

All of the suggested scripts seem quite long. Try putting this script into three buttons. The script uses the Other Mark's way of dragging the button around (and it doesn't hilite the button as he claims):

on mouseDown
repeat until the mouse is up with messages
set the loc of me to the mouseLoc
wait 0 millisecs with messages
end repeat
put 180 - angler(loc of btn 1,loc of btn 2,loc of btn 3)/pi*180
end mouseDown
function angler p1, p2, p3
put atan2(item 2 of p2-item 2 of p1,item 1 of p2 - item 1 of p1) into angle1
put atan2(item 2 of p3-item 2 of p2,item 1 of p3 - item 1 of p2) into angle2
return abs(angle2-angle1)
end angler

The bit that calculates the angle could be done in a single line:

put 180 - (atan2(item 2 of p3-item 2 of p2,item 1 of p3 - item 1 of p2)-atan2(item 2 of p2-item 2 of p1,item 1 of p2 - item 1 of p1))/pi*180

```