1. Unit vector help, please
I'd like to draw a unit arrow to point from source to target. I've got
the following routine that works but seems overcomplicated to me. Can
it be simplified?
procedure drawArrow( sequence source, sequence target )
integer x1, y1, x2, y2, xdiff
atom slope, ang
setPenColor( Win, Black )
xdiff = target[X]-source[X]
if xdiff then -- no worries about divide by zero
slope = (target[Y]-source[Y])/xdiff
ang = arctan( slope )
x1 = floor(20*cos(ang))
y1 = floor(20*sin(ang))
x2 = -x1
y2 = -y1
drawLine( Win, 30+x1, 30+y1, 30+x2, 30+y2 )
if source[X] > target[X] then -- simple arrow head for now
drawEllipse( Win, w32True, 27+x2, 27+y2, x2+33, y2+33 )
else
drawEllipse( Win, w32True, 27+x1, 27+y1, x1+33, y1+33 )
end if
else -- direction is up or down
drawLine( Win, 30, 10, 30, 50 )
if source[Y] > target[Y] then -- simple arrow head for now
drawEllipse( Win, w32True, 27, 7, 33, 13 )
else
drawEllipse( Win, w32True, 27, 47, 33, 53 )
end if
end if
end procedure
Thanks in advance,
-- Brian
