const startValue := 30
const maxValue := 70
const incrementAmount := 0.1
const maxDist := 700

procedure DrawLine (x, y : real, angle : real, dist : real, inc : real)
    Draw.ThickLine (round (x), round (y), round (x + cosd (angle) * dist), round (y + sind (angle) * dist), 1, white)
    if dist > maxDist then
        return
    end if
    DrawLine (round (x + cosd (angle) * dist), round (y + sind (angle) * dist), angle + inc, dist + 1, inc)
end DrawLine

View.Set ('graphics:500,500')
View.Set ('offscreenonly')
View.Set ('nobuttonbar')
View.Set ('position:centre;centre')

Text.ColourBack (black)
cls
var a : real := startValue
loop
    a += incrementAmount
    if a > maxValue then
        a := startValue
    end if

    DrawLine (maxx div 2, maxy div 2, 0, 0, a)
    View.Update
    Time.DelaySinceLast (50)
    cls
end loop

View.Set("graphics:300;200, nobuttonbar, noecho")