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# Example Script

Below is the text of a script which will generate a spiral object, provided as an example.

```# Example script to produce a spiral on the current layer
#
# solicit geometrical info from user
num = AskReal("Number of turns? ", "1")
if (num < 0 | num > 100)
ShowPrompt("Bad input (< 0 or > 100) for turns: ", num)
Exit()
end
width = AskReal("Width of spiral path? ", "4")
if (width < 0)
ShowPrompt("Bad input (< 0) for width: ", width)
Exit()
end
if (rmin < width/2)
Exit()
end
if (spa < width)
ShowPrompt("Bad input (< width) for pitch: ", pitch)
Exit()
end
nums = AskReal("Edges per 360 degrees? ", "50")
if (nums < 3 | nums > 90)
ShowPrompt("Bad input (< 3 or > 90) for edge count: ", nums)
Exit()
end

# initialize
width = width/2
dth = 2*pi/nums
n = nums*num + 1
i = 0
theta = 0

# there is an internal limit of 2000 polygon vertices
nverts = 2*n + 1
if (nverts > 2000)
ShowPrompt("Sorry, resulting polygon would have too many vertices.")
Exit()
end

# allocate array, size 2*nverts
array[4000] = 0

l = 4*n
j = 0

# fill in the array
while (i < n)
r = rmin + theta*spa/(2*pi)
x = (r-width)*cos(theta)
y = (r-width)*sin(theta)
array[j] = x
array[j+1] = y
x = (r+width)*cos(theta)
y = (r+width)*sin(theta)
array[l-j-2] = x
array[l-j-1] = y
j = j + 2
i = i + 1
theta = theta + dth
end

# close the path, necessary for polygon
array[l] = array[0]
array[l+1] = array[1]

# get the location for the spiral and transform array
ShowPrompt("Point to locate center of spiral")
xy[2]
PushGhost(array, nverts)
ShowGhost(8)
if !Point(xy)
Exit()
end
ShowGhost(0)
PopGhost()

i = 0
j = 0
while (i < nverts)
array[j] = array[j] + xy[0]
array[j+1] = array[j+1] + xy[1]
i = i + 1
j = j + 2
end

# create the polygon
drc = DRCstate(0)
Polygon(nverts, array)
Commit()
DRCstate(drc)
ShowPrompt("Info: spiral not drc'ed.  Drc takes a long time for these objects.")

#done
```

Stephen R. Whiteley 2012-04-01