Symbol line direction in curved polygon

[Barry Kelly]

I am modifying a GS hedge object to make it a little more useful for myself.
I want to add a ‘grass’ symbol line type to the perimeter in plan to make it look a little more hedgy.
This works fine when the perimeter is closed on a curved hedge.
But as soon as I use the masking code to turn off the line for one edge the line on the inside curve inverts for some reason.
There is no problem at all for a straight hedge – only when the polygon has a curve it seems.

Here is the code used for the polygon.

rad = 1.000
breit = 0.500
wink = 90

end_1_swch = 1
end_2_swch = 0	 !!change to 1 to close polygon

poly2_b 7,1+2+4,gs_fill_pen,gs_back_pen,
	rad,0,end_1_swch,
	rad+breit,0,1,
	0,0,900,
	(rad+breit)*cos(wink),(rad+breit)*sin(wink),3000+end_2_swch,
	rad*cos(wink),rad*sin(wink),1,
	0,0,900,
	rad, 0,3001

Reversing the polygon doesn’t help either.

add2 1.5, 0
poly2_b 7,1+2+4,gs_fill_pen,gs_back_pen,
	rad,0,1,
	0,0,900,
	rad*cos(wink),rad*sin(wink),3000+end_2_swch,
	(rad+breit)*cos(wink),(rad+breit)*sin(wink),1,
	0,0,900,
	rad+breit,0,3000+end_1_swch,
	rad, 0,1
del 1

Even using ARC2 won’t help as you can’t reverse the direction of the line and can’t use a negative radius.

Is this a bug (and if so can it be fixed)?
Any ideas for a solution that doesn’t involve creating a new symbol line type that is reversed in the y direction and then using two polygons with various edges hidden or not?

I am guessing that the positive y portion of a symbol line will always project towards the centre of an arc unless in a closed polygon with visible edges in which the direction can be reversed depending on the order of node scripting.

Barry.

Attachments:

1. 

   invert_line.jpg
   

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