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Comment:In the GeoPoly documentation, mention that geopoly_ccw() can be used to correct vertex order after geopoly_xform().
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User & Date: drh 2018-11-24 20:58:44
Context
2018-11-26
12:01
Merge typo fix from the 3.25 branch. check-in: 121aeee579 user: drh tags: trunk
2018-11-24
20:58
In the GeoPoly documentation, mention that geopoly_ccw() can be used to correct vertex order after geopoly_xform(). check-in: bfc897c9c0 user: drh tags: trunk
20:24
Minor enhancements and updates to various documents. check-in: 9e12c649c9 user: drh tags: trunk
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Changes to pages/geopoly.in.

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<p>
To rotate a polygon by R radians around the point 0, 0:

<codeblock>
geopoly_xform($polygon, cos($R), sin($R), -sin($R), cos($R), 0, 0)
</codeblock>









<tcl>hd_fragment regpoly geopoly_regular</tcl>
<h2>The geopoly_regular(X,Y,R,N) Function</h2>

<p>
The geopoly_regular(X,Y,R,N) function returns a convex, simple, regular,
equilateral, equiangular polygon with N sides, centered at X,Y, and with







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<p>
To rotate a polygon by R radians around the point 0, 0:

<codeblock>
geopoly_xform($polygon, cos($R), sin($R), -sin($R), cos($R), 0, 0)
</codeblock>

<p>
Note that a transformation that flips the polygon might cause the
order of vertexes to be reversed.  In other words, the transformation
might cause the vertexes to circulate in clockwise order instead of
counter-clockwise.  This can be corrected by sending the result
through the [geopoly_ccw()] function after transformation.


<tcl>hd_fragment regpoly geopoly_regular</tcl>
<h2>The geopoly_regular(X,Y,R,N) Function</h2>

<p>
The geopoly_regular(X,Y,R,N) function returns a convex, simple, regular,
equilateral, equiangular polygon with N sides, centered at X,Y, and with