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[smlnj] View of /eXene/releases/release-110.77/graph-util/poly.sml
 [smlnj] / eXene / releases / release-110.77 / graph-util / poly.sml # View of /eXene/releases/release-110.77/graph-util/poly.sml

Fri Aug 22 21:39:51 2014 UTC (4 years, 10 months ago) by jhr
File size: 884 byte(s)
`Release 110.77`
```    fun polygonRegion (l as [_,_,_], fill_rule) = poly(l,fill_rule)
| polygonRegion (l as [a,b,c,d], fill_rule) =
if isRect(a,b,c,d) then mkRect(a,b,c,d) else poly(l,fill_rule)
| polygonRegion (l as [a,b,c,d,e], fill_rule) = poly(l,fill_rule)
if a = e andalso isRect(a,b,c,d) then mkRect(a,b,c,d) else poly(l,fill_rule)
| polygonRegion (l as (_::_::_::_), fill_rule) = poly(l,fill_rule)
| polygonRegion _ = zeroRegion

fun isRect(PT{x=ax,y=ay},PT{x=bx,y=by},PT{x=cx,y=cy},PT{x=dx,y=dy}) =
((ay = by andalso bx = cx andalso cy = dy andalso dx = ax) orelse
(ax = bx andalso by = cy andalso cx = dx andalso dy = ay)) andalso
let
val x1 = min(ax, cx)
val y1 = min(ay, cy)
val x2 = max(ax, cx)
val y2 = max(ay, cy)
in x1 <> x2 andalso y1 <> yw end

```