Merge pull request #29 from mindbrix/useInCircle
Use inCircle()
diff --git a/Source/geom.c b/Source/geom.c
index 97a5046..6600554 100755
--- a/Source/geom.c
+++ b/Source/geom.c
@@ -260,30 +260,34 @@
v->t = Interpolate( z1, o2->t, z2, d2->t );
}
}
-
-/*
- Calculate the angle between v1-v2 and v1-v0
- */
-TESSreal calcAngle( TESSvertex *v0, TESSvertex *v1, TESSvertex *v2 )
-{
- TESSreal num, den, ax, ay, bx, by;
- ax = v2->s - v1->s;
- ay = v2->t - v1->t;
- bx = v0->s - v1->s;
- by = v0->t - v1->t;
- num = ax * bx + ay * by;
- den = sqrt( ax * ax + ay * ay ) * sqrt( bx * bx + by * by );
- if ( den > 0.0 ) num /= den;
- if ( num < -1.0 ) num = -1.0;
- if ( num > 1.0 ) num = 1.0;
- return acos( num );
-}
+
+TESSreal inCircle( TESSvertex *v, TESSvertex *v0, TESSvertex *v1, TESSvertex *v2 ) {
+ TESSreal adx, ady, bdx, bdy, cdx, cdy;
+ TESSreal abdet, bcdet, cadet;
+ TESSreal alift, blift, clift;
+
+ adx = v0->s - v->s;
+ ady = v0->t - v->t;
+ bdx = v1->s - v->s;
+ bdy = v1->t - v->t;
+ cdx = v2->s - v->s;
+ cdy = v2->t - v->t;
+
+ abdet = adx * bdy - bdx * ady;
+ bcdet = bdx * cdy - cdx * bdy;
+ cadet = cdx * ady - adx * cdy;
+
+ alift = adx * adx + ady * ady;
+ blift = bdx * bdx + bdy * bdy;
+ clift = cdx * cdx + cdy * cdy;
+
+ return alift * bcdet + blift * cadet + clift * abdet;
+}
/*
Returns 1 is edge is locally delaunay
*/
int tesedgeIsLocallyDelaunay( TESShalfEdge *e )
-{
- return (calcAngle(e->Lnext->Org, e->Lnext->Lnext->Org, e->Org) +
- calcAngle(e->Sym->Lnext->Org, e->Sym->Lnext->Lnext->Org, e->Sym->Org)) < (M_PI + 0.01);
+{
+ return inCircle(e->Sym->Lnext->Lnext->Org, e->Lnext->Org, e->Lnext->Lnext->Org, e->Org) < 0;
}
