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poly2d/p2d_attrib.c (angle_3): don't divide by zero ...

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This broke p2d_is_cw which in turn tripped
CGAL::create_interior_skeleton_and_offset_polygons_with_holes_2
with the infamous

terminate called after throwing an instance of 'CGAL::Assertion_exception'
  what():  CGAL ERROR: assertion violation!
Expr: lParent
File: /usr/include/CGAL/arrange_offset_polygons_2.h
Line: 94
This commit is contained in:
Werner Almesberger 2015-01-18 20:27:26 -03:00
parent 05d3d50421
commit 7ca942d0e9
1 changed files with 6 additions and 2 deletions
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8
poly2d/p2d_attrib.c
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@ -28,19 +28,23 @@ static double angle_3(const struct v2d *a, const struct v2d *b,
{ {
double ax, ay, bx, by; double ax, ay, bx, by;
double aa, bb; double aa, bb;
double angle; double cross, angle;
ax = b->x - a->x; ax = b->x - a->x;
ay = b->y - a->y; ay = b->y - a->y;
bx = c->x - b->x; bx = c->x - b->x;
by = c->y - b->y; by = c->y - b->y;
cross = ax * by - ay * bx;
if (!cross)
return 0;
aa = hypot(ax, ay); aa = hypot(ax, ay);
bb = hypot(bx, by); bb = hypot(bx, by);
angle = acos((ax * bx + ay * by) / aa / bb) / M_PI * 180.0; angle = acos((ax * bx + ay * by) / aa / bb) / M_PI * 180.0;
return ax * by - ay * bx >= 0 ? angle : -angle; return cross >= 0 ? angle : -angle;
} }
/* /*