INT32 BOCTX::EVENT::Compare(const EVENT &a, const EVENT &b)
{
assert(INT20_MIN <= a.x and a.x <= INT20_MAX);
assert(INT20_MIN <= a.y and a.y <= INT20_MAX);
assert(INT20_MIN <= b.x and b.x <= INT20_MAX);
assert(INT20_MIN <= b.y and b.y <= INT20_MAX);
if (a.x != b.x)
return a.x - b.x;
TYPE aType = a.GetType();
TYPE bType = b.GetType();
int asx, asy, bsx, bsy;
if (aType == X)
asx = a.GetSignX(), asy = a.GetSignY();
else
asx = asy = 0;
if (bType == X)
bsx = b.GetSignX(), bsy = b.GetSignY();
else
bsx = bsy = 0;
if (asx != bsx)
return asx - bsx;
if (a.y != b.y)
return a.y - b.y;
if (asy != bsy)
return asy - bsy;
if (aType != bType)
return aType - bType;
return a.id - b.id;
} // EVENT::Compare
void BOCTX::HandleEvent(EVENT & event)
{
switch (event.GetType())
{
case EVENT::E:
{
SEGM2 * sn = event.e.s->n;
SEGM2 * sp = event.e.s->p;
// untie segment
m_S.erase(SEGM_LIST::iterator(event.e.s));
CheckForCross(sp, sn);
} break;
case EVENT::S:
InsMainList(event.s.s);
CheckForCross(event.s.s, event.s.s->n);
CheckForCross(event.s.s->p, event.s.s);
break;
case EVENT::X:
{
if (event.c.s0->n != event.c.s1)
return; // ignore crossing event in case of non-adjacent segments
SEGM_LIST::iterator s0(event.c.s0), s1(event.c.s1);
// swap segments
assert(s0->n == &*s1 and s1->p == &*s0);
// untie s0
m_S.erase(s1);
m_S.insert(s0, *s1);
CheckForCross(s1->p, &*s1);
CheckForCross(&*s0, s0->n);
} break;
}
} // BOCTX::HandleEvent
