bool QTessellatorPrivate::edgeInChain(Intersection i, int edge)
{
int end = i.edge;
while (1) {
if (i.edge == edge)
return true;
IntersectionLink l = intersections.value(i);
if (l.next == end)
break;
Q_ASSERT(l.next != -1);
Q_ASSERT(l.prev != -1);
Intersection i2 = i;
i2.edge = l.next;
#ifndef QT_NO_DEBUG
IntersectionLink l2 = intersections.value(i2);
Q_ASSERT(l2.next != -1);
Q_ASSERT(l2.prev != -1);
Q_ASSERT(l.next == i2.edge);
Q_ASSERT(l2.prev == i.edge);
#endif
i = i2;
}
return false;
}
void QTessellatorPrivate::addIntersection(const Edge *e1, const Edge *e2)
{
const IntersectionLink emptyLink = {-1, -1};
int next = vertices.nextPos(vertices[e1->edge]);
if (e2->edge == next)
return;
int prev = vertices.prevPos(vertices[e1->edge]);
if (e2->edge == prev)
return;
Q27Dot5 yi;
bool det_positive;
bool isect = e1->intersect(*e2, &yi, &det_positive);
QDEBUG("checking edges %d and %d", e1->edge, e2->edge);
if (!isect) {
QDEBUG() << " no intersection";
return;
}
// don't emit an intersection if it's at the start of a line segment or above us
if (yi <= y) {
if (!det_positive)
return;
QDEBUG() << " ----->>>>>> WRONG ORDER!";
yi = y;
}
QDEBUG() << " between edges " << e1->edge << "and" << e2->edge << "at point ("
<< Q27Dot5ToDouble(yi) << ')';
Intersection i1;
i1.y = yi;
i1.edge = e1->edge;
IntersectionLink link1 = intersections.value(i1, emptyLink);
Intersection i2;
i2.y = yi;
i2.edge = e2->edge;
IntersectionLink link2 = intersections.value(i2, emptyLink);
// new pair of edges
if (link1.next == -1 && link2.next == -1) {
link1.next = link1.prev = i2.edge;
link2.next = link2.prev = i1.edge;
} else if (link1.next == i2.edge || link1.prev == i2.edge
|| link2.next == i1.edge || link2.prev == i1.edge) {
#ifdef DEBUG
checkLinkChain(intersections, i1);
checkLinkChain(intersections, i2);
Q_ASSERT(edgeInChain(i1, i2.edge));
#endif
return;
} else if (link1.next == -1 || link2.next == -1) {
if (link2.next == -1) {
qSwap(i1, i2);
qSwap(link1, link2);
}
Q_ASSERT(link1.next == -1);
#ifdef DEBUG
checkLinkChain(intersections, i2);
#endif
// only i2 in list
link1.next = i2.edge;
link1.prev = link2.prev;
link2.prev = i1.edge;
Intersection other;
other.y = yi;
other.edge = link1.prev;
IntersectionLink link = intersections.value(other, emptyLink);
Q_ASSERT(link.next == i2.edge);
Q_ASSERT(link.prev != -1);
link.next = i1.edge;
intersections.insert(other, link);
} else {
bool connected = edgeInChain(i1, i2.edge);
if (connected)
return;
#ifdef DEBUG
checkLinkChain(intersections, i1);
checkLinkChain(intersections, i2);
#endif
// both already in some list. Have to make sure they are connected
// this can be done by cutting open the ring(s) after the two eges and
// connecting them again
Intersection other1;
other1.y = yi;
other1.edge = link1.next;
IntersectionLink linko1 = intersections.value(other1, emptyLink);
Intersection other2;
other2.y = yi;
other2.edge = link2.next;
IntersectionLink linko2 = intersections.value(other2, emptyLink);
linko1.prev = i2.edge;
link2.next = other1.edge;
linko2.prev = i1.edge;
link1.next = other2.edge;
intersections.insert(other1, linko1);
intersections.insert(other2, linko2);
}
intersections.insert(i1, link1);
intersections.insert(i2, link2);
#ifdef DEBUG
checkLinkChain(intersections, i1);
checkLinkChain(intersections, i2);
Q_ASSERT(edgeInChain(i1, i2.edge));
#endif
return;
}