Question

rel=“nofollow”>QPolygonF有办法与其他QPolygon公司结盟、交叉和分离但我需要与QLineF进行交叉测试。这似乎从APIC中消失。

我可以这样说:

if (polygon .containsPoint (line .p1 ()) != polygon .containsPoint (line .p2 ())
    return true;

QPointF a = polygon .back ();
foreach (QPointF b, polygon)
{
    if (QLineF :: BoundedIntersection == line .intersect (QPointF (a, b))
       return true;
    a = b;
}

return false;

在上述情况下,可能有一些数字或边错,因此我不是这样。

Is there a provided method somewhere in the Qt API that I can t see?

Answer 1

不幸的是,答案是“否”。

Answer 2

执行QPolygonF:摘录如下:

QPainterPath subject; subject.addPolygon(*this);
QPainterPath clip; clip.addPolygon(r);

return subject.intersected(clip).toFillPolygon();

i.e. QPolygonF uses QPainterPath methods to do the intersections. So you could do:

make a QPainterPath from the lines of the polygon
make a QPainterPath from your line
intersect them
check the result with isEmpty()
get the intersection point with boundingRect()

I DID NOT TRY THIS! 你们必须检查此事。我不敢肯定,在数字稳定和业绩方面,这比你的解决办法好,因此,你应写一些测试。

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