c++ - 如何检测像素图边缘透明的两个 QGraphicsPixmapItem 之间的碰撞？

Question

我有两个QGraphicsPixmapItem，它们的边缘都是透明的，而且它们不是矩形。当我尝试使用 QGraphicsItem::collidingItems() 时，它只检查它们的边界矩形是否发生碰撞。有没有办法只检测非透明部分的碰撞？

Answer 1

您必须将形状模式设置为 QGraphicsPixmapItem::HeuristicMaskShape :

QGraphicsPixmapItem::HeuristicMaskShape

The shape is determine by calling QPixmap::createHeuristicMask(). The performance and memory consumption is similar to MaskShape

---

your_item->setShapeMode(QGraphicsPixmapItem::HeuristicMaskShape);

例子:

main.cpp

#include <QApplication>
#include <QGraphicsPixmapItem>
#include <QGraphicsView>

#include <QDebug>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QGraphicsView w;
    QGraphicsScene *scene = new QGraphicsScene;
    w.setScene(scene);

    QList<QGraphicsPixmapItem *> items;

    for(const QString & filename: {":/character.png", ":/owl.png"}){
        QGraphicsPixmapItem *item = scene->addPixmap(QPixmap(filename));
        item->setShapeMode(QGraphicsPixmapItem::HeuristicMaskShape);
        item->setFlag(QGraphicsItem::ItemIsMovable, true);
        item->setFlag(QGraphicsItem::ItemIsSelectable, true);
        items<<item;
    }

    items[1]->setPos(50, 22);
    if(items[0]->collidingItems().isEmpty())
        qDebug()<<"there is no intersection";
    w.show();
    return a.exec();
}

输出:

there is no intersection

完整的例子可以在下面的link中找到