How can I detect collision among QPixmaps and QGraphicsItems objects
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Thanks it helps but implementation throws @In instantiation of 'class QForeachContainer<QPixmap [9]>':@
The main_target array, QPixmap and targetitems array, QGraphicsPixmapItem seem to not play well together. -
How did you define main_targets?
Is it
@
QVector<QPixmap> main_targets;
or
QPixmap main_targets[9];
@Qt specific keyword foreach works only with container classes like first definition. If you have second definition then you should use standard C++ for or while loop.
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Hi,
foreach must be used with a containers. A c array is not considered a container.
In your case you can use a classic for loop or change your array to a QList of QPixmap
Hope it helps
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Changing to containers I get the index is out of range error. Can I not assign each QPixmap an array value?
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If you use containers then you should use append() method to add pixmaps to your container.
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I thought the @QVector<QGraphicsPixmapItem*> targetItems;
foreach(QPixmap pix, main_targets) {
QGraphicsPixmapItem* item = QGraphicsPixmapItem(pix);
targetItems.append(item);
}@ takes each instance of the main_targets array, and creates QGraphicsPixmapItems of them. -
Could you show the code where you are getting "index is out of range" error.
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I pass the pmap to the MainTarget class by pointer, which was previously by reference. There isn't a specific line that the compiler is showing. It crashes on execution. I replaced main_targets[index] with targetItems since that should hold the QGraphicsPixmapItem items.
@void Dialog::setPixmaps()
{
//Targets are delivered every 1sec
Five_timer->start(1000);QList<QGraphicsPixmapItem*> targetItems; foreach(QPixmap pix, main_targets) { QGraphicsPixmapItem* p_item = new QGraphicsPixmapItem(pix); targetItems.append(p_item); } int StartY = 0; //Random starting Y point between -140 and -389 StartY = (qrand() % (-400 + 150) -140); index = (qrand() % 9); { if(index % 2 == 0) { //When even is selected start at far right pmap = new MainTargets(targetItems[index], 0); pmap->setPos(345,StartY); } else { //When odd is selected start at far left pmap = new MainTargets(targetItems[index], 1); pmap->setPos(-325,StartY); } } scene->addItem(pmap);
}@
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Does it always crash on the same place?
Try to step through the function using a debugger.What is the type of main_targets in line #9?
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QList<QPixmap> main_targets is the type.
Seems to fail at the QList::operator[].
That is why I think the main_target array seems to be the issue.
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How do you fill main_target?
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Guess that is where the problem is I thought the @ QList<QGraphicsPixmapItem*> targetItems;
foreach(QPixmap pix, main_targets) {
QGraphicsPixmapItem* p_item = new QGraphicsPixmapItem(pix);
targetItems.append(p_item);@ fills the main_target list. If not what is the purpose of this line? -
In this code you take the pixmaps from main_target and create qlist of qgraphicsitems.
So, the main_target must be populated by the qpixmaps before this code. -
@ main_targets[0] = QPixmap(":images/darkbluelogo.jpg");
main_targets[1] = QPixmap(":images/graylogo.jpg");
main_targets[2] = QPixmap(":images/lightbluelogo.jpg");
main_targets[3] = QPixmap(":images/lime.jpg");
main_targets[4] = QPixmap(":images/pink.jpg");
main_targets[5] = QPixmap(":images/purple.jpg");
main_targets[6] = QPixmap(":images/redlogo.jpg");
main_targets[7] = QPixmap(":images/yellow.jpg");
main_targets[8] = QPixmap(":images/brown.jpg");@The main_targets are created and stored in the constructor initially before anything is done. So the qlist should have 9 qpixmaps.
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If I'm not mistaken you need to use .append() method to add elements to the QList. QList::opeartor[] does not work for adding new elements.
EDIT: Yep, you have to use append() or operator+=() to extend a list "operator[]":http://qt-project.org/doc/qt-5/qlist.html#operator-5b-5d requires an index to be valid (0 <= i < qlist.size())
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Thank you finally have it switched over to QGraphicsPixmapItems. Now the initial problem and see if I can get the collision working.
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Ok the original problem of colliding the two objects. My thinking at the beginning of this post was to have something along the lines of:
@if(pellets->collidesWithItem(targets){
remove(pellets)
remove(targets)}@
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I wouldn't delete the items right away, but only hide them, and delete them later on. But otherwise, it might be something like this.
Have you taken a look at the Colliding Mice example?
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Yeah I've looked at that example a lot. Doesn't seem to be in the realm of what I'm trying to accomplish.
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So you have some QGraphicsItem subclass and come QGraphicsPixmap. You check whether they collide. That part you should be able to take from the example.
If they collide, you hide those items and add them to a list of items "to be deleted" (or "to be re-used", if you prefer).
You either clean up the list from time to time (using e.g. a timer), or you re-use the items in the list if you need to add a new item (which would be a performance optimization, since creating GraphicsItems isn't free).
Where specifically do you have problems?