Hud and QGraphicsView

Andrea Mugnaini

How to implement the hud (ie: life, high score, level,...), in a game where the qgraphicsview follows a qgraphicsitem of qgraphicscene?
I need to anchor a qgraphicstextitem (or label, ...) so that it does not scroll with the qgraphicscene.
Would make sense to anchor the hud to qgraphicsview?

Suggestions or thoughts?

Many thanks.

kkrzewniak

Have you tried using custom some widgets with the graphicsview as their parent. And than setting their positions in the graphicsviews resize event.

andre

Doesn't the QGraphicsItem::ItemIgnoresTransformations flag provide that functionality?

Andrea Mugnaini

If i add a qwidget on top of qgraphicsview, i note some problems with alpha channel of widget's background.

furthermore

if i set the flag of QGraphicsProxyWidget (got after calling addWidget on qgraphicscene) with ItemIgnoresTransformations, nothing happens.
...
A Solution could be: fix the qgraphicsview on qgraphicsscene, then scroll manually the content of qgraphicscene.

Andrea Mugnaini

Strange,
if i setViewport with QWidget instead QGLWidget, it works (I can see a correct blending between the transparencies of the backgrounds).
...

Hence, recapping:

I have a QWidget (my hud) with transparent background;
My hud is a son of QGraphicsView;
If the QGraphicsView has a viewport of type QWidget, i can see correct blending of backgrounds.
If the QGraphicsView has a viewport of type QGLWidget, i see a black background for my Hud.

Comments?

Many Thanks.

deimos

for transparencies in openGL I think you can try this:
@qgl=new QGLWidget(new QGLContext(QGLFormat(QGL::Rgba | QGL::DoubleBuffer | QGL::AlphaChannel | QGL::HasOverlay)));
setViewport(qgl);@

and to retrieve the coordinates to draw your HUD sticky to a position, you have to calculate the mapped position relatively to the current scene. For example, if you want to draw it at coords (10,10) of QGraphicsView widget:
@pos=mapToScene(10,10);
hud.setPos(pos);@

hope this help

Andrea Mugnaini

First of all, thanks for the support.

I tried the suggestion above but, nothing happens.
Hence, i invite you to see with your eyes the problem,
you can download this:
"TestHudView":https://sites.google.com/site/mugnaini81/TestHudView.zip?attredirects=0&d=1

you can try to uncomment(or hack) inside @void ZGraphicsView::Init()@

Many thanks.

deimos

I didn't know why a transparent widget over a openGL GraphicsView isn't transparent. I think some function like initGL and updateGL should be reimplemented correctly, but you can reimplement "QGraphicsView::drawForeground":http://doc.qt.nokia.com/latest/qgraphicsview.html#drawForeground to positioning the "QGraphicsProxyWidget *hud" when needed as follow

@void ZGraphicsView::drawForeground ( QPainter * painter, const QRectF & rect )
{
hud->setPos(mapToScene(100, 10));
}

void ZGraphicsView::Init()
{
//------------------- CHECK THIS! -------------------
// setViewport(new QWidget());
setViewport(new QGLWidget(new QGLContext(QGLFormat(QGL::Rgba | QGL::DoubleBuffer | QGL::AlphaChannel | QGL::HasOverlay))));
//---------------------------------------------------

// Hud Settings (on QGraphicsView)
QLabel* label = new QLabel("HUD!", 0);
label->setStyleSheet("QLabel{background: transparent; color: red; font: 40px;}");
label->setFixedSize(100, 44);
label->move(0, 0);

// Background settings (on QGraphicsScene)
ZGraphicsScene* scene = new ZGraphicsScene();
QGraphicsPixmapItem* myBackground = new QGraphicsPixmapItem(QPixmap(":/background.png"), 0);
scene->addItem(myBackground);
setScene(scene);
setFixedSize(myBackground->boundingRect().size().toSize());

hud = scene->addWidget(label);
hud->setPos(mapToScene(100, 10));

show();

}@

Andrea Mugnaini

[quote author="MarcoB" date="1297775701"] but you can reimplement "QGraphicsView::drawForeground":http://doc.qt.nokia.com/latest/qgraphicsview.html#drawForeground to positioning the "QGraphicsProxyWidget *hud" when needed as follow
[/quote]

The Test that i added above it isn't my true case.
In my case, i can't do it, because (for now) i have the QGraphicsView that scrolls a QGraphicsScene, so if i move my hud to fixed position, whenever drawForeground is executed, i see that my hud flickers with scrolling.

Many Thanks.

saddan

Hi,

Did you solve the transparency problem with widgets added to the scene?

Andrea Mugnaini

Yes, i solved this problem (more or less).
You can find my game here:
http://sites.google.com/site/mugnaini81/Psycho-naut_source_code_v016.zip

but, now i am using another kind of solution for the hud cause i stopped to use the qgraphicsview system.

Basically I am developing a 3D shoot' em up, using a QGLWidget with an hybrid system for the hud: ortographic projection+qfont+opengl commands.

Alain38

As I found this topic searching another similar problem, just a way to have a transparent widget on an OpenGL background:
@widget->setWindowOpacity(0.95);
widget->setAttribute(Qt::WA_TranslucentBackground);@

The opacity value is just to see what you put in the widget. The only forbidden value is 1.0.