Qt and OpenGl (I'm lost)

[anon789]

Sorry to bump this, I really need help figuring this out otherwise I can't even get started.

Maybe if you don't feel like answering my question, please reply with a link to some tutorial or example that would help me understand why my opengl calls are not working outside paintGL.

Sorry again for the bump and thanks in advance.

[JohannesMunk]

Hi!

To my knowledge that's exactly how it's supposed to work. Why do you want to mix philosophies here? paintGL is fine for pure raw openGL.

Use a widgets paintevent if you want to use QPainter. BTW: Qt's OpenGL QPainter implementation is quite good. So it might be a lot easier and more portable to use QPainter and use QGraphicsView with an OpenGL Viewport.

Have a look at this: http://www.qtcentre.org/threads/2999...ht=#post140754

Maybe you should describe what you want to do, and then we can find a solution.

Johannes

[anon789]

Hi JohannesMunk,

Basically I want to create an application to illustrate certain aspects of linear algebra : draw vectors, planes, vector/dot product, point closer to a line, etc. I am mostly doing this to learn, I love math et want to learn Qt and OpenGL to a higher level (this is the reason for mixing the philosophies).

I will have a look at the link you posted as soon as I get home and post back. Thanks a lot.

[JohannesMunk]

Ok! Then I would highly recommend to use the comfortable opengl wrapping that QPainter allows:

In another thread just yesterday I set up a simple OpenGL GraphicsView:

http://www.qtcentre.org/threads/3424...476#post158476

Instead of a button-widget you will add lots of custom QGraphicsItems for the different mathematical objects.

Use scene->addItem(new Vector(QVector3D(..)));

class Vector : public QGraphicsItem
{
public:
    Vector(QVector3D a);
    QRectF boundingRect() const{ return QRectF( ... ); }
 
    void paint(QPainter *painter, const QStyleOptionGraphicsItem *item, QWidget *widget)
    {
        painter->drawLine(.. );
    }
};

class Vector : public QGraphicsItem
{
public:
    Vector(QVector3D a);
    QRectF boundingRect() const{ return QRectF( ... ); }

    void paint(QPainter *painter, const QStyleOptionGraphicsItem *item, QWidget *widget)
    {
        painter->drawLine(.. );
    }
};

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Let me know if you run into more problems!

Joh