Qt isn't generating .h and .cpp files for QOpenGLWidget

stevereine

Thank you for the quick response! When I do the promotion, I see that it calls out a .h and a .cpp file to match my class name. To me that implies that it was generating these files, not just telling me what the file names should be. Thank you for your explanation. I thought that I did see somewhere where you could generate these files from the .ui file.

I have gone through that example code. Among many issues that I have found with it (I needed to add #include files, some of the variables, such as m_projection aren't even defined) it seems that the definition and the implementation of the constructor for MyGLWidget don't match. I get an error that says "out-of-line definition of 'MyGLWidget' does not match any declaration in 'MyGLWidget' ". Also, I believe the line in the main function should read 'MyGLWidget widget', not MyWidget widget'.

mrjj

@stevereine
Hi
The promotion dialog asked what Class to "promote to" and in which .h file it can find that class. But i can see if you are not sure what that features does it could look like it asked what to call it and where to put it :)

Yes you are right the class is called MyGLWidget so main.cpp is wrong. Good catch.

Did you fix the constructor error ?

stevereine

I have not been able to solve the constructor problem. I'll be honest with you, I'm a decent C++ guy but some of the nomenclature I see around contructors does confuse me. There might be something very obvious here that I don't understand. Here is the definition and the implementation. I didn't change anything, just cut and pasted from the example code.

definition:

public:
MyGLWidget(QWidget *parent) : QOpenGLWidget(parent) { }

implementation:

MyGLWidget::MyGLWidget()
: m_program(0), m_shader(0), m_texture(0)
{
// No OpenGL resource initialization is done here.
}

The brackets at the end of the implementation don't look right to me. I did try removing them, but just got different error.

thank you again!

mrjj

@stevereine
It seems you have 2 constructors
one that is fully defined in .h
the
MyGLWidget(QWidget *parent) : QOpenGLWidget(parent) { }

And then in .cpp you have another one that has no definition in .h and i think thats
what the "out of bounds " was talking about.

what about just doing
MyGLWidget(QWidget *parent) : m_program(0), m_shader(0), m_texture(0), QOpenGLWidget(parent) { }

and get rid of
MyGLWidget::MyGLWidget()
: m_program(0), m_shader(0), m_texture(0)
{
// No OpenGL resource initialization is done here.
}

as that takes no parent which we want for a QWidget so we would not use this anyway.

update:
maybe do it right so its
.h
MyGLWidget(QWidget *parent);
and .cpp
MyGLWidget::MyGLWidget(QWidget *parent) : m_program(0), m_shader(0), m_texture(0), QOpenGLWidget(parent) { }

stevereine

I'm one step ahead of you. I did try this earlier. When I comment out what you suggest, I get the following errors;

definition of implicitly declared destructor

no matching constructor for initialization of 'MyGLWidget'

MyGLWidget: no appropriate default constructor available

To fix at least part of this, I tried commenting out the destructor. Note I'm pasting the destructor from the example code here as well.

MyGLWidget::~MyGLWidget()
{
// Make sure the context is current and then explicitly
// destroy all underlying OpenGL resources.
makeCurrent();

delete m_texture;
delete m_shader;
delete m_program;

m_vbo.destroy();
m_vao.destroy();

doneCurrent();

}

When I comment out the destructor, I am left with two errors. I think it's really one error, both related to the constructor. Here are the errors:

error: no matching constructor for initialization of 'MyGLWidget'

error: C2512: 'MyGLWidget': no appropriate default constructor available

Regardless, I think we are close to solving this.

mrjj

@stevereine
Hi
"MyGLWidget: no appropriate default constructor available"
Sounds to me like you create one without giving it a parent?
like
MyGLWidget widget;
so fix is to do
MyGLWidget widget(nullptr);
(not giving it a parent will make it a window but i guess that is fine)
I assume its still the same main as in example ?

stevereine

One more comment, it doesn't seem like it's recognizing that line of code as a constructor:

public:
MyGLWidget(QWidget *parent) : QOpenGLWidget(parent) {}

mrjj

@stevereine
The : QOpenGLWidget(parent) should go to .cpp
as it dont like it in .h

so .h
MyGLWidget(QWidget *parent);
and in cpp
MyGLWidget::MyGLWidget(QWidget *parent) : QOpenGLWidget(parent) {

}

stevereine

Yes! That worked. It makes sense, but I never would have figured out by myself. I can now initialize the background to whichever color I want.

I've moved on now to adding the shaders and the init code for the shaders, getting an assert error when using;

attributeLocation("posAttr");m_posAttr = m_program->attributeLocation("posAttr");

The problem that I started this thread with is solved. Should I start a new query for this new assert error?

mrjj

@stevereine
Hi
Well i also forgot it has to be .cpp for the ctor initialiser list. 😋

I would make this as solved and open a new one for the shader issue simply
to make sure people see the actually issue right away.

stevereine

will do, thank you!