So I found this example: https://github.com/GNOME/gtkmm/blob/master/demos/gtk-demo/example_glarea.cc And it has #include <epoxy/gl.h> , and I thought, "what is that?" So I found this: https://github.com/anholt/libepoxy And, gee, it just works! I'm not sure if this is enough, becase epoxy_gl_version() returns 0, but the glArea->get_required_version() returns 4.5. I'll pretend it doesn't matter for now and bug someone (else?) later if I'm again at my wit's end. On Sun, 2021-04-11 at 01:52 +0000, JLM via gtkmm-list wrote:
I am trying to make use of OpenGL 4.5 in a gtkGlArea. The code below
works. However, I have the OpenGL Programming Guide Ninth Edition, and
it uses this instead of glClearColor:
static const float black[] = { 0.0, 0.0, 0.0, 0.0 };
glClearBufferfv(GL_COLOR, 0, black);
When I try to use that, the compile doesn't find it:
gtkgl.cpp:32:5: error: 'glClearBufferfv' was not declared in this
scope; did you mean 'glReadBuffer'?
32 | glClearBufferfv(GL_COLOR, 0, black);
I also tried #include <GL/glext.h> but that didn't help.
So then I thought maybe I need to make use of GLEW. When I #include
<GL/glew.h>, that compiles at least. But, then I can't run GLEW's
setup:
GLenum glewError = glewInit();
if(glewError != GLEW_OK)
{
std::cerr << "Error: " << glewGetErrorString(glewError) <<
std::endl;
}
When I run, it always says:
Error: Missing GL version
So then I found the gtkGlArea method, set_required_version, and set it:
gl
Area->set_required_version(4, 5);
But that still didn't help. So then I thought maybe the GLEW init needs
to be in the on_realize() section, as I saw that this is where you put
OpenGL init stuff, but that still didn't work.
So, what do I need to #include? Should I make use of GLEW, or does
GTK(MM) do everything necessary to get OpenGL already? Are there any
tutorials or examples? Most everything I find is for OpenGL 3.3, but I
don't know how to align that with the book I've got.
Thanks for any help you can provide.
#include <gtkmm.h>
#include <iostream>
#include <GL/gl.h>
#include <GL/glu.h>
Gtk::Window* pDialog = nullptr;
static
void on_button_clicked()
{
if(pDialog)
pDialog->hide(); //hide() will cause main::run() to end.
}
bool glRender(const Glib::RefPtr<Gdk::GLContext>&)
{
glClearColor(1.0f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
return true;
}
int main (int argc, char **argv)
{
auto app = Gtk::App
lication::create(argc, argv, "org.test");
//Load the GtkBuilder file and instantiate its widgets:
auto refBuilder = Gtk::Builder::create();
try
{
refBuilder->add_from_file("glarea.glade");
}
catch(const Glib::FileError& ex)
{
std::cerr << "FileError: " << ex.what() << std::endl;
return 1;
}
catch(const Glib::MarkupError& ex)
{
std::cerr << "MarkupError: " << ex.what() << std::endl;
return 1;
}
catch(const Gtk::BuilderError& ex)
{
std::cerr << "BuilderError: " << ex.what() << std::endl;
return 1;
}
//Get the GtkBuilder-instantiated Dialog:
refBuilder->get_widget("Window", pDialog);
if(pDialog)
{
//Get the GtkBuilder-instantiated Button, and connect a signal
handler:
Gtk::MenuItem* pButton = nullptr;
refBuilder->get_widget("quitMenuItem", pButton);
if(pButton)
{
pButton->signa
l_activate().connect( sigc::ptr_fun(on_button_clicked) );
}
Gtk::GLArea* glArea = nullptr;
refBuilder->get_widget("glarea", glArea);
if(glArea)
{
glArea->signal_render().connect(sigc::ptr_fun(glRender) );
}
app->run(*pDialog);
}
delete pDialog;
return 0;
}
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