View Full Version : GUI with OpenGL

December 30th, 2008, 10:28 AM
I want GUI and OpenGL, and I found two ways to have OpenGL+GTK in the same window:

But there's a huge problem with both libraries.

With GtkGLExt, I can't use it because it doesn't find it when including.
And yes, I have checked a million times I have the packages installed.
I found out some other people also have the same issue. That's weird.

And I do exactly as GtkGLExt's tiny reference manual says:
Here's the code:

#include <gtk/gtkgl.h>


And he says:

error: gtk/gtkgl.h: No such file or directory

When I check the place manually, I find gtkgl.h where it should be.
I am supposed to be programming my game, not fixing these issues!

And there are very few examples or any help pages for GtkGLExt.
But enough I could do something with it if I'd play around for a while.

So, GtkGLExt does not work. How about GtkGLArea then? No idea.
Because there is not a single tutorial, reference manual, forum thread,nothing about it.

I don't even know which library to include! I googled sooo long I thought my head blows.

Just some download links where to download it from.
And it's homepage gives 404, and has been down for a while, according to google.

So I can't use GtkGLArea either because I don't know which header to include, where from,
or how to use the whole library.

Anybody has a better idea how to mix OGL and GUI? Or maybe tutorials for those libraries?
Solution for missing GtkGLExt header? Anything?

I originally was making a game. Then a map editor for the game.
But I can't do anything right now because there doesn't seem to be a way to create the map editor.
And that game was supposed to be a Soldat clone for Linux. Currently it's just lying on my hard drive.
Working map system, physics, textures, water, some basic stuff:


December 30th, 2008, 11:14 AM
Wright your own GUI lib which renders using OGL, like Blender for example.

December 30th, 2008, 01:07 PM
FLTK is a widget toolkit written using OpenGL.

December 30th, 2008, 01:20 PM
FLTK is for C++, I use C (and Python).

And writing my own GUI lib... Why to reinvent wheel the 10000th time?

December 30th, 2008, 05:59 PM
Maybe you can try Clutter (http://www.clutter-project.org/).

December 30th, 2008, 06:35 PM
Wright your own GUI lib which renders using OGL, like Blender for example.

Thats a tad excessive for a solution.

The error is because the compiler cant find the header file, gtk/gtkgl.h. Which I can see you are aware off. This header file in not in the default search location, /usr/local/include or /usr/include. It is in a sub directory of the base folder gtkglext or something so gtk/gtkgl wont find it.

On my computer to compile a c program using said library I would need to do something like -

gcc -I/usr/include/atk-1.0 -I/usr/include/gtkglext-1.0 -I/usr/lib64/gtkglext-1.0/include -I/usr/include/gtk-2.0 -I/usr/lib64/gtk-2.0/include -I/usr/include/pango-1.0 -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include -I/usr/include/cairo -I/usr/include/freetype2 -I/usr/include/libpng12 -I/usr/include/pixman-1 -Wl,--export-dynamic -latk-1.0 -lgdkglext-x11-1.0 -lGLU -lGL -lXmu -lXt -lSM -lICE -lgdk-x11-2.0 -lpangox-1.0 -lX11 -lgdk_pixbuf-2.0 -lpangocairo-1.0 -lcairo -lpango-1.0 -lgobject-2.0 -lgmodule-2.0 -ldl -lglib-2.0 -o hello bob.c

for example, now that is a pain in the ... so you can store it in your build file or you can just use pkg-config if you have it installed.

gcc `pkg-config --cflags --libs gdkglext-1.0` -I/usr/include/atk-1.0/ -latk-1.0 -o hello bob.c

That is how I do it when I'm playing with this stuff, whether that is the best solution or not, I don't know

January 1st, 2009, 12:23 PM
Clutter didn't want to compile, it just gave a ton of errors.

But I found GLUI, which is GUI done in pure OpenGL. Perfect for my needs,
except it doesn't compile either. Errors and warnings again :(

Unfortunately newest version of GLUI download link is broken, so I had to grab an older version.

But when I run "make" or "./configure" or anything I could compile it, it doesn't work.

All tools are installed, build-essentials, gcc, everything.

And linking with GtkGLExt didn't work. gcc didn't complain about gtk_gl_init() but it segfaulted.

January 4th, 2009, 04:13 AM
I've used gtkglext a good bit without any problems. I do recall having to install gtkglextmm from source, so I could use C++; I'm not sure if that's still the case or if it's in the repositories now.

One question - do you want an opengl drawing area inside of a normal GTK application window, with other GTK widgets around it; or do you want something like a fullscreen OpenGL window and the GUI drawn in OpenGL inside it?

If the latter, you could also try Crazy Eddie's GUI, which is used in the Ogre and Irrlicht engines: http://www.cegui.org.uk/wiki/index.php/Main_Page

January 4th, 2009, 05:02 AM
Try using pkg-config. Compiling gtk and friends usually requires a whole list of libraries too numerous to remember and too tedious to type by hand every time you compile.

Something like this should work:

gcc yourprogram.c -o yourprogram `pkg-config gtkglext-1.0 --cflags --libs`

If you're curious as to what the output of pkg-config actually looks like, you can type

pkg-config gtkglext-1.0 --libs

at the command prompt to get a list of the required libraries. These just get appended as arguments to the gcc command.

Remember that the ticks surrounding the pkg-config argument are not your normal single quotes. They are actually backticks which you type using the unshifted "tilde" (~) key. Single quotes will not work.

A makefile might also be something to consider...

I just noticed that bobrocks gave essentially the same answer a few days ago...reading too fast, too late at night I guess...

January 4th, 2009, 05:29 AM
I don't know if you've resolved the segfault issue with gtk_gl_init(), but you might try calling gtk_init() before calling gtk_gl_init().

My first attempt at a program that only calls gtk_gl_init() and closes gave me a segfault as well. Then I found a nice bit of sample code here:

http://www.cairographics.org/OpenGL/ (The "Beef it up a little" example actually uses GtkGlExt)

Here gtk_init() is called before gtk_gl_init(). Adding that to my tiny test program fixed the segfault. It may in your code too.

My sample code (compile using pkg-config as mentioned before):

#include <gtk/gtk.h>
#include <gtk/gtkgl.h>

int main(int argc, char ** argv)
gtk_init(&argc, &argv);
gtk_gl_init(&argc, &argv);

return 0;

Good Luck!

January 5th, 2009, 04:46 PM
I started writing my own, crappy, hardcoded GUI, which currently has:

Button, executes given functions on up/down events. Can have a texture overlay.
Text, doesn't do anything but displays text. Very useful.
Typeable textfield, only single line. Adjustable width.
Slider, can return it's position in percents. Adjustable width.
Selectable tab, has sub-widgets which are only active when tab is on top.

Button can also be used as a checkbox, with textures, functions and variables.

It isn't very good, and it doesn't have a separate header so it can't be used in any other program.

This sucks but it's easy as eating a pie. No need to mess with linking and compiling.
(Except coding, that's not easy, but I only code what I need, to make a map editor for my game.)

When I have time, I'll read your replies and try out the other GUI toolkits. And I noticed some C++ things there, I use just C.

Also, I found GLUI, which is GUI done entirely in OpenGL. But unfortunately it didn't want to compile and I had to download older
version because newest versions' download link was broken.

Why any existing ways of combining easy GUI and OpenGL don't work?
I have played, coded, ate, slept, and spent my whole short life on computers, but they just don't like me :(