how to use glew with EGL when using desktop OpenGL?

[lugui2009]

Hello everybody:

I have an issue that I want use EGL to create context for desktop OpenGL .But I get segfault when executing my demo code. My graphic card is intel integrated card ,and my os is ubuntn.For more details about my pc ,take a look at image bellow.

I downloaded glew2.0.0 source code ,because I saw "OSMesa and EGL support". However, I encountered some warnings and an error (maybe not fatal error) when building .
Following codes were used(I followed the README):

when executing "make SYSTEM=linux-egl"
there were some warnings as follows,I were not so sure these warnings are fatal or not;

when executing "sudo make install"
It seemed to be OK

when executing "make clean"
I came out an error,I don't know why. I am an Admin user.

I were not sure that whether I builded the glew2.0 successfully or not successfully when using "SYSTEM=linux-egl",so someone can give me some help at this point.

And then I tested my code(I think maybe the build was successful) ,my test code as follows . I used X11+EGL+glew+desktop OpenGL.

#include <X11/Xlib.h>
#include <X11/Xatom.h>
#include <X11/Xutil.h>

#include <EGL/egl.h>
#include <EGL/eglext.h>
#include <GL/glew.h>
#include <GL/gl.h>

Display *x_display;
Window win;

EGLDisplay egl_display;
EGLContext egl_context;
EGLSurface egl_surface;

int main(int argc, char *argv[])
{

x_display = XOpenDisplay(NULL);
if(x_display ==NULL)
{
	std::cerr<<"cannot connect to X server"<<std::endl;
	return 1;
}

Window root = DefaultRootWindow(x_display);

XSetWindowAttributes  swa;
swa.event_mask = ExposureMask|PointerMotionMask|KeyPressMask;
win = XCreateWindow(x_display,root,0,0,800,480,0,CopyFromParent,InputOutput,CopyFromParent,CWEventMask,&swa);
XSetWindowAttributes xattr;

Atom atom;
int one =1;
xattr.override_redirect = False;
XChangeProperty(x_display,win,XInternAtom(x_display,"_NET_WM_STATE",True),XA_INTEGER,  32,  PropModeReplace,(unsigned char*) &one,  1);

XWMHints hints;
hints.input = True;
hints.flags = InputHint;
XSetWMHints(x_display, win, &hints);
XMapWindow ( x_display , win ); // make the window visible on the screen
XStoreName ( x_display , win , "GL test" );
Atom wm_state = XInternAtom ( x_display, "_NET_WM_STATE", False );
Atom fullscreen = XInternAtom ( x_display, "_NET_WM_STATE_FULLSCREEN", False );

XEvent xev;
memset ( &xev, 0, sizeof(xev) );

xev.type = ClientMessage;
xev.xclient.window = win;
xev.xclient.message_type = wm_state;
xev.xclient.format = 32;
xev.xclient.data.l[0] = 1;
xev.xclient.data.l[1] = fullscreen;
XSendEvent ( // send an event mask to the X-server
x_display,
DefaultRootWindow ( x_display ),
False,
SubstructureNotifyMask,
&xev );

//SET UP EGL

egl_display  =  eglGetDisplay( (EGLNativeDisplayType) x_display );  

if ( egl_display == EGL_NO_DISPLAY ) {
std::cerr << "Got no EGL display." << std::endl;
return 1;
}

EGLint major, minor;
if ( !eglInitialize( egl_display, &major, &minor ) ) {
std::cerr << "Unable to initialize EGL" << std::endl;
return 1;
}
std::cout<<"The major vesion is "<<major<<std::endl;
std::cout<<"The minor vesion is "<<minor<<std::endl;

EGLint attr[] = {
EGL_RENDERABLE_TYPE, EGL_OPENGL_BIT,
EGL_NONE
};

EGLConfig ecfg;
EGLint num_config;
if ( !eglChooseConfig( egl_display, attr, &ecfg, 1, &num_config ) ) {
std::cerr << "Failed to choose config (eglError: " << eglGetError() << ")" << std ::endl;
return 1;
}

if ( num_config != 1 ) {
std::cerr << "Didn't get exactly one config, but " << num_config << std::endl;
return 1;
}
if(!eglBindAPI (EGL_OPENGL_API))
{
std::cerr<<"Bind EGL_OPENGL_API failed ,crying!"<<std::endl;
return 1;
}
egl_surface = eglCreateWindowSurface ( egl_display, ecfg, win, NULL );
if ( egl_surface == EGL_NO_SURFACE ) {
std::cerr << "Unable to create EGL surface (eglError: " << eglGetError() << ")" << std::endl;
return 1;
}

EGLint ctxattr[] = {
EGL_CONTEXT_MAJOR_VERSION, 4,
EGL_CONTEXT_MINOR_VERSION, 5,
EGL_CONTEXT_OPENGL_PROFILE_MASK_KHR,
EGL_CONTEXT_OPENGL_CORE_PROFILE_BIT_KHR,
EGL_NONE
};

egl_context = eglCreateContext ( egl_display, ecfg, EGL_NO_CONTEXT, ctxattr );
if ( egl_context == EGL_NO_CONTEXT ) {
std::cerr << "Unable to create EGL context (eglError: " << eglGetError() << ")" << std::endl;
return 1;
}

eglMakeCurrent( egl_display, egl_surface, egl_surface, egl_context );

std::cout<<"I am above glew!!"<<std::endl;
glewExperimental = GL_TRUE;
std::cout<<glGetError()<<std::endl;
std::cout<<"I am between glewExperimental and glewInit()"<<std::endl;
glewInit();
std::cout<<glGetError()<<std::endl;
std::cout<<"I am below glew!!"<<std::endl;
std::cout<<"The OpenGL version is :"<<glGetString(GL_VERSION)<<std::endl;

bool quit=false;
while(!quit)
{
while(XPending(x_display))
{
XEvent xev;
XNextEvent(x_display,&xev);
if(xev.type == KeyPress)
{
quit = true;
}
}

   static XWindowAttributes gwa;
   XGetWindowAttributes(x_display,win,&gwa);
   glClearColor(0.8f, 0.5f, 0.4f, 1.0f);
   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
   glViewport(0,0,gwa.width,gwa.height);
   
   eglSwapBuffers(egl_display,egl_surface);

}

eglDestroyContext ( egl_display, egl_context );
eglDestroySurface ( egl_display, egl_surface );
eglTerminate ( egl_display );
XDestroyWindow ( x_display, win );
XCloseDisplay ( x_display );

return 0;

}

build g++ X11eglGLewSimple.cpp -o X11eglGLewSimple.out -lGLEW -lGL -lX11 -lEGL

But I got the segment bellows when entering glewInit(),I don't know how to deal with it .

I found a strange thingthat my code could be executed successfully when I used Nvidia even though I used glew 1.13. But I encountered segment fault when using integrated card.Can someone help me?give me some tips or documents or something else ,or should I give more information.thank you very much.

[nigels-com]

There were some EGL fixes for GLEW 2.1.0. Could you give that a try?

glew.sourceforge.net

[lugui2009]

@nigels-com I have also tried 2.1.0. However I got the same error.

[nigels-com]

Did you have any luck running glewinfo on that GPU/driver?

This is what I get on an Intel GPU:

$ LD_LIBRARY_PATH=`pwd`/lib DISPLAY=:0 bin/glewinfo
---------------------------
    GLEW Extension Info
---------------------------

GLEW version 2.1.0
Running on a Mesa DRI Intel(R) Iris Pro Graphics 580 (Skylake GT4e)  from Intel Open Source Technology Center
OpenGL version 3.0 Mesa 17.0.7 is supported

GL_VERSION_1_1:                                                OK
---------------

GL_VERSION_1_2:                                                OK
---------------
  glCopyTexSubImage3D:                                         OK
  glDrawRangeElements:                                         OK
  glTexImage3D:                                                OK
  glTexSubImage3D:                                             OK
...

[nigels-com]

For the attached test code, I get a context creation failure.
I tried xfce and Gnome on Ubuntu 17.10

The major vesion is 1
The minor vesion is 4
Unable to create EGL context (eglError: 12297)

[nigels-com]

The test program worked for me with a small change to request OpenGL 2.1:

EGL_CONTEXT_MAJOR_VERSION, 2,
EGL_CONTEXT_MINOR_VERSION, 1,