SDL and OpenGL

SDL Development
21

When OpenGL is plattform independend, but the Initialisation is not, then
OpenGL Initialisation should be part of SDL, but no more.

Dierk Ohlerich
@Dierk_Ohlerich

22

a small snippet of code to show how I get OpenGL to point to a window
with GTK:

Note that you can actually do this with SDL under X11, using the
system-dependent window hooks in SDL_syswm.h:

/*

  • This function gives you custom hooks into the window manager information.
  • It fills the structure pointed to by ‘info’ with custom information and
  • returns 1 if the function is implemented. If it’s not implemented, it
  • returns 0.
  • If the version member of the ‘info’ structure isn’t valid, this function
  • returns -1.
    */
    SDL_DEFUN(int, SDL_GetWMInfo, (SDL_SysWMinfo *info))

For an example of working with the system-dependent window hooks, see
the ‘scrap’ example in the demos archive.

Display *dpy;
XVisualInfo *vi;
GLXContext glx_context;

dpy = GDK_WINDOW_XDISPLAY( window->window );

vi = glXChooseVisual( dpy, DefaultScreen(dpy), dblBuf );

if (vi == NULL)
{
  vi = glXChooseVisual( dpy, DefaultScreen(dpy), snglBuf);
  
  if(vi == NULL)
  {
  	FATAL("ERROR: glXChooseVisual failed.\n");
  	MyGLErrorExit();
  }
  else
  	DEBUGMSG(0,"Got a single-buffered display.\n");
}
else
  DEBUGMSG(0, "Got a double-buffered display.\n");

if (vi->c_class != TrueColor)

DEBUGMSG(0, “Non-TrueColor visual selected\n”);

DEBUGMSG(0, "Selected visual = %ld\n",vi->visualid );

glx_context = glXCreateContext( dpy, vi, None, GL_TRUE);

then in my render loop:

glXMakeCurrent( paneInfo.dpy,GDK_WINDOW_XWINDOW(paneInfo.myDrawArea->window),paneInfo.glx_context);

vector<Thing*> &reqList = GetList( WE_Render );

for( u_int i = 0; i < reqList.size(); i++ )
{
  DEBUGMSG(0, "Rendering the %s\n", reqList[i]->GetID() );
  reqList[i]->Render( paneNumber );
}

glXSwapBuffers(paneInfo.dpy,GDK_WINDOW_XWINDOW(paneInfo.myDrawArea->window));

jeff

See ya!
-Sam Lantinga (slouken at devolution.com)–
Author of Simple DirectMedia Layer -
http://www.devolution.com/~slouken/SDL/

23

“Dierk Ohlerich” <d_ohlerich at vcc.de> writes:

When OpenGL is plattform independend, but the Initialisation is not, then
OpenGL Initialisation should be part of SDL, but no more.

OpenGL initialization is perfectly platform independant…glut is made
for pretty much every platform I know of that runs OpenGL

and if glut isnt, all you need to do is pass a context or LPB to
OpenGL

j