Simplify creation of OpenGL contexts under X11 platform (#1005)

src/Fl_Gl_Choice.H

@@ -64,9 +64,6 @@ typedef NSOpenGLContext* FLOpenGLContextPtr;
 #else
 #  include <GL/glx.h>
 #  define GLContext GLXContext
-#  if ! defined(GLX_VERSION_1_3)
-#    typedef void *GLXFBConfig;
-#  endif
 #endif
 
 // Describes crap needed to create a GLContext.
@@ -83,7 +80,6 @@ public:
 #else
   XVisualInfo *vis;	// the visual to use
   Colormap colormap;	// a colormap for that visual
-  GLXFBConfig best_fb;
 #endif
   // Return one of these structures for a given gl mode.
   // The second argument is a glX attribute list, and is used if mode is

src/Fl_Gl_Choice.cxx

@@ -33,63 +33,6 @@ void fl_save_dc(HWND, HDC);
 extern void gl_texture_reset();
 #endif
 
-#if defined(USE_X11)
-static XVisualInfo *gl3_getvisual(const int *blist, GLXFBConfig *pbestFB)
-{
-  int glx_major, glx_minor;
-  
-  // FBConfigs were added in GLX version 1.3.
-  if ( !glXQueryVersion( fl_display, &glx_major, &glx_minor ) ||
-      ( ( glx_major == 1 ) && ( glx_minor < 3 ) ) || ( glx_major < 1 ) )
-  {
-    //printf("Invalid GLX version");
-    return NULL;
-  }
-  
-  //printf( "Getting matching framebuffer configs\n" );
-  int fbcount;
-  GLXFBConfig* fbc = glXChooseFBConfig(fl_display, DefaultScreen(fl_display), blist, &fbcount);
-  if (!fbc)
-  {
-    //printf( "Failed to retrieve a framebuffer config\n" );
-    return NULL;
-  }
-  //printf( "Found %d matching FB configs.\n", fbcount );
-  
-  // Pick the FB config/visual with the most samples per pixel
-  int best_fbc = -1, worst_fbc = -1, best_num_samp = -1, worst_num_samp = 999;
-  
-  int i;
-  for (i=0; i<fbcount; ++i)
-  {
-    XVisualInfo *vi = glXGetVisualFromFBConfig( fl_display, fbc[i] );
-    if ( vi )
-    {
-      int samp_buf, samples;
-      glXGetFBConfigAttrib( fl_display, fbc[i], GLX_SAMPLE_BUFFERS, &samp_buf );
-      glXGetFBConfigAttrib( fl_display, fbc[i], GLX_SAMPLES       , &samples  );
-      /*printf( "  Matching fbconfig %d, visual ID 0x%2lx: SAMPLE_BUFFERS = %d, SAMPLES = %d\n",
-       i, vi -> visualid, samp_buf, samples );*/
-      if ( best_fbc < 0 || (samp_buf && samples > best_num_samp) )
-        best_fbc = i, best_num_samp = samples;
-      if ( worst_fbc < 0 || !samp_buf || samples < worst_num_samp )
-        worst_fbc = i, worst_num_samp = samples;
-    }
-    XFree( vi );
-  }
-  
-  GLXFBConfig bestFbc = fbc[ best_fbc ];
-  
-  // Be sure to free the FBConfig list allocated by glXChooseFBConfig()
-  XFree( fbc );
-  
-  // Get a visual
-  XVisualInfo *vi = glXGetVisualFromFBConfig( fl_display, bestFbc );
-  *pbestFB = bestFbc;
-  return vi;
-}
-#endif
-
 static Fl_Gl_Choice *first;
 
 // this assumes one of the two arguments is zero:
@@ -153,19 +96,12 @@ Fl_Gl_Choice *Fl_Gl_Choice::find(int m, const int *alistp) {
   }
     
   fl_open_display();
-  XVisualInfo *visp = NULL;
+  XVisualInfo *visp = glXChooseVisual(fl_display, fl_screen, (int *)blist);
-  GLXFBConfig best_fb = NULL;
-  if (m & FL_OPENGL3) {
-    visp = gl3_getvisual((const int *)blist, &best_fb);
-  }
   if (!visp) {
-    visp = glXChooseVisual(fl_display, fl_screen, (int *)blist);
+#   if defined(GLX_VERSION_1_1) && defined(GLX_SGIS_multisample)
-    if (!visp) {
-#    if defined(GLX_VERSION_1_1) && defined(GLX_SGIS_multisample)
       if (m&FL_MULTISAMPLE) return find(m&~FL_MULTISAMPLE,0);
-#    endif
+#   endif
-      return 0;
+    return 0;
-    }
   }
 
 #elif defined(__APPLE_QUARTZ__)
@@ -256,7 +192,6 @@ Fl_Gl_Choice *Fl_Gl_Choice::find(int m, const int *alistp) {
 
 #if defined(USE_X11)
   g->vis = visp;
-  g->best_fb = best_fb;
 
   if (/*MaxCmapsOfScreen(ScreenOfDisplay(fl_display,fl_screen))==1 && */
       visp->visualid == fl_visual->visualid &&
@@ -317,38 +252,8 @@ static int ctxErrorHandler( Display *dpy, XErrorEvent *ev )
 GLContext fl_create_gl_context(Fl_Window *window, const Fl_Gl_Choice* g) {
   GLContext shared_ctx = 0;
   if (context_list && nContext) shared_ctx = context_list[0];
-  
+    
-  typedef GLContext (*glXCreateContextAttribsARBProc)(Display*, GLXFBConfig, GLContext, Bool, const int*);
+  GLContext ctx = glXCreateContext(fl_display, g->vis, shared_ctx, true);
-  
-  // It is not necessary to create or make current to a context before calling glXGetProcAddressARB
-  static glXCreateContextAttribsARBProc glXCreateContextAttribsARB =
-  (glXCreateContextAttribsARBProc)glXGetProcAddressARB((const GLubyte *)"glXCreateContextAttribsARB");
-  
-  GLContext ctx = 0;
-  
-  // Check for the GLX_ARB_create_context extension string and the function.
-  // If either is not present, use GLX 1.3 context creation method.
-  const char *glxExts = glXQueryExtensionsString(fl_display, fl_screen);
-  if (g->best_fb && strstr(glxExts, "GLX_ARB_create_context") && glXCreateContextAttribsARB ) {
-    int context_attribs[] =
-    {
-      GLX_CONTEXT_MAJOR_VERSION_ARB, 3,
-      GLX_CONTEXT_MINOR_VERSION_ARB, 2,
-      //GLX_CONTEXT_FLAGS_ARB        , GLX_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB,
-      //GLX_CONTEXT_PROFILE_MASK_ARB ,   GLX_CONTEXT_CORE_PROFILE_BIT_ARB ,
-      None
-    };
-    ctxErrorOccurred = false;
-    XErrorHandler oldHandler = XSetErrorHandler(&ctxErrorHandler);
-    ctx = glXCreateContextAttribsARB( fl_display, g->best_fb, shared_ctx, True, context_attribs );
-    // Sync to ensure any errors generated are processed.
-    XSync( fl_display, False );
-    if (ctxErrorOccurred) ctx = 0;
-    XSetErrorHandler(oldHandler);
-  }
-  if (!ctx) { // use OpenGL 1-style context creation
-    ctx = glXCreateContext(fl_display, g->vis, shared_ctx, true);
-  }
   if (ctx)
     add_context(ctx);
 //glXMakeCurrent(fl_display, fl_xid(window), ctx);printf("%s\n", glGetString(GL_VERSION));