Changed OpenGL support for the Mac OS X platform: use cocoa instead of deprecated AGL.

All changes are mac-specific, except a very minor change in file src/gl_draw.cxx
where string drawing wrongly claimed to support @symbol, not possible
because symbols are drawn using non-GL primitives.

Unchanged application code can use the new FLTK code.
In addition, the new code allows mac applications to draw OpenGL scenes
at high resolution on so-called 'retina' displays, but this requires some
support from app code. They must call, before opening GL windows,
Fl::use_high_resolution(1);
and change their glViewport() calls as follows
glViewport(0, 0, pxel_w(), pixel_h());
This uses 2 new member functions of the Fl_Gl_Window class,
pixel_w() and pixel_h() returning the window dimensions in pixel
units, that is, twice the w() and h() when the window is mapped
on a retina display.


git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@10498 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

test/fullscreen.cxx

@@ -84,7 +84,7 @@ void shape_window::draw() {
     valid(1);
 //  printf("init\n");
     glLoadIdentity();
-    glViewport(0,0,w(),h());
+    glViewport(0,0,pixel_w(),pixel_h());
   }
   glClear(GL_COLOR_BUFFER_BIT);
   glColor3f(.5,.6,.7);
@@ -267,6 +267,7 @@ int arg(int, char **argv, int &i) {
 
 int main(int argc, char **argv) {
 
+  Fl::use_high_res_GL(1);
   int i=0;
   if (Fl::args(argc,argv,i,arg) < argc)
     Fl::fatal("Options are:\n -2 = 2 windows\n -f = startup fullscreen\n%s",Fl::help);