ftp://ftp.uni-heidelberg.de/pub/X11/contrib/applications/xscreensaver-2.07.tar.gz

[xscreensaver] / hacks / glx / xlock-gl.c

diff --git a/hacks/glx/xlock-gl.c b/hacks/glx/xlock-gl.c
new file mode 100644 (file)
index 0000000..28ee7ca
--- /dev/null
+++ b/hacks/glx/xlock-gl.c
@@ -0,0 +1,173 @@
+/* xlock-gc.c --- xscreensaver compatibility layer for xlockmore GL modules.
+ * xscreensaver, Copyright (c) 1997 Jamie Zawinski <jwz@netscape.com>
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that
+ * copyright notice and this permission notice appear in supporting
+ * documentation.  No representations are made about the suitability of this
+ * software for any purpose.  It is provided "as is" without express or 
+ * implied warranty.
+ *
+ * This file, along with xlockmore.h, make it possible to compile an xlockmore
+ * GL module into a standalone program, and thus use it with xscreensaver.
+ * By Jamie Zawinski <jwz@netscape.com> on 31-May-97.
+ */
+
+#include <stdio.h>
+#include "screenhack.h"
+#include "xlockmoreI.h"
+
+#include <GL/gl.h>
+#include <GL/glx.h>
+
+/* Gag -- we use this to turn X errors from glXCreateContext() into
+   something that will actually make sense to the user.
+ */
+static XErrorHandler orig_ehandler = 0;
+static Bool got_error = 0;
+
+static int
+BadValue_ehandler (Display *dpy, XErrorEvent *error)
+{
+  if (error->error_code == BadValue)
+    {
+      got_error = True;
+      return 0;
+    }
+  else
+    return orig_ehandler (dpy, error);
+}
+
+
+GLXContext
+init_GL(ModeInfo * mi)
+{
+  Display *dpy = mi->dpy;
+  Window window = mi->window;
+  Screen *screen = mi->xgwa.screen;
+  Visual *visual = mi->xgwa.visual;
+  GLXContext glx_context = 0;
+  XVisualInfo vi_in, *vi_out;
+  int out_count;
+
+  vi_in.screen = screen_number (screen);
+  vi_in.visualid = XVisualIDFromVisual (visual);
+  vi_out = XGetVisualInfo (dpy, VisualScreenMask|VisualIDMask,
+                          &vi_in, &out_count);
+  if (! vi_out) abort ();
+
+  {
+    XSync (dpy, False);
+    orig_ehandler = XSetErrorHandler (BadValue_ehandler);
+    glx_context = glXCreateContext (dpy, vi_out, 0, GL_TRUE);
+    XSync (dpy, False);
+    XSetErrorHandler (orig_ehandler);
+    if (got_error)
+      glx_context = 0;
+  }
+
+  XFree((char *) vi_out);
+
+  if (!glx_context)
+    {
+      fprintf(stderr, "%s: couldn't create GL context for visual 0x%x.\n",
+             progname, (unsigned int) XVisualIDFromVisual (visual));
+      exit(1);
+    }
+
+  glXMakeCurrent (dpy, window, glx_context);
+
+  {
+    GLboolean rgba_mode = 0;
+    glGetBooleanv(GL_RGBA_MODE, &rgba_mode);
+    if (!rgba_mode)
+      {
+       glIndexi (WhitePixelOfScreen (screen));
+       glClearIndex (BlackPixelOfScreen (screen));
+      }
+  }
+
+  return (glx_context);
+}
+
+
+Visual *
+get_gl_visual (Screen *screen, char *name, char *class)
+{
+  char *string = get_string_resource (name, class);
+  XVisualInfo *vi = 0;
+  Bool done_once = False;
+
+ AGAIN:
+  if (!string || !*string ||
+      !strcmp (string, "best") ||
+      !strcmp (string, "color") ||
+      !strcmp (string, "default"))
+    {
+      Display *dpy = DisplayOfScreen (screen);
+      int screen_num = screen_number (screen);
+      int attrs[20];
+      int i = 0;
+      Bool dbuf_p = !get_boolean_resource ("noBuffer", "NoBuffer");
+
+      done_once = True;
+
+      attrs[i++] = GLX_RGBA;
+      attrs[i++] = GLX_RED_SIZE;   attrs[i++] = 1;
+      attrs[i++] = GLX_GREEN_SIZE; attrs[i++] = 1;
+      attrs[i++] = GLX_BLUE_SIZE;  attrs[i++] = 1;
+      attrs[i++] = GLX_DEPTH_SIZE; attrs[i++] = 1;
+      if (dbuf_p)
+       attrs[i++] = GLX_DOUBLEBUFFER;
+      attrs[i++] = 0;
+
+      vi = glXChooseVisual (dpy, screen_num, attrs);
+      if (vi) goto DONE;
+
+      /* Try without double-buffering. */
+      attrs[i - 1] = 0;
+      vi = glXChooseVisual (dpy, screen_num, attrs);
+      if (vi) goto DONE;
+
+      /* Try mono. */
+      i = 0;
+      if (dbuf_p)
+       attrs[i++] = GLX_DOUBLEBUFFER;
+      attrs[i++] = 0;
+      vi = glXChooseVisual (dpy, screen_num, attrs);
+      if (vi) goto DONE;
+
+      /* Try mono without double-buffering. */
+      attrs[0] = 0;
+      vi = glXChooseVisual (dpy, screen_num, attrs);
+    }
+
+ DONE:
+  {
+    Visual *v;
+    if (vi)
+      {
+       v = vi->visual;
+       XFree (vi);
+      }
+    else
+      {
+       v = get_visual (screen, string, False, True);
+       if (!v)
+         {
+           if (done_once)
+             v = DefaultVisualOfScreen (screen);
+           else
+             {
+               free (string);
+               string = 0;
+               goto AGAIN;
+             }
+         }
+      }
+
+    free (string);
+    return v;
+  }
+}