1 /* xlock-gl.c --- xscreensaver compatibility layer for xlockmore GL modules.
2 * xscreensaver, Copyright (c) 1997-2008 Jamie Zawinski <jwz@jwz.org>
4 * Permission to use, copy, modify, distribute, and sell this software and its
5 * documentation for any purpose is hereby granted without fee, provided that
6 * the above copyright notice appear in all copies and that both that
7 * copyright notice and this permission notice appear in supporting
8 * documentation. No representations are made about the suitability of this
9 * software for any purpose. It is provided "as is" without express or
12 * This file, along with xlockmore.h, make it possible to compile an xlockmore
13 * GL module into a standalone program, and thus use it with xscreensaver.
14 * By Jamie Zawinski <jwz@jwz.org> on 31-May-97.
18 #include "xlockmoreI.h"
22 # define isupper(c) ((c) >= 'A' && (c) <= 'Z')
25 # define _tolower(c) ((c) - 'A' + 'a')
29 /* Gag -- we use this to turn X errors from glXCreateContext() into
30 something that will actually make sense to the user.
32 static XErrorHandler orig_ehandler = 0;
33 static Bool got_error = 0;
36 BadValue_ehandler (Display *dpy, XErrorEvent *error)
38 if (error->error_code == BadValue)
44 return orig_ehandler (dpy, error);
49 init_GL(ModeInfo * mi)
51 Display *dpy = mi->dpy;
52 Window window = mi->window;
53 Screen *screen = mi->xgwa.screen;
54 Visual *visual = mi->xgwa.visual;
55 GLXContext glx_context = 0;
56 XVisualInfo vi_in, *vi_out;
59 vi_in.screen = screen_number (screen);
60 vi_in.visualid = XVisualIDFromVisual (visual);
61 vi_out = XGetVisualInfo (dpy, VisualScreenMask|VisualIDMask,
63 if (! vi_out) abort ();
67 orig_ehandler = XSetErrorHandler (BadValue_ehandler);
68 glx_context = glXCreateContext (dpy, vi_out, 0, GL_TRUE);
70 XSetErrorHandler (orig_ehandler);
75 XFree((char *) vi_out);
79 fprintf(stderr, "%s: couldn't create GL context for visual 0x%x.\n",
80 progname, (unsigned int) XVisualIDFromVisual (visual));
84 glXMakeCurrent (dpy, window, glx_context);
87 GLboolean rgba_mode = 0;
88 glGetBooleanv(GL_RGBA_MODE, &rgba_mode);
91 glIndexi (WhitePixelOfScreen (screen));
92 glClearIndex (BlackPixelOfScreen (screen));
97 /* jwz: the doc for glDrawBuffer says "The initial value is GL_FRONT
98 for single-buffered contexts, and GL_BACK for double-buffered
99 contexts." However, I find that this is not always the case,
100 at least with Mesa 3.4.2 -- sometimes the default seems to be
101 GL_FRONT even when glGet(GL_DOUBLEBUFFER) is true. So, let's
104 Oh, hmm -- maybe this only happens when we are re-using the
105 xscreensaver window, and the previous GL hack happened to die with
106 the other buffer selected? I'm not sure. Anyway, this fixes it.
110 glGetBooleanv (GL_DOUBLEBUFFER, &d);
112 glDrawBuffer (GL_BACK);
114 glDrawBuffer (GL_FRONT);
117 /* Sometimes glDrawBuffer() throws "invalid op". Dunno why. Ignore. */
120 /* Process the -background argument. */
122 char *s = get_string_resource(mi->dpy, "background", "Background");
124 if (! XParseColor (dpy, mi->xgwa.colormap, s, &c))
125 fprintf (stderr, "%s: can't parse color %s; using black.\n",
127 glClearColor (c.red / 65535.0,
133 /* GLXContext is already a pointer type.
134 Why this function returns a pointer to a pointer, I have no idea...
137 GLXContext *ptr = (GLXContext *) malloc(sizeof(GLXContext));
145 /* clear away any lingering error codes */
147 clear_gl_error (void)
149 while (glGetError() != GL_NO_ERROR)
153 /* report a GL error. */
155 check_gl_error (const char *type)
160 switch ((i = glGetError())) {
161 case GL_NO_ERROR: return;
162 case GL_INVALID_ENUM: e = "invalid enum"; break;
163 case GL_INVALID_VALUE: e = "invalid value"; break;
164 case GL_INVALID_OPERATION: e = "invalid operation"; break;
165 case GL_STACK_OVERFLOW: e = "stack overflow"; break;
166 case GL_STACK_UNDERFLOW: e = "stack underflow"; break;
167 case GL_OUT_OF_MEMORY: e = "out of memory"; break;
168 #ifdef GL_TABLE_TOO_LARGE_EXT
169 case GL_TABLE_TOO_LARGE_EXT: e = "table too large"; break;
171 #ifdef GL_TEXTURE_TOO_LARGE_EXT
172 case GL_TEXTURE_TOO_LARGE_EXT: e = "texture too large"; break;
175 e = buf; sprintf (buf, "unknown error %d", (int) i); break;
177 fprintf (stderr, "%s: %s error: %s\n", progname, type, e);
182 /* Callback in xscreensaver_function_table, via xlockmore.c.
185 xlockmore_pick_gl_visual (Screen *screen)
187 /* pick the "best" visual by interrogating the GL library instead of
188 by asking Xlib. GL knows better.
191 Display *dpy = DisplayOfScreen (screen);
192 char *string = get_string_resource (dpy, "visualID", "VisualID");
196 for (s = string; *s; s++)
197 if (isupper (*s)) *s = _tolower (*s);
199 if (!string || !*string ||
200 !strcmp (string, "gl") ||
201 !strcmp (string, "best") ||
202 !strcmp (string, "color") ||
203 !strcmp (string, "default"))
204 v = get_gl_visual (screen); /* from ../utils/visual-gl.c */
213 /* Callback in xscreensaver_function_table, via xlockmore.c.
216 xlockmore_validate_gl_visual (Screen *screen, const char *name, Visual *visual)
218 return validate_gl_visual (stderr, screen, name, visual);