1 /* xlock-gl.c --- xscreensaver compatibility layer for xlockmore GL modules.
2 * xscreensaver, Copyright (c) 1997-2014 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;
63 vi_in.screen = screen_number (screen);
64 vi_in.visualid = XVisualIDFromVisual (visual);
65 vi_out = XGetVisualInfo (dpy, VisualScreenMask|VisualIDMask,
67 if (! vi_out) abort ();
71 orig_ehandler = XSetErrorHandler (BadValue_ehandler);
72 glx_context = glXCreateContext (dpy, vi_out, 0, GL_TRUE);
74 XSetErrorHandler (orig_ehandler);
79 XFree((char *) vi_out);
83 fprintf(stderr, "%s: couldn't create GL context for visual 0x%x.\n",
84 progname, (unsigned int) XVisualIDFromVisual (visual));
88 glXMakeCurrent (dpy, window, glx_context);
91 GLboolean rgba_mode = 0;
92 glGetBooleanv(GL_RGBA_MODE, &rgba_mode);
95 glIndexi (WhitePixelOfScreen (screen));
96 glClearIndex (BlackPixelOfScreen (screen));
101 /* jwz: the doc for glDrawBuffer says "The initial value is GL_FRONT
102 for single-buffered contexts, and GL_BACK for double-buffered
103 contexts." However, I find that this is not always the case,
104 at least with Mesa 3.4.2 -- sometimes the default seems to be
105 GL_FRONT even when glGet(GL_DOUBLEBUFFER) is true. So, let's
108 Oh, hmm -- maybe this only happens when we are re-using the
109 xscreensaver window, and the previous GL hack happened to die with
110 the other buffer selected? I'm not sure. Anyway, this fixes it.
114 glGetBooleanv (GL_DOUBLEBUFFER, &d);
116 glDrawBuffer (GL_BACK);
118 glDrawBuffer (GL_FRONT);
121 /* Sometimes glDrawBuffer() throws "invalid op". Dunno why. Ignore. */
124 /* Process the -background argument. */
126 char *s = get_string_resource(mi->dpy, "background", "Background");
128 if (! XParseColor (dpy, mi->xgwa.colormap, s, &c))
129 fprintf (stderr, "%s: can't parse color %s; using black.\n",
131 glClearColor (c.red / 65535.0,
137 /* GLXContext is already a pointer type.
138 Why this function returns a pointer to a pointer, I have no idea...
141 GLXContext *ptr = (GLXContext *) malloc(sizeof(GLXContext));
149 /* clear away any lingering error codes */
151 clear_gl_error (void)
153 while (glGetError() != GL_NO_ERROR)
157 /* report a GL error. */
159 check_gl_error (const char *type)
164 switch ((i = glGetError())) {
165 case GL_NO_ERROR: return;
166 case GL_INVALID_ENUM: e = "invalid enum"; break;
167 case GL_INVALID_VALUE: e = "invalid value"; break;
168 case GL_INVALID_OPERATION: e = "invalid operation"; break;
169 case GL_STACK_OVERFLOW: e = "stack overflow"; break;
170 case GL_STACK_UNDERFLOW: e = "stack underflow"; break;
171 case GL_OUT_OF_MEMORY: e = "out of memory"; break;
172 #ifdef GL_TABLE_TOO_LARGE_EXT
173 case GL_TABLE_TOO_LARGE_EXT: e = "table too large"; break;
175 #ifdef GL_TEXTURE_TOO_LARGE_EXT
176 case GL_TEXTURE_TOO_LARGE_EXT: e = "texture too large"; break;
179 e = buf; sprintf (buf, "unknown error %d", (int) i); break;
181 fprintf (stderr, "%s: %s error: %s\n", progname, type, e);
186 /* Callback in xscreensaver_function_table, via xlockmore.c.
189 xlockmore_pick_gl_visual (Screen *screen)
191 /* pick the "best" visual by interrogating the GL library instead of
192 by asking Xlib. GL knows better.
195 Display *dpy = DisplayOfScreen (screen);
196 char *string = get_string_resource (dpy, "visualID", "VisualID");
200 for (s = string; *s; s++)
201 if (isupper (*s)) *s = _tolower (*s);
203 if (!string || !*string ||
204 !strcmp (string, "gl") ||
205 !strcmp (string, "best") ||
206 !strcmp (string, "color") ||
207 !strcmp (string, "default"))
208 v = get_gl_visual (screen); /* from ../utils/visual-gl.c */
217 /* Callback in xscreensaver_function_table, via xlockmore.c.
220 xlockmore_validate_gl_visual (Screen *screen, const char *name, Visual *visual)
222 return validate_gl_visual (stderr, screen, name, visual);