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static bool g_glx_context_error_occured = false;
static int glx_context_error_handler(Display *display, XErrorEvent *event)
{
printf("glx_context_error_handler received error\n");
g_glx_context_error_occured = true;
return 0;
}
// Helper to check for extension string presence. Copied from:
// http://www.opengl.org/resources/features/OGLextensions/
static bool gl_extension_supported(const char *extList, const char *extension)
{
const char *start;
const char *where, *terminator;
// Extension names should not have spaces.
where = strchr(extension, ' ');
if (where || *extension == '\0')
return false;
for (start=extList;;)
{
where = strstr(start, extension);
if (!where)
break;
terminator = where + strlen(extension);
if (where == start || *(where - 1) == ' ')
if (*terminator == ' ' || *terminator == '\0')
return true;
start = terminator;
}
return false;
}
static GLXContext create_current_glx_context(Display *display, Window window, GLXFBConfig fbc)
{
// get glXCreateContextAttribsARB
const char *glx_extensions = glXQueryExtensionsString(display, DefaultScreen( display));
glXCreateContextAttribsARBProc glXCreateContextAttribsARB = 0;
glXCreateContextAttribsARB = (glXCreateContextAttribsARBProc) glXGetProcAddressARB((const GLubyte*)"glXCreateContextAttribsARB");
if (!gl_extension_supported(glx_extensions, "GLX_ARB_create_context") ||
!glXCreateContextAttribsARB)
{
printf("glXCreateContextAttribsARB() not found\n");
return 0;
}
// Install an X error handler so the application won't exit if GL 3.0
// context allocation fails.
//
// Note this error handler is global. All display connections in all threads
// of a process use the same error handler, so be sure to guard against other
// threads issuing X commands while this code is running.
g_glx_context_error_occured = false;
int (*oldHandler)(Display*, XErrorEvent*) = XSetErrorHandler(&glx_context_error_handler);
// create glx context
GLXContext glx_context = 0;
int context_attribs[] = {
GLX_CONTEXT_MAJOR_VERSION_ARB, 4,
GLX_CONTEXT_MINOR_VERSION_ARB, 3,
GLX_CONTEXT_FLAGS_ARB, GLX_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB | GLX_CONTEXT_DEBUG_BIT_ARB,
GLX_CONTEXT_PROFILE_MASK_ARB, GLX_CONTEXT_CORE_PROFILE_BIT_ARB,
None
};
glx_context = glXCreateContextAttribsARB(display, fbc, 0, True, context_attribs);
// check for errors
XSync(display, False);
if (g_glx_context_error_occured || !glx_context)
{
printf("failed to create glx context\n");
return 0;
}
XSetErrorHandler(oldHandler);
glXMakeCurrent(display, window, glx_context);
return glx_context;
}
// Note: special case when debugging
// stepping over glXChooseFBConfig or glXGetFBConfigs cause
// _dl_catch_exception in libc
// stepping more leads to
// ?? () from /usr/lib/libnvidia-glcore.so.510.68.02
//
// Originally I used glXChooseFBConfig, then tried to fix it with glXGetFBConfigs
// and now I leave it at that for the time being
//
// You can still debug by setting breakpoint later and continuing (c) until
// that breakpoint is hit
static bool get_framebuffer_config(Display *display, GLXFBConfig *config)
{
int screen = XDefaultScreen(display);
int fbcs_count;
GLXFBConfig *fbcs = glXGetFBConfigs(display, screen, &fbcs_count);
if (!fbcs)
{
printf("no framebuffer configs received\n");
return 0;
}
int best_fbc = -1, worst_fbc = -1, best_num_samp = -1, worst_num_samp = 999;
for (int i = 0; i < fbcs_count; i++)
{
int fbc_attribs[11];
glXGetFBConfigAttrib(display, fbcs[i], GLX_X_RENDERABLE, &fbc_attribs[0]);
glXGetFBConfigAttrib(display, fbcs[i], GLX_DRAWABLE_TYPE, &fbc_attribs[1]);
glXGetFBConfigAttrib(display, fbcs[i], GLX_RENDER_TYPE, &fbc_attribs[2]);
glXGetFBConfigAttrib(display, fbcs[i], GLX_X_VISUAL_TYPE, &fbc_attribs[3]);
glXGetFBConfigAttrib(display, fbcs[i], GLX_RED_SIZE, &fbc_attribs[4]);
glXGetFBConfigAttrib(display, fbcs[i], GLX_GREEN_SIZE, &fbc_attribs[5]);
glXGetFBConfigAttrib(display, fbcs[i], GLX_BLUE_SIZE, &fbc_attribs[6]);
glXGetFBConfigAttrib(display, fbcs[i], GLX_ALPHA_SIZE, &fbc_attribs[7]);
glXGetFBConfigAttrib(display, fbcs[i], GLX_DEPTH_SIZE, &fbc_attribs[8]);
glXGetFBConfigAttrib(display, fbcs[i], GLX_STENCIL_SIZE, &fbc_attribs[9]);
glXGetFBConfigAttrib(display, fbcs[i], GLX_DOUBLEBUFFER, &fbc_attribs[10]);
if (fbc_attribs[0] == True &&
fbc_attribs[1] & GLX_WINDOW_BIT &&
fbc_attribs[2] & GLX_RGBA_BIT &&
fbc_attribs[3] == GLX_TRUE_COLOR &&
fbc_attribs[4] == 8 &&
fbc_attribs[5] == 8 &&
fbc_attribs[6] == 8 &&
fbc_attribs[7] == 8 &&
fbc_attribs[8] == 24 &&
fbc_attribs[9] == 8 &&
fbc_attribs[10] == True)
{
XVisualInfo *visual_info = glXGetVisualFromFBConfig(display, fbcs[i]);
if (visual_info)
{
int samp_buf, samples;
glXGetFBConfigAttrib(display, fbcs[i], GLX_SAMPLE_BUFFERS, &samp_buf);
glXGetFBConfigAttrib(display, fbcs[i], GLX_SAMPLES , &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(visual_info);
}
}
if (best_fbc == -1)
{
return false;
}
*config = fbcs[best_fbc];
XFree(fbcs);
return true;
}
struct Platform_Window* platform_create_window(const char *name, int width, int height)
{
Display *display = XOpenDisplay(0);
if (!display)
{
printf("XOpenDisplay(0) failed\n");
return 0;
}
Window root_window = XDefaultRootWindow(display);
if (!root_window)
{
printf("XDefaultRootWindow(display) failed\n");
XCloseDisplay(display);
return 0;
}
// glx version 1.3 required (for framebuffer configs and modern context creation)
int glx_major, glx_minor;
if (!glXQueryVersion(display, &glx_major, &glx_minor) ||
(glx_major == 1 && glx_minor < 3) ||
(glx_major < 1))
{
printf("invalid glx version\n");
return 0;
}
GLXFBConfig fbc;
if (!get_framebuffer_config(display, &fbc))
{
printf("no framebuffer config found\n");
return 0;
}
// set window attributes
XVisualInfo *visual_info = glXGetVisualFromFBConfig(display, fbc);
Colormap colormap = XCreateColormap(display, root_window, visual_info->visual, AllocNone);
long event_mask = StructureNotifyMask | KeyPressMask | KeyReleaseMask | ButtonPressMask | ButtonReleaseMask;
int attribute_mask = CWEventMask | CWColormap;
XSetWindowAttributes attributes = {};
attributes.colormap = colormap;
attributes.event_mask = event_mask;
// create window
Window window = XCreateWindow(display, root_window, 0, 0, width, height, 0, visual_info->depth, InputOutput, visual_info->visual, attribute_mask, &attributes);
XFree(visual_info);
XStoreName(display, window, name);
XMapWindow(display, window);
GLXContext glx_context = create_current_glx_context(display, window, fbc);
if (!glx_context)
{
return 0;
}
// create platform window
struct Platform_Window *platform_window = (struct Platform_Window*)malloc(sizeof(struct Platform_Window));
if (!platform_window)
{
printf("malloc failed\n");
XCloseDisplay(display);
return 0;
}
platform_window->display = display;
platform_window->window = window;
return platform_window;
}
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