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Add support for (GLX|WGL)_EXT_swap_control_tear.

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This required a small public API change: SDL_GL_SetSwapInterval() now accepts
 negative values, and SDL_GL_GetSwapInterval() doesn't report errors anymore
 (if it can't work, it'll return zero as a reasonable default).

If you need to test for errors, such as a lack of swap_control_tear support,
 check the results of SDL_GL_SetSwapInterval() when you set your desired
 value.
This commit is contained in:
Ryan C. Gordon 2012-08-01 20:29:36 -04:00
parent 706ea79345
commit 2cd5fc4e97
10 changed files with 67 additions and 52 deletions
Download patch file Download diff file Expand all files Collapse all files

39
src/video/x11/SDL_x11opengl.c
View file

@ -105,6 +105,10 @@ typedef GLXContext(*PFNGLXCREATECONTEXTATTRIBSARBPROC) (Display * dpy,
#define GLX_MAX_SWAP_INTERVAL_EXT 0x20F2
#endif
#ifndef GLX_EXT_swap_control_tear
#define GLX_LATE_SWAPS_TEAR_EXT 0x20F3
#endif
#define OPENGL_REQUIRES_DLOPEN
#if defined(OPENGL_REQUIRES_DLOPEN) && defined(SDL_LOADSO_DLOPEN)
#include <dlfcn.h>
@ -318,11 +322,15 @@ X11_GL_InitExtensions(_THIS)
extensions = NULL;
}
/* Check for GLX_EXT_swap_control */
/* Check for GLX_EXT_swap_control(_tear) */
_this->gl_data->HAS_GLX_EXT_swap_control_tear = SDL_FALSE;
if (HasExtension("GLX_EXT_swap_control", extensions)) {
_this->gl_data->glXSwapIntervalEXT =
(int (*)(Display*,GLXDrawable,int))
X11_GL_GetProcAddress(_this, "glXSwapIntervalEXT");
if (HasExtension("GLX_EXT_swap_control_tear", extensions)) {
_this->gl_data->HAS_GLX_EXT_swap_control_tear = SDL_TRUE;
}
}
/* Check for GLX_MESA_swap_control */
@ -615,9 +623,11 @@ static int swapinterval = -1;
int
X11_GL_SetSwapInterval(_THIS, int interval)
{
int status;
int status = -1;
if (_this->gl_data->glXSwapIntervalEXT) {
if ((interval < 0) && (!_this->gl_data->HAS_GLX_EXT_swap_control_tear)) {
SDL_SetError("Negative swap interval unsupported in this GL");
} else if (_this->gl_data->glXSwapIntervalEXT) {
Display *display = ((SDL_VideoData *) _this->driverdata)->display;
const SDL_WindowData *windowdata = (SDL_WindowData *)
_this->current_glwin->driverdata;
@ -625,7 +635,6 @@ X11_GL_SetSwapInterval(_THIS, int interval)
status = _this->gl_data->glXSwapIntervalEXT(display,drawable,interval);
if (status != 0) {
SDL_SetError("glxSwapIntervalEXT failed");
status = -1;
} else {
swapinterval = interval;
}
@ -633,7 +642,6 @@ X11_GL_SetSwapInterval(_THIS, int interval)
status = _this->gl_data->glXSwapIntervalMESA(interval);
if (status != 0) {
SDL_SetError("glxSwapIntervalMESA failed");
status = -1;
} else {
swapinterval = interval;
}
@ -641,13 +649,11 @@ X11_GL_SetSwapInterval(_THIS, int interval)
status = _this->gl_data->glXSwapIntervalSGI(interval);
if (status != 0) {
SDL_SetError("glxSwapIntervalSGI failed");
status = -1;
} else {
swapinterval = interval;
}
} else {
SDL_Unsupported();
status = -1;
}
return status;
}
@ -660,10 +666,23 @@ X11_GL_GetSwapInterval(_THIS)
const SDL_WindowData *windowdata = (SDL_WindowData *)
_this->current_glwin->driverdata;
Window drawable = windowdata->xwindow;
unsigned int value = 0;
unsigned int allow_late_swap_tearing = 0;
unsigned int interval = 0;
if (_this->gl_data->HAS_GLX_EXT_swap_control_tear) {
_this->gl_data->glXQueryDrawable(display, drawable,
GLX_LATE_SWAPS_TEAR_EXT,
&allow_late_swap_tearing);
}
_this->gl_data->glXQueryDrawable(display, drawable,
GLX_SWAP_INTERVAL_EXT, &value);
return (int) value;
GLX_SWAP_INTERVAL_EXT, &interval);
if ((allow_late_swap_tearing) && (interval > 0)) {
return -((int) interval);
}
return (int) interval;
} else if (_this->gl_data->glXGetSwapIntervalMESA) {
return _this->gl_data->glXGetSwapIntervalMESA();
} else {