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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

22
src/video/windows/SDL_windowsopengl.c
View file

@ -112,10 +112,6 @@ WIN_GL_LoadLibrary(_THIS, const char *path)
GetProcAddress(handle, "wglDeleteContext");
_this->gl_data->wglMakeCurrent = (BOOL(WINAPI *) (HDC, HGLRC))
GetProcAddress(handle, "wglMakeCurrent");
_this->gl_data->wglSwapIntervalEXT = (void (WINAPI *) (int))
GetProcAddress(handle, "wglSwapIntervalEXT");
_this->gl_data->wglGetSwapIntervalEXT = (int (WINAPI *) (void))
GetProcAddress(handle, "wglGetSwapIntervalEXT");
if (!_this->gl_data->wglGetProcAddress ||
!_this->gl_data->wglCreateContext ||
@ -341,7 +337,7 @@ WIN_GL_InitExtensions(_THIS, HDC hdc)
}
/* Check for WGL_ARB_pixel_format */
_this->gl_data->WGL_ARB_pixel_format = 0;
_this->gl_data->HAS_WGL_ARB_pixel_format = SDL_FALSE;
if (HasExtension("WGL_ARB_pixel_format", extensions)) {
_this->gl_data->wglChoosePixelFormatARB = (BOOL(WINAPI *)
(HDC, const int *,
@ -354,16 +350,20 @@ WIN_GL_InitExtensions(_THIS, HDC hdc)
if ((_this->gl_data->wglChoosePixelFormatARB != NULL) &&
(_this->gl_data->wglGetPixelFormatAttribivARB != NULL)) {
_this->gl_data->WGL_ARB_pixel_format = 1;
_this->gl_data->HAS_WGL_ARB_pixel_format = SDL_TRUE;
}
}
/* Check for WGL_EXT_swap_control */
_this->gl_data->HAS_WGL_EXT_swap_control_tear = SDL_FALSE;
if (HasExtension("WGL_EXT_swap_control", extensions)) {
_this->gl_data->wglSwapIntervalEXT =
WIN_GL_GetProcAddress(_this, "wglSwapIntervalEXT");
_this->gl_data->wglGetSwapIntervalEXT =
WIN_GL_GetProcAddress(_this, "wglGetSwapIntervalEXT");
if (HasExtension("WGL_EXT_swap_control_tear", extensions)) {
_this->gl_data->HAS_WGL_EXT_swap_control_tear = SDL_TRUE;
}
} else {
_this->gl_data->wglSwapIntervalEXT = NULL;
_this->gl_data->wglGetSwapIntervalEXT = NULL;
@ -397,7 +397,7 @@ WIN_GL_ChoosePixelFormatARB(_THIS, int *iAttribs, float *fAttribs)
WIN_GL_InitExtensions(_this, hdc);
if (_this->gl_data->WGL_ARB_pixel_format) {
if (_this->gl_data->HAS_WGL_ARB_pixel_format) {
_this->gl_data->wglChoosePixelFormatARB(hdc, iAttribs, fAttribs,
1, &pixel_format,
&matching);
@ -611,7 +611,9 @@ WIN_GL_MakeCurrent(_THIS, SDL_Window * window, SDL_GLContext context)
int
WIN_GL_SetSwapInterval(_THIS, int interval)
{
if (_this->gl_data->wglSwapIntervalEXT) {
if ((interval < 0) && (!_this->gl_data->HAS_WGL_EXT_swap_control_tear)) {
SDL_SetError("Negative swap interval unsupported in this GL");
} else if (_this->gl_data->wglSwapIntervalEXT) {
_this->gl_data->wglSwapIntervalEXT(interval);
return 0;
} else {
@ -626,8 +628,8 @@ WIN_GL_GetSwapInterval(_THIS)
if (_this->gl_data->wglGetSwapIntervalEXT) {
return _this->gl_data->wglGetSwapIntervalEXT();
} else {
SDL_Unsupported();
return -1;
/*SDL_Unsupported();*/
return 0; /* just say we're unsync'd. */
}
}