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Implemented bug #2, 117:

Date: Mon, 21 Mar 2005 12:06:14 +0100
From: Per Inge Mathisen
Subject: Re: [SDL] Outstanding patches?

The patch adds support for setting SDL_GL_SWAP_CONTROL to Windows and
X11. In Windows you can also query this enum to check that it is
working, or see what the default is - such functionality does not
exist in GLX. For more information on the standards implemented:
http://oss.sgi.com/projects/ogl-sample/registry/SGI/swap_control.txt
http://oss.sgi.com/projects/ogl-sample/registry/EXT/wgl_swap_control.txt
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slouken committed Apr 27, 2006
1 parent 000fdde commit 2da0e7b7f625000f1a0086f6bf4c27d75754b690
@@ -4,6 +4,8 @@ This is a list of API changes in SDL's version history.
Version 1.0:

1.2.10:
Added SDL_GL_SWAP_CONTROL to wait for vsync in OpenGL applications.

Added current_w and current_h to the SDL_VideoInfo structure,
which is set to the desktop resolution during video intialization,
and then set to the current resolution when a video mode is set.
@@ -213,7 +213,8 @@ typedef enum {
SDL_GL_ACCUM_ALPHA_SIZE,
SDL_GL_STEREO,
SDL_GL_MULTISAMPLEBUFFERS,
SDL_GL_MULTISAMPLESAMPLES
SDL_GL_MULTISAMPLESAMPLES,
SDL_GL_SWAP_CONTROL
} SDL_GLattr;

/* flags for SDL_SetPalette() */
@@ -292,6 +292,7 @@ struct SDL_VideoDevice {
int stereo;
int multisamplebuffers;
int multisamplesamples;
int swap_control;
int driver_loaded;
char driver_path[256];
void* dll_handle;
@@ -233,6 +233,7 @@ int SDL_VideoInit (const char *driver_name, Uint32 flags)
video->gl_config.stereo = 0;
video->gl_config.multisamplebuffers = 0;
video->gl_config.multisamplesamples = 0;
video->gl_config.swap_control = -1; /* not known, don't set */

/* Initialize the video subsystem */
SDL_memset(&vformat, 0, sizeof(vformat));
@@ -1474,6 +1475,9 @@ int SDL_GL_SetAttribute( SDL_GLattr attr, int value )
case SDL_GL_MULTISAMPLESAMPLES:
video->gl_config.multisamplesamples = value;
break;
case SDL_GL_SWAP_CONTROL:
video->gl_config.swap_control = value;
break;
default:
SDL_SetError("Unknown OpenGL attribute");
retval = -1;
@@ -132,6 +132,17 @@ int QZ_SetupOpenGL (_THIS, int bpp, Uint32 flags) {
return 0;
}

/* Synchronize QZ_GL_SwapBuffers() to vertical retrace.
* (Apple's documentation is not completely clear about what this setting
* exactly does, IMHO - for a detailed explanation see
* http://lists.apple.com/archives/mac-opengl/2006/Jan/msg00080.html )
*/
if ( this->gl_config.swap_control >= 0 ) {
long value;
value = this->gl_config.swap_control;
[ gl_context setValues: &value forParameter: NSOpenGLCPSwapInterval ];
}

/*
* Wisdom from Apple engineer in reference to UT2003's OpenGL performance:
* "You are blowing a couple of the internal OpenGL function caches. This
@@ -177,6 +177,7 @@ int WIN_GL_SetupWindow(_THIS)
int iAttribs[64];
int *iAttr;
float fAttribs[1] = { 0 };
const char *wglext;

/* load the gl driver from a default path */
if ( ! this->gl_config.driver_loaded ) {
@@ -323,7 +324,25 @@ int WIN_GL_SetupWindow(_THIS)
SDL_SetError("Unable to create GL context");
return(-1);
}
if ( WIN_GL_MakeCurrent(this) < 0 ) {
return(-1);
}
gl_active = 1;

/* Vsync control under Windows. Checking glGetString here is
* somewhat a documented and reliable hack - it was originally
* as a feature added by mistake, but since so many people rely
* on it, it will not be removed. strstr should be safe here.*/
wglext = (const char *)this->glGetString(GL_EXTENSIONS);
if ( !SDL_strstr(wglext, "WGL_EXT_swap_control") ) {
this->gl_data->wglSwapIntervalEXT = NULL;
this->gl_data->wglGetSwapIntervalEXT = NULL;
}
if ( this->gl_config.swap_control >= 0 ) {
if ( this->gl_data->wglSwapIntervalEXT ) {
this->gl_data->wglSwapIntervalEXT(this->gl_config.swap_control);
}
}
#else
SDL_SetError("WIN driver not configured with OpenGL");
#endif
@@ -423,6 +442,12 @@ int WIN_GL_GetAttribute(_THIS, SDL_GLattr attrib, int* value)
case SDL_GL_MULTISAMPLESAMPLES:
wgl_attrib = WGL_SAMPLES_ARB;
break;
case SDL_GL_SWAP_CONTROL:
if ( this->gl_data->wglGetSwapIntervalEXT ) {
return this->gl_data->wglGetSwapIntervalEXT();
} else {
return -1;
}
default:
return(-1);
}
@@ -509,6 +534,8 @@ void WIN_GL_UnloadLibrary(_THIS)
this->gl_data->wglMakeCurrent = NULL;
this->gl_data->wglChoosePixelFormatARB = NULL;
this->gl_data->wglGetPixelFormatAttribivARB = NULL;
this->gl_data->wglSwapIntervalEXT = NULL;
this->gl_data->wglGetSwapIntervalEXT = NULL;

this->gl_config.dll_handle = NULL;
this->gl_config.driver_loaded = 0;
@@ -547,6 +574,10 @@ int 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 == NULL) ||
(this->gl_data->wglCreateContext == NULL) ||
@@ -53,6 +53,8 @@ struct SDL_PrivateGLData {
UINT nAttributes,
const int *piAttributes,
int *piValues);
void (WINAPI *wglSwapIntervalEXT)(int interval);
int (WINAPI *wglGetSwapIntervalEXT)(void);
#endif /* SDL_VIDEO_OPENGL */
};

@@ -205,18 +205,39 @@ int X11_GL_CreateContext(_THIS)
{
int retval;
#if SDL_VIDEO_OPENGL_GLX
const char *glXext;

/* We do this to create a clean separation between X and GLX errors. */
XSync( SDL_Display, False );
glx_context = this->gl_data->glXCreateContext(GFX_Display,
glx_visualinfo, NULL, True);
XSync( GFX_Display, False );

if (glx_context == NULL) {
if ( glx_context == NULL ) {
SDL_SetError("Could not create GL context");
return -1;
return(-1);
}
if ( X11_GL_MakeCurrent(this) < 0 ) {
return(-1);
}

gl_active = 1;

/* The use of strstr here should be safe */
glXext = this->gl_data->glXQueryExtensionsString(GFX_Display, DefaultScreen(GFX_Display));
if ( !SDL_strstr(glXext, "SGI_swap_control") ) {
this->gl_data->glXSwapIntervalSGI = NULL;
}
if ( !SDL_strstr(glXext, "GLX_MESA_swap_control") ) {
this->gl_data->glXSwapIntervalMESA = NULL;
this->gl_data->glXGetSwapIntervalMESA = NULL;
}
if ( this->gl_config.swap_control >= 0 ) {
if ( this->gl_data->glXSwapIntervalMESA ) {
this->gl_data->glXSwapIntervalMESA(this->gl_config.swap_control);
} else if ( this->gl_data->glXSwapIntervalSGI ) {
this->gl_data->glXSwapIntervalSGI(this->gl_config.swap_control);
}
}
#else
SDL_SetError("X11 driver not configured with OpenGL");
#endif
@@ -319,6 +340,13 @@ int X11_GL_GetAttribute(_THIS, SDL_GLattr attrib, int* value)
case SDL_GL_MULTISAMPLESAMPLES:
glx_attrib = GLX_SAMPLES_ARB;
break;
case SDL_GL_SWAP_CONTROL:
if ( this->gl_data->glXGetSwapIntervalMESA ) {
return this->gl_data->glXGetSwapIntervalMESA();
} else {
return -1 /*(this->gl_config.swap_control > 0)*/;
}
break;
default:
return(-1);
}
@@ -348,6 +376,9 @@ void X11_GL_UnloadLibrary(_THIS)
this->gl_data->glXDestroyContext = NULL;
this->gl_data->glXMakeCurrent = NULL;
this->gl_data->glXSwapBuffers = NULL;
this->gl_data->glXSwapIntervalSGI = NULL;
this->gl_data->glXSwapIntervalMESA = NULL;
this->gl_data->glXGetSwapIntervalMESA = NULL;

this->gl_config.dll_handle = NULL;
this->gl_config.driver_loaded = 0;
@@ -400,7 +431,12 @@ int X11_GL_LoadLibrary(_THIS, const char* path)
(int (*)(Display *, XVisualInfo *, int, int *)) SDL_LoadFunction(handle, "glXGetConfig");
this->gl_data->glXQueryExtensionsString =
(const char *(*)(Display *, int)) SDL_LoadFunction(handle, "glXQueryExtensionsString");

this->gl_data->glXSwapIntervalSGI =
(int (*)(int)) SDL_LoadFunction(handle, "glXSwapIntervalSGI");
this->gl_data->glXSwapIntervalMESA =
(GLint (*)(unsigned)) SDL_LoadFunction(handle, "glXSwapIntervalMESA");
this->gl_data->glXGetSwapIntervalMESA =
(GLint (*)(void)) SDL_LoadFunction(handle, "glXGetSwapIntervalMESA");

if ( (this->gl_data->glXChooseVisual == NULL) ||
(this->gl_data->glXCreateContext == NULL) ||
@@ -71,7 +71,10 @@ struct SDL_PrivateGLData {
( Display* dpy,
int screen );


int (*glXSwapIntervalSGI) ( int interval );
GLint (*glXSwapIntervalMESA) ( unsigned interval );
GLint (*glXGetSwapIntervalMESA) ( void );

#endif /* SDL_VIDEO_OPENGL_GLX */
};

@@ -445,7 +445,7 @@ void DrawLogoBlit(void)
}

int RunGLTest( int argc, char* argv[],
int logo, int logocursor, int slowly, int bpp, float gamma, int noframe, int fsaa )
int logo, int logocursor, int slowly, int bpp, float gamma, int noframe, int fsaa, int sync )
{
int i;
int rgb_size[3];
@@ -531,6 +531,11 @@ int RunGLTest( int argc, char* argv[],
SDL_GL_SetAttribute( SDL_GL_MULTISAMPLEBUFFERS, 1 );
SDL_GL_SetAttribute( SDL_GL_MULTISAMPLESAMPLES, fsaa );
}
if ( sync ) {
SDL_GL_SetAttribute( SDL_GL_SWAP_CONTROL, 1 );
} else {
SDL_GL_SetAttribute( SDL_GL_SWAP_CONTROL, 0 );
}
if ( SDL_SetVideoMode( w, h, bpp, video_flags ) == NULL ) {
fprintf(stderr, "Couldn't set GL mode: %s\n", SDL_GetError());
SDL_Quit();
@@ -557,9 +562,13 @@ int RunGLTest( int argc, char* argv[],
printf( "SDL_GL_DOUBLEBUFFER: requested 1, got %d\n", value );
if ( fsaa ) {
SDL_GL_GetAttribute( SDL_GL_MULTISAMPLEBUFFERS, &value );
printf( "SDL_GL_MULTISAMPLEBUFFERS: requested 1, got %d\n", value );
printf("SDL_GL_MULTISAMPLEBUFFERS: requested 1, got %d\n", value );
SDL_GL_GetAttribute( SDL_GL_MULTISAMPLESAMPLES, &value );
printf( "SDL_GL_MULTISAMPLESAMPLES: requested %d, got %d\n", fsaa, value );
printf("SDL_GL_MULTISAMPLESAMPLES: requested %d, got %d\n", fsaa, value );
}
if ( sync ) {
SDL_GL_GetAttribute( SDL_GL_SWAP_CONTROL, &value );
printf( "SDL_GL_SWAP_CONTROL: requested 1, got %d\n", value );
}

/* Set the window manager title bar */
@@ -770,6 +779,7 @@ int main(int argc, char *argv[])
float gamma = 0.0;
int noframe = 0;
int fsaa = 0;
int sync = 0;

logo = 0;
slowly = 0;
@@ -804,6 +814,9 @@ int main(int argc, char *argv[])
if ( strcmp(argv[i], "-fsaa") == 0 ) {
++fsaa;
}
if ( strcmp(argv[i], "-sync") == 0 ) {
++sync;
}
if ( strncmp(argv[i], "-h", 2) == 0 ) {
printf(
"Usage: %s [-twice] [-logo] [-logocursor] [-slow] [-bpp n] [-gamma n] [-noframe] [-fsaa] [-fullscreen]\n",
@@ -812,7 +825,7 @@ int main(int argc, char *argv[])
}
}
for ( i=0; i<numtests; ++i ) {
RunGLTest(argc, argv, logo, logocursor, slowly, bpp, gamma, noframe, fsaa);
RunGLTest(argc, argv, logo, logocursor, slowly, bpp, gamma, noframe, fsaa, sync);
}
return 0;
}

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