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Fixed bug 1565 - some small GL context creation enhancements
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Matthias Bentrup 2012-08-09 12:53:17 PDT

With OpenGL 4.3 the ARB added a new context flag for context reset isolation
and renamed the existing ES2 profile bit to ES profile bit, as it can be used
to request GLES 3 compatible contexts, too.

This patch adds these changes to SDL on Linux and Windows.

Also SDL lacks the ability to create shared contexts. This patch also adds a
new GL attribute to enable context sharing. As casting a GL context to int is
not portable, I added only a boolean attribute
SDL_GL_SHARE_WITH_CURRENT_CONTEXT, which makes the new context share resources
with the context current on the creating thread.
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@slouken
slouken committed Aug 12, 2012
1 parent 2f06d51 commit 1595f24
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Showing 6 changed files with 80 additions and 22 deletions.
7 changes: 5 additions & 2 deletions include/SDL_video.h
View file
Expand Up @@ -185,21 +185,24 @@ typedef enum
SDL_GL_CONTEXT_MINOR_VERSION,
SDL_GL_CONTEXT_EGL,
SDL_GL_CONTEXT_FLAGS,
SDL_GL_CONTEXT_PROFILE_MASK
SDL_GL_CONTEXT_PROFILE_MASK,
SDL_GL_SHARE_WITH_CURRENT_CONTEXT
} SDL_GLattr;

typedef enum
{
SDL_GL_CONTEXT_PROFILE_CORE = 0x0001,
SDL_GL_CONTEXT_PROFILE_COMPATIBILITY = 0x0002,
SDL_GL_CONTEXT_PROFILE_ES = 0x0004,
SDL_GL_CONTEXT_PROFILE_ES2 = 0x0004
} SDL_GLprofile;

typedef enum
{
SDL_GL_CONTEXT_DEBUG_FLAG = 0x0001,
SDL_GL_CONTEXT_FORWARD_COMPATIBLE_FLAG = 0x0002,
SDL_GL_CONTEXT_ROBUST_ACCESS_FLAG = 0x0004
SDL_GL_CONTEXT_ROBUST_ACCESS_FLAG = 0x0004,
SDL_GL_CONTEXT_RESET_ISOLATION_FLAG = 0x0008
} SDL_GLcontextFlag;


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1 change: 1 addition & 0 deletions src/video/SDL_sysvideo.h
View file
Expand Up @@ -280,6 +280,7 @@ struct SDL_VideoDevice
int flags;
int profile_mask;
int use_egl;
int share_with_current_context;
int retained_backing;
int driver_loaded;
char driver_path[256];
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25 changes: 25 additions & 0 deletions src/video/SDL_video.c
View file
Expand Up @@ -505,6 +505,7 @@ SDL_VideoInit(const char *driver_name)
#endif
_this->gl_config.flags = 0;
_this->gl_config.profile_mask = 0;
_this->gl_config.share_with_current_context = 0;

/* Initialize the video subsystem */
if (_this->VideoInit(_this) < 0) {
Expand Down Expand Up @@ -2309,11 +2310,30 @@ SDL_GL_SetAttribute(SDL_GLattr attr, int value)
_this->gl_config.use_egl = value;
break;
case SDL_GL_CONTEXT_FLAGS:
if( value & ~(SDL_GL_CONTEXT_DEBUG_FLAG |
SDL_GL_CONTEXT_FORWARD_COMPATIBLE_FLAG |
SDL_GL_CONTEXT_ROBUST_ACCESS_FLAG |
SDL_GL_CONTEXT_RESET_ISOLATION_FLAG) ) {
SDL_SetError("Unknown OpenGL context flag %d", value);
retval = -1;
break;
}
_this->gl_config.flags = value;
break;
case SDL_GL_CONTEXT_PROFILE_MASK:
if( value != 0 &&
value != SDL_GL_CONTEXT_PROFILE_CORE &&
value != SDL_GL_CONTEXT_PROFILE_COMPATIBILITY &&
value != SDL_GL_CONTEXT_PROFILE_ES ) {
SDL_SetError("Unknown OpenGL context profile %d", value);
retval = -1;
break;
}
_this->gl_config.profile_mask = value;
break;
case SDL_GL_SHARE_WITH_CURRENT_CONTEXT:
_this->gl_config.share_with_current_context = value;
break;
default:
SDL_SetError("Unknown OpenGL attribute");
retval = -1;
Expand Down Expand Up @@ -2475,6 +2495,11 @@ SDL_GL_GetAttribute(SDL_GLattr attr, int *value)
*value = _this->gl_config.profile_mask;
return 0;
}
case SDL_GL_SHARE_WITH_CURRENT_CONTEXT:
{
*value = _this->gl_config.share_with_current_context;
return 0;
}
default:
SDL_SetError("Unknown OpenGL attribute");
return -1;
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25 changes: 22 additions & 3 deletions src/video/windows/SDL_windowsopengl.c
View file
Expand Up @@ -61,6 +61,11 @@
#define WGL_CONTEXT_ES2_PROFILE_BIT_EXT 0x00000004
#endif

#ifndef WGL_EXT_create_context_es_profile
#define WGL_EXT_create_context_es_profile
#define WGL_CONTEXT_ES_PROFILE_BIT_EXT 0x00000004
#endif

typedef HGLRC(APIENTRYP PFNWGLCREATECONTEXTATTRIBSARBPROC) (HDC hDC,
HGLRC
hShareContext,
Expand Down Expand Up @@ -112,6 +117,8 @@ WIN_GL_LoadLibrary(_THIS, const char *path)
GetProcAddress(handle, "wglDeleteContext");
_this->gl_data->wglMakeCurrent = (BOOL(WINAPI *) (HDC, HGLRC))
GetProcAddress(handle, "wglMakeCurrent");
_this->gl_data->wglShareLists = (BOOL(WINAPI *) (HGLRC, HGLRC))
GetProcAddress(handle, "wglShareLists");

if (!_this->gl_data->wglGetProcAddress ||
!_this->gl_data->wglCreateContext ||
Expand Down Expand Up @@ -519,10 +526,22 @@ SDL_GLContext
WIN_GL_CreateContext(_THIS, SDL_Window * window)
{
HDC hdc = ((SDL_WindowData *) window->driverdata)->hdc;
HGLRC context;
HGLRC context, share_context;

if (_this->gl_config.share_with_current_context) {
share_context = (HGLRC)(_this->current_glctx);
} else {
share_context = 0;
}

if (_this->gl_config.major_version < 3) {
if (_this->gl_config.major_version < 3 &&
_this->gl_config.profile_mask == 0 &&
_this->gl_config.flags == 0) {
/* Create legacy context */
context = _this->gl_data->wglCreateContext(hdc);
if( share_context != 0 ) {
_this->gl_data->wglShareLists(share_context, hdc);
}
} else {
PFNWGLCREATECONTEXTATTRIBSARBPROC wglCreateContextAttribsARB;
HGLRC temp_context = _this->gl_data->wglCreateContext(hdc);
Expand Down Expand Up @@ -567,7 +586,7 @@ WIN_GL_CreateContext(_THIS, SDL_Window * window)
attribs[iattr++] = 0;

/* Create the GL 3.x context */
context = wglCreateContextAttribsARB(hdc, 0, attribs);
context = wglCreateContextAttribsARB(hdc, share_context, attribs);
/* Delete the GL 2.x context */
_this->gl_data->wglDeleteContext(temp_context);
}
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1 change: 1 addition & 0 deletions src/video/windows/SDL_windowsopengl.h
View file
Expand Up @@ -34,6 +34,7 @@ struct SDL_GLDriverData
HGLRC(WINAPI * wglCreateContext) (HDC hdc);
BOOL(WINAPI * wglDeleteContext) (HGLRC hglrc);
BOOL(WINAPI * wglMakeCurrent) (HDC hdc, HGLRC hglrc);
BOOL(WINAPI * wglShareLists) (HGLRC hglrc1, HGLRC hglrc2);
BOOL(WINAPI * wglChoosePixelFormatARB) (HDC hdc,
const int *piAttribIList,
const FLOAT * pfAttribFList,
Expand Down
43 changes: 26 additions & 17 deletions src/video/x11/SDL_x11opengl.c
View file
Expand Up @@ -484,7 +484,13 @@ X11_GL_CreateContext(_THIS, SDL_Window * window)
XWindowAttributes xattr;
XVisualInfo v, *vinfo;
int n;
GLXContext context = NULL;
GLXContext context = NULL, share_context;

if (_this->gl_config.share_with_current_context) {
share_context = (GLXContext)(_this->current_glctx);
} else {
share_context = NULL;
}

/* We do this to create a clean separation between X and GLX errors. */
XSync(display, False);
Expand All @@ -493,9 +499,12 @@ X11_GL_CreateContext(_THIS, SDL_Window * window)
v.visualid = XVisualIDFromVisual(xattr.visual);
vinfo = XGetVisualInfo(display, VisualScreenMask | VisualIDMask, &v, &n);
if (vinfo) {
if (_this->gl_config.major_version < 3) {
if (_this->gl_config.major_version < 3 &&
_this->gl_config.profile_mask == 0 &&
_this->gl_config.flags == 0) {
/* Create legacy context */
context =
_this->gl_data->glXCreateContext(display, vinfo, NULL, True);
_this->gl_data->glXCreateContext(display, vinfo, share_context, True);
} else {
/* If we want a GL 3.0 context or later we need to get a temporary
context to grab the new context creation function */
Expand All @@ -505,29 +514,29 @@ X11_GL_CreateContext(_THIS, SDL_Window * window)
SDL_SetError("Could not create GL context");
return NULL;
} else {
/* max 8 attributes plus terminator */
/* max 8 attributes plus terminator */
int attribs[9] = {
GLX_CONTEXT_MAJOR_VERSION_ARB,
_this->gl_config.major_version,
GLX_CONTEXT_MINOR_VERSION_ARB,
_this->gl_config.minor_version,
0
};
int iattr = 4;
int iattr = 4;

/* SDL profile bits match GLX profile bits */
if( _this->gl_config.profile_mask != 0 ) {
attribs[iattr++] = GLX_CONTEXT_PROFILE_MASK_ARB;
attribs[iattr++] = _this->gl_config.profile_mask;
}
/* SDL profile bits match GLX profile bits */
if( _this->gl_config.profile_mask != 0 ) {
attribs[iattr++] = GLX_CONTEXT_PROFILE_MASK_ARB;
attribs[iattr++] = _this->gl_config.profile_mask;
}

/* SDL flags match GLX flags */
if( _this->gl_config.flags != 0 ) {
attribs[iattr++] = GLX_CONTEXT_FLAGS_ARB;
attribs[iattr++] = _this->gl_config.flags;
}
/* SDL flags match GLX flags */
if( _this->gl_config.flags != 0 ) {
attribs[iattr++] = GLX_CONTEXT_FLAGS_ARB;
attribs[iattr++] = _this->gl_config.flags;
}

attribs[iattr++] = 0;
attribs[iattr++] = 0;

/* Get a pointer to the context creation function for GL 3.0 */
PFNGLXCREATECONTEXTATTRIBSARBPROC glXCreateContextAttribs =
Expand Down Expand Up @@ -568,7 +577,7 @@ X11_GL_CreateContext(_THIS, SDL_Window * window)
context =
glXCreateContextAttribs(display,
framebuffer_config[0],
NULL, True, attribs);
share_context, True, attribs);
_this->gl_data->glXDestroyContext(display,
temp_context);
}
Expand Down

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