Commit ece8d2bb056aad9f6937509abae636effb053fc0
2015-02-02T01:05:41
X11: Fixes for OpenGL 3.0 and later context creation. - Don't create a temporary context first; this was probably due to Windows needing one to get the address of wglCreateContextAttribsARB(), but that's a unique quirk of WGL, and doesn't apply to glX. The glX spec explicitly says you have to get a function pointer that works with any context from glXGetProcAddress(), including when no context exists. - Properly check for the GLX_ARB_create_context instead of just looking for a non-NULL glXCreateContextAttribsARB()...some implementations, like Mesa, never return NULL for function lookups (Mesa returns pointers into a jump table that is filled out when the GL is initialized; since you can look up functions before you have a valid context, it can't definitely say a function isn't valid at that point).
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diff --git a/src/video/x11/SDL_x11opengl.c b/src/video/x11/SDL_x11opengl.c
index 1e94b04..c46710f 100644
--- a/src/video/x11/SDL_x11opengl.c
+++ b/src/video/x11/SDL_x11opengl.c
@@ -373,6 +373,16 @@ X11_GL_InitExtensions(_THIS)
(int (*)(int)) X11_GL_GetProcAddress(_this, "glXSwapIntervalSGI");
}
+ /* Check for GLX_ARB_create_context */
+ if (HasExtension("GLX_ARB_create_context", extensions)) {
+ _this->gl_data->glXCreateContextAttribsARB =
+ (GLXContext (*)(Display*,GLXFBConfig,GLXContext,Bool,const int *))
+ X11_GL_GetProcAddress(_this, "glXCreateContextAttribsARB");
+ _this->gl_data->glXChooseFBConfig =
+ (GLXFBConfig *(*)(Display *, int, const int *, int *))
+ X11_GL_GetProcAddress(_this, "glXChooseFBConfig");
+ }
+
/* Check for GLX_EXT_visual_rating */
if (HasExtension("GLX_EXT_visual_rating", extensions)) {
_this->gl_data->HAS_GLX_EXT_visual_rating = SDL_TRUE;
@@ -576,7 +586,6 @@ X11_GL_CreateContext(_THIS, SDL_Window * window)
XVisualInfo v, *vinfo;
int n;
GLXContext context = NULL, share_context;
- PFNGLXCREATECONTEXTATTRIBSARBPROC glXCreateContextAttribs = NULL;
if (_this->gl_config.share_with_current_context) {
share_context = (GLXContext)SDL_GL_GetCurrentContext();
@@ -601,78 +610,52 @@ X11_GL_CreateContext(_THIS, SDL_Window * window)
context =
_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 */
- GLXContext temp_context =
- _this->gl_data->glXCreateContext(display, vinfo, NULL, True);
- if (temp_context) {
- /* 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;
-
- /* 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;
- }
+ /* 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;
+
+ /* 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;
+
+ /* Get a pointer to the context creation function for GL 3.0 */
+ if (!_this->gl_data->glXCreateContextAttribsARB) {
+ SDL_SetError("OpenGL 3.0 and later are not supported by this system");
+ } else {
+ int glxAttribs[64];
+
+ /* Create a GL 3.x context */
+ GLXFBConfig *framebuffer_config = NULL;
+ int fbcount = 0;
- attribs[iattr++] = 0;
+ X11_GL_GetAttributes(_this,display,screen,glxAttribs,64,SDL_TRUE);
- /* Get a pointer to the context creation function for GL 3.0 */
- glXCreateContextAttribs =
- (PFNGLXCREATECONTEXTATTRIBSARBPROC) _this->gl_data->
- glXGetProcAddress((GLubyte *)
- "glXCreateContextAttribsARB");
- if (!glXCreateContextAttribs) {
- SDL_SetError("GL 3.x is not supported");
- context = temp_context;
+ if (!_this->gl_data->glXChooseFBConfig
+ || !(framebuffer_config =
+ _this->gl_data->glXChooseFBConfig(display,
+ DefaultScreen(display), glxAttribs,
+ &fbcount))) {
+ SDL_SetError("No good framebuffers found. OpenGL 3.0 and later unavailable");
} else {
- int glxAttribs[64];
-
- /* Create a GL 3.x context */
- GLXFBConfig *framebuffer_config = NULL;
- int fbcount = 0;
- GLXFBConfig *(*glXChooseFBConfig) (Display * disp,
- int screen,
- const int *attrib_list,
- int *nelements);
-
- glXChooseFBConfig =
- (GLXFBConfig *
- (*)(Display *, int, const int *,
- int *)) _this->gl_data->
- glXGetProcAddress((GLubyte *) "glXChooseFBConfig");
-
- X11_GL_GetAttributes(_this,display,screen,glxAttribs,64,SDL_TRUE);
-
- if (!glXChooseFBConfig
- || !(framebuffer_config =
- glXChooseFBConfig(display,
- DefaultScreen(display), glxAttribs,
- &fbcount))) {
- SDL_SetError
- ("No good framebuffers found. GL 3.x disabled");
- context = temp_context;
- } else {
- context =
- glXCreateContextAttribs(display,
+ context = _this->gl_data->glXCreateContextAttribsARB(display,
framebuffer_config[0],
share_context, True, attribs);
- _this->gl_data->glXDestroyContext(display,
- temp_context);
- }
}
}
}
diff --git a/src/video/x11/SDL_x11opengl.h b/src/video/x11/SDL_x11opengl.h
index ed7f292..b3410fd 100644
--- a/src/video/x11/SDL_x11opengl.h
+++ b/src/video/x11/SDL_x11opengl.h
@@ -40,6 +40,8 @@ struct SDL_GLDriverData
void *(*glXGetProcAddress) (const GLubyte*);
XVisualInfo *(*glXChooseVisual) (Display*,int,int*);
GLXContext (*glXCreateContext) (Display*,XVisualInfo*,GLXContext,Bool);
+ GLXContext (*glXCreateContextAttribsARB) (Display*,GLXFBConfig,GLXContext,Bool,const int *);
+ GLXFBConfig *(*glXChooseFBConfig) (Display*,int,const int *,int *);
void (*glXDestroyContext) (Display*, GLXContext);
Bool(*glXMakeCurrent) (Display*,GLXDrawable,GLXContext);
void (*glXSwapBuffers) (Display*, GLXDrawable);