Fixed bug 1161 (Setting GL_ACCELERATED_VISUAL to 1 forces software re…

…ndering in Windows XP) Jesse Anders 2011-03-05 23:30:09 PST It seems that in Windows XP, setting SDL_GL_ACCELERATED_VISUAL to 1 actually disables hardware acceleration and puts OpenGL in software mode. In the source code, the corresponding WGL attribute is first set here: *iAttr++ = WGL_ACCELERATION_ARB; *iAttr++ = WGL_FULL_ACCELERATION_ARB; Later, this code: if (_this->gl_config.accelerated >= 0) { *iAttr++ = WGL_ACCELERATION_ARB; *iAttr++ = (_this->gl_config.accelerated ? WGL_GENERIC_ACCELERATION_ARB : WGL_NO_ACCELERATION_ARB); } Sets it again if SDL_GL_ACCELERATED_VISUAL has a value other than the default. More importantly, the documentation I found states that WGL_GENERIC_ACCELERATION_ARB asks for an MDC driver, which, although I don't know much about this topic, doesn't seem like the correct choice here. As mentioned previously, the end effect is that requesting hardware acceleration in Windows XP actually forces the renderer into software mode (on my system at least), which I'm guessing isn't the desired behavior.
libsdl-org · Mar 7, 2011 · 32c3182 · 32c3182
1 parent bbb2ead
commit 32c3182
Showing 1 changed file with 3 additions and 8 deletions.
diff --git a/src/video/windows/SDL_windowsopengl.c b/src/video/windows/SDL_windowsopengl.c
@@ -409,8 +409,6 @@ WIN_GL_SetupWindow(_THIS, SDL_Window * window)
 
     *iAttr++ = WGL_DRAW_TO_WINDOW_ARB;
     *iAttr++ = GL_TRUE;
-    *iAttr++ = WGL_ACCELERATION_ARB;
-    *iAttr++ = WGL_FULL_ACCELERATION_ARB;
     *iAttr++ = WGL_RED_BITS_ARB;
     *iAttr++ = _this->gl_config.red_size;
     *iAttr++ = WGL_GREEN_BITS_ARB;
@@ -469,12 +467,9 @@ WIN_GL_SetupWindow(_THIS, SDL_Window * window)
         *iAttr++ = _this->gl_config.multisamplesamples;
     }
 
-    if (_this->gl_config.accelerated >= 0) {
-        *iAttr++ = WGL_ACCELERATION_ARB;
-        *iAttr++ =
-            (_this->gl_config.accelerated ? WGL_GENERIC_ACCELERATION_ARB :
-             WGL_NO_ACCELERATION_ARB);
-    }
+    *iAttr++ = WGL_ACCELERATION_ARB;
+    *iAttr++ = (_this->gl_config.accelerated ? WGL_FULL_ACCELERATION_ARB :
+                                               WGL_NO_ACCELERATION_ARB);
 
     *iAttr = 0;