<div dir="ltr">On 19 December 2012 12:21, Chad Versace <<a href="mailto:chad.versace@linux.intel.com" target="_blank">chad.versace@linux.intel.com</a>> wrote: <div class="gmail_extra"><div class="gmail_quote"> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">With NVidia, calling glXCreateContextAttribsARB with MAJOR=1 and MINOR=0 returns an OpenGL 2.1 context. Calling it with MAJOR and MINOR unspecified returns a context of the latest supported OpenGL version. However, according to the GLX_ARB_create_context spec, the two calls should behave identically. Calling with MAJOR and MINOR unspecified produces the expected behavior. As a workaround, do not specify GLX_CONTEXT_MAJOR_VERSION_ARB and GLX_CONTEXT_MINOR_VERSION_ARB in the call to glXCreateContextAttribsARB if the user requested an OpenGL context of unspecified version or if the user explicitly requested an OpenGL 1.0 context. Reported-by: Paul Berry <<a href="mailto:stereotype441@gmail.com">stereotype441@gmail.com</a>> Signed-off-by: Chad Versace <<a href="mailto:chad.versace@linux.intel.com">chad.versace@linux.intel.com</a>> </blockquote><div> </div><div>Reviewed-and-tested-by: Paul Berry <<a href="mailto:stereotype441@gmail.com">stereotype441@gmail.com</a>>. </div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> --- src/waffle/glx/glx_context.c | 37 ++++++++++++++++++++++++++++++++----- 1 file changed, 32 insertions(+), 5 deletions(-) diff --git a/src/waffle/glx/glx_context.c b/src/waffle/glx/glx_context.c index bc218af..ffb79a4 100644 --- a/src/waffle/glx/glx_context.c +++ b/src/waffle/glx/glx_context.c @@ -72,11 +72,38 @@ glx_context_fill_attrib_list(struct glx_config *config, struct wcore_config_attrs *attrs = &config->wcore.attrs; int i = 0; - attrib_list[i++] = GLX_CONTEXT_MAJOR_VERSION_ARB; - attrib_list[i++] = attrs->context_major_version; - - attrib_list[i++] = GLX_CONTEXT_MINOR_VERSION_ARB; - attrib_list[i++] = attrs->context_minor_version; + // As a workaround for NVidia, do not specify + // GLX_CONTEXT_MAJOR_VERSION_ARB and GLX_CONTEXT_MINOR_VERSION_ARB in the + // call to glXCreateContextAttribsARB if the user requested an OpenGL + // context of unspecified version or if the user explicitly requested an + // OpenGL 1.0 context. + // + // Calling glXCreateContextAttribARB with MAJOR=1 and MINOR=0, according + // to the spec, is equivalent to calling it with MAJOR and MINOR + // unspecified. From the GLX_ARB_create_context spec: + // + // If an attribute is not specified in <attrib_list>, + // then the default value specified below is used instead. + // + // The default values for GLX_CONTEXT_MAJOR_VERSION_ARB and + // GLX_CONTEXT_MINOR_VERSION_ARB are 1 and 0 respectively. In this + // case, implementations will typically return the most recent version + // of OpenGL they support which is backwards compatible with OpenGL 1.0 + // (e.g. 3.0, 3.1 + GL_ARB_compatibility, or 3.2 compatibility profile) + // + // However, NVidia's libGL, circa 2012-12-19, is not compliant. Calling + // glXCreateContextAttribsARB with MAJOR=1 and MINOR=0 returns an OpenGL + // 2.1 context. Calling it with MAJOR and MINOR unspecified returns + // a context of the latest supported OpenGL version. + if (attrs->context_api == WAFFLE_CONTEXT_OPENGL && + attrs->context_full_version != 10) + { + attrib_list[i++] = GLX_CONTEXT_MAJOR_VERSION_ARB; + attrib_list[i++] = attrs->context_major_version; + + attrib_list[i++] = GLX_CONTEXT_MINOR_VERSION_ARB; + attrib_list[i++] = attrs->context_minor_version; + } switch (attrs->context_api) { case WAFFLE_CONTEXT_OPENGL: -- 1.7.11.7 </blockquote></div> </div></div>