On 09/09/2014 11:54 AM, Marek Olšák wrote: > On Tue, Sep 9, 2014 at 8:26 PM, Kenneth Graunke <kenn...@whitecape.org> wrote: >> On Tuesday, September 09, 2014 10:30:16 AM Ian Romanick wrote: >>> On 09/08/2014 01:10 AM, Tapani Pälli wrote: >>>> From: Kalyan Kondapally <kalyan.kondapa...@intel.com> >>>> >>>> According to GLSL-ES Spec(i.e. 1.0, 3.0), gl_Position value is undefined >>>> after the vertex processing stage if we don't write gl_Position. However, >>>> GLSL 1.10 Spec mentions that writing to gl_Position is mandatory. In case >>>> of GLSL-ES, it's not an error and atleast the linking should pass. >>>> Currently, Mesa throws an linker error in case we dont write to gl_position >>>> and Version is less then 140(GLSL) and 300(GLSL-ES). This patch changes >>>> it so that we don't report an error in case of GLSL-ES. >>> >>> Wow. We can add this to the list of ways OpenGL ES is just plain >>> broken. Since there is absolutely NO WAY this shader can produce any >>> useful results, we should at least do the courtesy of generating a >>> warning. So, keep the first if-condistion the same, but do >>> linker_warning instead of linker_error if prog->IsES. >> >> I like that idea. But what about 1.40 or 1.50? I'm having a hard time >> imagining how 1.40 would let you produce any useful results, either (so >> maybe we should issue a warning there too). With 1.50, you at least have >> geometry shaders, so you can produce real output later... > > If you are using transform feedback or store instructions with > rasterization disabled, gl_Position is useless.
And that is why the restriction was lifted in 1.40. Though... now I wonder about using GL_EXT_transform_feedback with earlier shader versions.... > Marek > _______________________________________________ > mesa-dev mailing list > mesa-dev@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/mesa-dev _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
