On Tue, Sep 9, 2014 at 7:30 PM, Ian Romanick <i...@freedesktop.org> 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.
Historical note: It's not broken, this is by design. The rationale for why we did this was to ease the burden of compile-time checks for the compiler - detecting if gl_Position is written no matter how the program branches is not trivial, so we decided against it. When we specified this, the typical mobile CPU clock-rate was *a lot* lower than it is today. Sure, it probably could have been fixed for GLES 3.0. I wasn't involved in those discussions, so I have no insight there. _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
