On Tue, Sep 16, 2014 at 6:41 PM, Ilia Mirkin <imir...@alum.mit.edu> wrote: > On Tue, Sep 16, 2014 at 12:29 PM, Marek Olšák <mar...@gmail.com> wrote: >> On Tue, Sep 16, 2014 at 5:42 PM, Ilia Mirkin <imir...@alum.mit.edu> wrote: >>> OK, so just to summarize: >>> >>> The approach suggested by Roland is to have the outputs be >>> one-dimensional and only representing the current invocation's >>> per-vertex outputs. Each invocation would also get access to other >>> invocations' per-vertex outputs via a 2d input array. >>> >>> So a shader might look something like >>> >>> TESSC >>> DECL IN[][0], POSITION (input patch's per-vertex position) >>> DECL IN[][1], GENERIC (input patch's per-vertex generic attribute) >>> DECL IN[][2], TCS_POSITION (output patch's per-vertex position) >>> DECL IN[][3], TCS_OUTPUT (output patch's per-vertex generic attribute) >>> DECL OUT[0], POSITION >>> DECL OUT[1], GENERIC >>> DECL OUT[2], PATCH >>> >>> And then anything written to OUT[0] would be aliased via IN[][2]. >>> Roland, does that sound right? This seems kinda nasty that there are >>> going to be 2 types of position/pointsize/clipdistance inputs -- do >>> you have a better suggestion for handling that? >> >> The output-as-input arrays can be declared as system values (SV), then >> you don't need to duplicate semantic names. > > OK, that sounds reasonable. And what do you guys think about reading > directly from per-patch outputs? Or should they also be mirrored as > SV's? We definitely need something since it's shared between > invocations and synchronizable using barrier.
Alternatively, you can add another TGSI file for these kinds of variables. I personally don't care much as long as it doesn't get messy. I'll probably use on-chip shared memory for the outputs and load/store instructions for accessing them, so if they are inputs or outputs in TGSI doesn't make much difference for me. Marek _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
