[Mesa-dev] [Mesa-stable] [PATCH 3/3] i965: Fix component mask and varying_to_slot mapping for gl_ViewportIndex

[Chris Forbes]

Are the streamout values allowed to be restricted to the ranges of the
vertex header fields, or do they have to reflect exactly what the
shader wrote?

(I ran into a similar issue with ARB_fragment_layer_viewport, and
while nothing has been done about it, the consensus was that the FS
had to see exactly what the previous stage wrote, and so a real slot
would be necessary)

On Tue, Apr 15, 2014 at 11:23 AM, Anuj Phogat <anuj.phogat at gmail.com> wrote:
> gl_ViewportIndex doesn't get its own varying slot. It is stored
> in VARYING_SLOT_PSIZ.z. This patch fixes the issue for both gen7
> and gen8 because gen7_upload_3dstate_so_decl_list() is shared
> between them.
>
> Fixes failures in OpenGL Khronos CTS test transform_feedback_builtins.
> Makes new piglit test glsl-1.50-transform-feedback-builtins pass for
> 'gl_ViewportIndex'.
>
> Cc: <mesa-stable at lists.freedesktop.org>
> Signed-off-by: Anuj Phogat <anuj.phogat at gmail.com>
> ---
>  src/mesa/drivers/dri/i965/gen7_sol_state.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/src/mesa/drivers/dri/i965/gen7_sol_state.c b/src/mesa/drivers/dri/i965/gen7_sol_state.c
> index 3623238..8e554af 100644
> --- a/src/mesa/drivers/dri/i965/gen7_sol_state.c
> +++ b/src/mesa/drivers/dri/i965/gen7_sol_state.c
> @@ -123,6 +123,7 @@ gen7_upload_3dstate_so_decl_list(struct brw_context *brw,
>
>        /* gl_PointSize is stored in VARYING_SLOT_PSIZ.w
>         * gl_Layer is stored in VARYING_SLOT_PSIZ.y
> +       * gl_ViewportIndex is stored in VARYING_SLOT_PSIZ.z
>         */
>        if (varying == VARYING_SLOT_PSIZ) {
>           assert(components == 1);
> @@ -130,6 +131,9 @@ gen7_upload_3dstate_so_decl_list(struct brw_context *brw,
>        } else if (varying == VARYING_SLOT_LAYER) {
>           assert(components == 1);
>           component_mask <<= 1;
> +      } else if (varying == VARYING_SLOT_VIEWPORT) {
> +         assert(components == 1);
> +         component_mask <<= 2;
>        } else {
>           component_mask <<= linked_xfb_info->Outputs[i].ComponentOffset;
>        }
> @@ -137,7 +141,7 @@ gen7_upload_3dstate_so_decl_list(struct brw_context *brw,
>        buffer_mask |= 1 << buffer;
>
>        decl |= buffer << SO_DECL_OUTPUT_BUFFER_SLOT_SHIFT;
> -      if (varying == VARYING_SLOT_LAYER) {
> +      if (varying == VARYING_SLOT_LAYER || varying == VARYING_SLOT_VIEWPORT) {
>           decl |= vue_map->varying_to_slot[VARYING_SLOT_PSIZ] <<
>              SO_DECL_REGISTER_INDEX_SHIFT;
>        } else {
> --
> 1.8.3.1
>
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