[Mesa-dev] [PATCH 2/3] st/mesa: set force_persample_interp if ARB_sample_shading is used

[Marek Olšák]

From: Marek Olšák <marek.olsak at amd.com>

This is only a half of the work. The next patch will handle
gl_SampleID/SamplePos, which is the other half of ARB_sample_shading.
---
 src/mesa/state_tracker/st_atom_rasterizer.c | 8 ++++++++
 src/mesa/state_tracker/st_atom_shader.c     | 1 +
 src/mesa/state_tracker/st_context.c         | 2 ++
 src/mesa/state_tracker/st_context.h         | 1 +
 4 files changed, 12 insertions(+)

diff --git a/src/mesa/state_tracker/st_atom_rasterizer.c b/src/mesa/state_tracker/st_atom_rasterizer.c
index cceed42..3a9c461 100644
--- a/src/mesa/state_tracker/st_atom_rasterizer.c
+++ b/src/mesa/state_tracker/st_atom_rasterizer.c
@@ -237,6 +237,14 @@ static void update_raster_state( struct st_context *st )
    /* _NEW_MULTISAMPLE */
    raster->multisample = ctx->Multisample._Enabled;
 
+   /* _NEW_MULTISAMPLE | _NEW_BUFFERS */
+   raster->force_persample_interp =
+         st->can_force_persample_interp &&
+         ctx->Multisample._Enabled &&
+         ctx->Multisample.SampleShading &&
+         MAX2(ceil(ctx->Multisample.MinSampleShadingValue *
+                   ctx->DrawBuffer->Visual.samples), 1) > 1;
+
    /* _NEW_SCISSOR */
    raster->scissor = ctx->Scissor.EnableFlags;
 
diff --git a/src/mesa/state_tracker/st_atom_shader.c b/src/mesa/state_tracker/st_atom_shader.c
index fee15a9..dc03156 100644
--- a/src/mesa/state_tracker/st_atom_shader.c
+++ b/src/mesa/state_tracker/st_atom_shader.c
@@ -72,6 +72,7 @@ update_fp( struct st_context *st )
 
    /* Ignore sample qualifier while computing this flag. */
    key.persample_shading =
+      !st->can_force_persample_interp &&
       _mesa_get_min_invocations_per_fragment(st->ctx, &stfp->Base, true) > 1;
 
    st->fp_variant = st_get_fp_variant(st, stfp, &key);
diff --git a/src/mesa/state_tracker/st_context.c b/src/mesa/state_tracker/st_context.c
index 72c23ca..7061191 100644
--- a/src/mesa/state_tracker/st_context.c
+++ b/src/mesa/state_tracker/st_context.c
@@ -237,6 +237,8 @@ st_create_context_priv( struct gl_context *ctx, struct pipe_context *pipe,
                                               PIPE_BIND_SAMPLER_VIEW);
    st->prefer_blit_based_texture_transfer = screen->get_param(screen,
                               PIPE_CAP_PREFER_BLIT_BASED_TEXTURE_TRANSFER);
+   st->can_force_persample_interp = screen->get_param(screen,
+                                          PIPE_CAP_FORCE_PERSAMPLE_INTERP);
 
    st->needs_texcoord_semantic =
       screen->get_param(screen, PIPE_CAP_TGSI_TEXCOORD);
diff --git a/src/mesa/state_tracker/st_context.h b/src/mesa/state_tracker/st_context.h
index 81d5480..a4cda29 100644
--- a/src/mesa/state_tracker/st_context.h
+++ b/src/mesa/state_tracker/st_context.h
@@ -98,6 +98,7 @@ struct st_context
    boolean has_etc1;
    boolean has_etc2;
    boolean prefer_blit_based_texture_transfer;
+   boolean can_force_persample_interp;
 
    boolean needs_texcoord_semantic;
    boolean apply_texture_swizzle_to_border_color;
-- 
2.1.4