st/mesa: set force_persample_interp if ARB_sample_shading is used

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.

Reviewed-by: Ilia Mirkin <[email protected]>

1 files changed, 8 insertions, 0 deletions

diff --git a/src/mesa/state_tracker/st_atom_rasterizer.c b/src/mesa/state_tracker/st_atom_rasterizer.c
index cceed42c828..0f01e9939de 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 &&
+         ctx->Multisample.MinSampleShadingValue *
+         ctx->DrawBuffer->Visual.samples > 1;
+
    /* _NEW_SCISSOR */
    raster->scissor = ctx->Scissor.EnableFlags;