st/mesa: do vertex and fragment color clamping in shaders

For ARB_color_buffer_float. Most hardware can't do it and st/mesa is
the perfect place for a fallback.
The exceptions are:
- r500 (vertex clamp only)
- nv50 (both)
- nvc0 (both)
- softpipe (both)

We also have to take into account that r300 can do CLAMPED vertex colors only,
while r600 can do UNCLAMPED vertex colors only. The difference can be expressed
with the two new CAPs.

1 files changed, 4 insertions, 2 deletions

diff --git a/src/mesa/state_tracker/st_atom_rasterizer.c b/src/mesa/state_tracker/st_atom_rasterizer.c
index f3d28e675f5..25799bf2bd5 100644
--- a/src/mesa/state_tracker/st_atom_rasterizer.c
+++ b/src/mesa/state_tracker/st_atom_rasterizer.c
@@ -112,7 +112,8 @@ static void update_raster_state( struct st_context *st )
       raster->light_twoside = 1;
    }
 
-   raster->clamp_vertex_color = ctx->Light._ClampVertexColor;
+   raster->clamp_vertex_color = !st->clamp_vert_color_in_shader &&
+                                ctx->Light._ClampVertexColor;
 
    /* _NEW_POLYGON
     */
@@ -255,7 +256,8 @@ static void update_raster_state( struct st_context *st )
       raster->scissor = 1;
 
    /* _NEW_FRAG_CLAMP */
-   raster->clamp_fragment_color = ctx->Color._ClampFragmentColor;
+   raster->clamp_fragment_color = !st->clamp_frag_color_in_shader &&
+                                  ctx->Color._ClampFragmentColor;
    raster->gl_rasterization_rules = 1;
 
    /* _NEW_RASTERIZER_DISCARD */