gallium: Enable ARB_clip_control for gallium drivers.

Gallium should be prepared fine for ARB_clip_control.
So enable this and mention it in the release notes.

v2:
Only enable for drivers announcing the freshly introduced
PIPE_CAP_CLIP_HALFZ capability.

v3:
Use extension enable infrastructure to connect PIPE_CAP_CLIP_HALFZ
with ARB_clip_control.

Reviewed-by: Brian Paul <brianp@vmware.com>
Signed-off-by: Mathias Froehlich <Mathias.Froehlich@web.de>

docs/GL3.txt

@@ -187,7 +187,7 @@ GL 4.4, GLSL 4.40:
 GL 4.5, GLSL 4.50:
 
   GL_ARB_ES3_1_compatibility                           not started
-  GL_ARB_clip_control                                  not started
+  GL_ARB_clip_control                                  DONE (llvmpipe, softpipe, r300, r600, radeonsi)
   GL_ARB_conditional_render_inverted                   DONE (i965, nvc0, llvmpipe, softpipe)
   GL_ARB_cull_distance                                 not started
   GL_ARB_derivative_control                            DONE (i965, nv50, nvc0, r600)

docs/relnotes/10.4.html

@@ -46,6 +46,7 @@ Note: some of the new features are only available with certain drivers.
 <ul>
 <li>GL_ARB_sample_shading on r600</li>
 <li>GL_ARB_texture_view on nv50, nvc0</li>
+<li>GL_ARB_clip_control on llvmpipe, softpipe, r300, r600, radeonsi</li>
 </ul>
 
 

src/mesa/state_tracker/st_atom_rasterizer.c

@@ -72,6 +72,11 @@ static void update_raster_state( struct st_context *st )
    {
       raster->front_ccw = (ctx->Polygon.FrontFace == GL_CCW);
 
+      /* _NEW_VIEWPORT */
+      if (ctx->Transform.ClipOrigin == GL_UPPER_LEFT) {
+         raster->front_ccw ^= 1;
+      }
+
       /*
        * Gallium's surfaces are Y=0=TOP orientation.  OpenGL is the
        * opposite.  Window system surfaces are Y=0=TOP.  Mesa's FBOs
@@ -241,6 +246,12 @@ static void update_raster_state( struct st_context *st )
    raster->half_pixel_center = 1;
    if (st_fb_orientation(ctx->DrawBuffer) == Y_0_TOP)
       raster->bottom_edge_rule = 1;
+   /* _NEW_VIEWPORT */
+   if (ctx->Transform.ClipOrigin == GL_UPPER_LEFT)
+      raster->bottom_edge_rule ^= 1;
+
+   /* _NEW_VIEWPORT */
+   raster->clip_halfz = (ctx->Transform.ClipDepthMode == GL_ZERO_TO_ONE);
 
    /* ST_NEW_RASTERIZER */
    raster->rasterizer_discard = ctx->RasterDiscard;
@@ -272,7 +283,8 @@ const struct st_tracked_state st_update_rasterizer = {
        _NEW_PROGRAM |
        _NEW_SCISSOR |
        _NEW_FRAG_CLAMP |
-       _NEW_TRANSFORM),      /* mesa state dependencies*/
+       _NEW_TRANSFORM |
+       _NEW_VIEWPORT),      /* mesa state dependencies*/
       (ST_NEW_VERTEX_PROGRAM |
        ST_NEW_RASTERIZER),  /* state tracker dependencies */
    },

src/mesa/state_tracker/st_extensions.c

@@ -463,6 +463,7 @@ void st_init_extensions(struct pipe_screen *screen,
       { o(ARB_derivative_control),           PIPE_CAP_TGSI_FS_FINE_DERIVATIVE          },
       { o(ARB_conditional_render_inverted),  PIPE_CAP_CONDITIONAL_RENDER_INVERTED      },
       { o(ARB_texture_view),                 PIPE_CAP_SAMPLER_VIEW_TARGET              },
+      { o(ARB_clip_control),                 PIPE_CAP_CLIP_HALFZ                       },
    };
 
    /* Required: render target and sampler support */