gallium: add PIPE_CAP_QUADS_FOLLOW_PROVOKING_VERTEX_CONVENTION

Just let the hardware do it if it can and avoid drivers having to
check for the special case on each draw call.

v2: update the draw module

6 files changed, 29 insertions, 10 deletions

diff --git a/src/gallium/auxiliary/draw/draw_context.c b/src/gallium/auxiliary/draw/draw_context.c
index 3c0b1aa39c9..ad49ce733ac 100644
--- a/src/gallium/auxiliary/draw/draw_context.c
+++ b/src/gallium/auxiliary/draw/draw_context.c
@@ -93,11 +93,11 @@ draw_create_context(struct pipe_context *pipe, boolean try_llvm,
    }
 #endif
 
+   draw->pipe = pipe;
+
    if (!draw_init(draw))
       goto err_destroy;
 
-   draw->pipe = pipe;
-
    return draw;
 
 err_destroy:
@@ -168,6 +168,9 @@ boolean draw_init(struct draw_context *draw)
    if (!draw_gs_init( draw ))
       return FALSE;
 
+   draw->quads_always_flatshade_last = !draw->pipe->screen->get_param(
+      draw->pipe->screen, PIPE_CAP_QUADS_FOLLOW_PROVOKING_VERTEX_CONVENTION);
+
    return TRUE;
 }
 
diff --git a/src/gallium/auxiliary/draw/draw_decompose_tmp.h b/src/gallium/auxiliary/draw/draw_decompose_tmp.h
index a142563af97..ee6877df99d 100644
--- a/src/gallium/auxiliary/draw/draw_decompose_tmp.h
+++ b/src/gallium/auxiliary/draw/draw_decompose_tmp.h
@@ -193,13 +193,18 @@ FUNC(FUNC_VARS)
             flags = DRAW_PIPE_RESET_STIPPLE |
                     DRAW_PIPE_EDGE_FLAG_0 |
                     DRAW_PIPE_EDGE_FLAG_1;
-            /* XXX should always emit idx[0] first */
-            /* always emit idx[3] first */
-            TRIANGLE(flags, idx[3], idx[0], idx[1]);
+            /* always emit idx[3] / idx[0] first */
+            if (quads_flatshade_last)
+               TRIANGLE(flags, idx[3], idx[0], idx[1]);
+            else
+               TRIANGLE(flags, idx[0], idx[1], idx[2]);
 
             flags = DRAW_PIPE_EDGE_FLAG_1 |
                     DRAW_PIPE_EDGE_FLAG_2;
-            TRIANGLE(flags, idx[3], idx[1], idx[2]);
+            if (quads_flatshade_last)
+               TRIANGLE(flags, idx[3], idx[1], idx[2]);
+            else
+               TRIANGLE(flags, idx[0], idx[2], idx[3]);
          }
       }
       break;
@@ -237,13 +242,18 @@ FUNC(FUNC_VARS)
                flags = DRAW_PIPE_RESET_STIPPLE |
                        DRAW_PIPE_EDGE_FLAG_0 |
                        DRAW_PIPE_EDGE_FLAG_1;
-               /* XXX should always emit idx[0] first */
-               /* always emit idx[3] first */
-               TRIANGLE(flags, idx[3], idx[2], idx[0]);
+               /* always emit idx[3] / idx[0 first */
+               if (quads_flatshade_last)
+                  TRIANGLE(flags, idx[3], idx[2], idx[0]);
+               else
+                  TRIANGLE(flags, idx[0], idx[3], idx[2]);
 
                flags = DRAW_PIPE_EDGE_FLAG_1 |
                        DRAW_PIPE_EDGE_FLAG_2;
-               TRIANGLE(flags, idx[3], idx[0], idx[1]);
+               if (quads_flatshade_last)
+                  TRIANGLE(flags, idx[3], idx[0], idx[1]);
+               else
+                  TRIANGLE(flags, idx[0], idx[1], idx[3]);
             }
          }
       }
diff --git a/src/gallium/auxiliary/draw/draw_gs_tmp.h b/src/gallium/auxiliary/draw/draw_gs_tmp.h
index de7b02655a5..92b6fb75ea1 100644
--- a/src/gallium/auxiliary/draw/draw_gs_tmp.h
+++ b/src/gallium/auxiliary/draw/draw_gs_tmp.h
@@ -9,6 +9,7 @@
    const unsigned prim = input_prims->prim;                       \
    const unsigned prim_flags = input_prims->flags;                \
    const unsigned count = input_prims->count;                     \
+   const boolean quads_flatshade_last = FALSE;                    \
    const boolean last_vertex_last = TRUE;                         \
    do {                                                           \
       debug_assert(input_prims->primitive_count == 1);            \
diff --git a/src/gallium/auxiliary/draw/draw_private.h b/src/gallium/auxiliary/draw/draw_private.h
index c3eca973e92..9e6380341da 100644
--- a/src/gallium/auxiliary/draw/draw_private.h
+++ b/src/gallium/auxiliary/draw/draw_private.h
@@ -204,6 +204,8 @@ struct draw_context
       boolean guard_band_xy;
    } driver;
 
+   boolean quads_always_flatshade_last;
+
    boolean flushing;         /**< debugging/sanity */
    boolean suspend_flushing; /**< internally set */
 
diff --git a/src/gallium/auxiliary/draw/draw_pt_decompose.h b/src/gallium/auxiliary/draw/draw_pt_decompose.h
index 3127aad7310..8637085064a 100644
--- a/src/gallium/auxiliary/draw/draw_pt_decompose.h
+++ b/src/gallium/auxiliary/draw/draw_pt_decompose.h
@@ -1,5 +1,7 @@
 #define LOCAL_VARS                           \
    char *verts = (char *) vertices;          \
+   const boolean quads_flatshade_last =      \
+      draw->quads_always_flatshade_last;     \
    const boolean last_vertex_last =          \
       !(draw->rasterizer->flatshade &&       \
         draw->rasterizer->flatshade_first);
diff --git a/src/gallium/auxiliary/draw/draw_so_emit_tmp.h b/src/gallium/auxiliary/draw/draw_so_emit_tmp.h
index 7fafde9d5e6..ec31c3ff32f 100644
--- a/src/gallium/auxiliary/draw/draw_so_emit_tmp.h
+++ b/src/gallium/auxiliary/draw/draw_so_emit_tmp.h
@@ -9,6 +9,7 @@
    /* declare more local vars */                                  \
    const unsigned prim = input_prims->prim;                       \
    const unsigned prim_flags = input_prims->flags;                \
+   const boolean quads_flatshade_last = FALSE;                    \
    const boolean last_vertex_last = TRUE;                         \
    do {                                                           \
       debug_assert(input_prims->primitive_count == 1);            \