i965: Use last vertex convention for quad provoking vertex on sandybridge

Until we know how hw converts quads to polygon in beginning of
3D pipeline, for now unconditionally use last vertex convention.

Fix glean/clipFlat case.

diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
index 28549f2574ad2f1e064718fb172ee0ec7f1a8852..8fc322fd82edb9996ee0db66f282a4bbd19696b8 100644 (file)
--- a/src/mesa/drivers/dri/i965/brw_context.c
+++ b/src/mesa/drivers/dri/i965/brw_context.c
@@ -151,6 +151,13 @@ GLboolean brwCreateContext( int api,
       MIN2(ctx->Const.FragmentProgram.MaxNativeParameters,
           ctx->Const.FragmentProgram.MaxEnvParams);
 
+   /* Gen6 converts quads to polygon in beginning of 3D pipeline,
+      but we're not sure how it's actually done for vertex order,
+      that affect provoking vertex decision. Always use last vertex
+      convention for quad primitive which works as expected for now. */
+   if (intel->gen == 6)
+       ctx->Const.QuadsFollowProvokingVertexConvention = GL_FALSE;
+
    if (intel->is_g4x || intel->gen >= 5) {
       brw->CMD_VF_STATISTICS = CMD_VF_STATISTICS_GM45;
       brw->CMD_PIPELINE_SELECT = CMD_PIPELINE_SELECT_GM45;