draw: inject frontface info into wireframe outputs

Draw module can decompose primitives into wireframe models, which
is a fancy word for 'lines', unfortunately that decomposition means
that we weren't able to preserve the original front-face info which
could be derived from the original primitives (lines don't have a
'face'). To fix it allow draw module to inject a fake face semantic
into outputs from which the backends can figure out the original
frontfacing info of the primitives.

Signed-off-by: Zack Rusin <zackr@vmware.com>
Reviewed-by: Roland Scheidegger <sroland@vmware.com>
Reviewed-by: Jose Fonseca <jfonseca@vmware.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/gallium/drivers/svga/svga_swtnl_state.c b/src/gallium/drivers/svga/svga_swtnl_state.c
index d744f18..d60af3f 100644
--- a/src/gallium/drivers/svga/svga_swtnl_state.c
+++ b/src/gallium/drivers/svga/svga_swtnl_state.c
@@ -162,6 +162,7 @@ svga_swtnl_update_vdecl( struct svga_context *svga )
    memset(vinfo, 0, sizeof(*vinfo));
    memset(vdecl, 0, sizeof(vdecl));
 
+   draw_prepare_shader_outputs(draw);
    /* always add position */
    src = draw_find_shader_output(draw, TGSI_SEMANTIC_POSITION, 0);
    draw_emit_vertex_attr(vinfo, EMIT_4F, INTERP_LINEAR, src);