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 <[email protected]>
Reviewed-by: Roland Scheidegger <[email protected]>
Reviewed-by: Jose Fonseca <[email protected]>

1 files changed, 2 insertions, 0 deletions

diff --git a/src/gallium/drivers/softpipe/sp_state_derived.c b/src/gallium/drivers/softpipe/sp_state_derived.c
index 61153494c5b..9aa97d2d202 100644
--- a/src/gallium/drivers/softpipe/sp_state_derived.c
+++ b/src/gallium/drivers/softpipe/sp_state_derived.c
@@ -65,6 +65,8 @@ softpipe_get_vertex_info(struct softpipe_context *softpipe)
 {
    struct vertex_info *vinfo = &softpipe->vertex_info;
 
+   draw_prepare_shader_outputs(softpipe->draw);
+
    if (vinfo->num_attribs == 0) {
       /* compute vertex layout now */
       const struct tgsi_shader_info *fsInfo = &softpipe->fs_variant->info;