Implement early depth test.

Early depth test is enabled when depth test is enabled and
alpha test is disabled and fragment shader does not write
depth.
The early-z is implemented by moving the depth test stage
just before the fragment shader stage and prepending it
with an earlyz stage, introduced with this commit.
The earlyz stage prepares the quad->outputs.depth for
the following depth test stage by interpolating Z position,
just as the fragment shader would do.

1 files changed, 1 insertions, 0 deletions

diff --git a/src/mesa/pipe/softpipe/sp_context.h b/src/mesa/pipe/softpipe/sp_context.h
index a411969bc0..872766101d 100644
--- a/src/mesa/pipe/softpipe/sp_context.h
+++ b/src/mesa/pipe/softpipe/sp_context.h
@@ -134,6 +134,7 @@ struct softpipe_context {
    /** Software quad rendering pipeline */
    struct {
       struct quad_stage *polygon_stipple;
+      struct quad_stage *earlyz;
       struct quad_stage *shade;
       struct quad_stage *alpha_test;
       struct quad_stage *stencil_test;