st/mesa: initialize lower alpha func to ALWAYS
The lower_alpha_func is initialized as COMPARE_FUNC_NEVER, and the
nir_lower_alpha_test() only executed if the alpha_func has changed.
This means when user runs an alpha test with GL_NEVER function the
lowering is never executed, and no fragment is discarded.
Rather, we would like to initialize the function as COMPARE_FUNC_ALWAYS,
and run the lowering when the alpha_func is different. If user runs the
alpha test with GL_ALWAYS, indeed the lowering is never executed; but
using GL_ALWAYS makes no fragment is discarded, so it is like not
executing the testing.
Signed-off-by: Juan A. Suarez Romero <jasuarez@igalia.com>
Reviewed-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7251>
4 files changed
