Per ARB_vertex_program spec result registers are 4-component and initially
undefined, and the FF fragment program expects its intputs to be
4-component too. So, if the client's vertex program does not write the
whole vector it will cause misrenderings unless the same client also
supplies fragment program that expects less than 4 componens.
This commit adds a workaround that initializes results to vec4(0, 0, 0, 1)
which seems to be an expected behavior for such clients.
Cc: mesa-stable
Signed-off-by: Sviatoslav Peleshko <sviatoslav.peleshko@globallogic.com>
Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/38295>
Sviatoslav Peleshko
f03432c81a