[PATCH 3/5] wined3d: Make the condition to enter p8 conversion shader path more strict.

[Alexander Dorofeyev]

Henri Verbeet wrote:
> 2008/8/31 Alexander Dorofeyev <alexd4 at inbox.lv>:
>> This prevents shader path from being entered for an offscreen surface when
>> there is p8 render target and fixes failures in ddraw visual test (with
>> opengl rendering and RTL_READDRAW mode) and visual glitches in Red Alert.
>> ---
>>  dlls/wined3d/surface.c |    6 +++++-
>>  1 files changed, 5 insertions(+), 1 deletions(-)
>>
> This is probably ok for this specific case, but in general I think
> primary_render_target_is_p8() is somewhat broken. It seems that in
> most places where it's used it is assumed that "This" is the primary
> render target. In some cases that's actually always true, but in those
> cases primary_render_target_is_p8() wouldn't need to check if there's
> a primary render target, it could just use a surface passed in as
> parameter. In the other cases, you don't actually know the surface is
> the primary render target, and you'd need to verify that first, after
> which you've essentially got the first case again.

I think that it's not that primary_render_target_is_p8() is broken, but things 
sometimes get confusing because there are two kinds of cases. Sometimes, we only 
want to care that primary is p8 (this is used as kind of indicator we are in 8 
bit 2-D ddraw game and don't need to care about 3D requirements) and if so do 
something for all p8 surfaces. d3dfmt_p8_init_palette is one such place (index 
in alpha optimization).

But one case with different requirements seems to be the p8 conversion shader. I 
think as it is currently implemented, it is only meant to work for the p8 
primary itself. But, because primary_render_target_is_p8() check was used in 
d3dfmt_get_conv, p8 conversion shader-specific paths were sometimes hit when 
they shouldn't.