Broken character models in dx8/9 games in wined3d

[Jesse Allen]

On 7/24/06, Jason Green <jave27 at gmail.com> wrote:
> I've spent a couple of days researching the issue of
> broken/upside-down character/object models in Wine in almost all newer
> games when you have vertex shaders enabled (Civ4, Half Life 2,
> Oblivion, Max Payne 2, etc.).

Yes, I remember some talk on IRC, and wanted to comment, but will do now.

>  I think I've boiled it down to a single
> case:  When "device->renderUpsideDown" is set in the case where vertex
> shaders are enabled.  That flag gets set in device.c:7395 when the
> current renderTarget is not on the current swapchain.  The comments in
> the source say that the upside-downedness is produced by
> glCopyTexImage, so it sets a flag to flip everything over.
>
> In the case w/o shaders, there is code in drawprim.c which loads the
> WORLDVIEW and PROJECTION matrices and then multiplies those matrices
> by one which inverts the y coordinates when that flag is set. That
> seems to work in the case without vertex shaders, but when shaders are
> enabled, they bypass the WORLD, VIEW, and PROJECTION matrices
> entirely.  The shader case was written when only software shaders
> worked, but that is no longer true.   It loads identity matrices and
> performs the y flip, but that code is entirely irrelevant since the
> vertex shader doesn't reference those matrices; it only uses constants
> that are passed by the app, which we can't perform any type of fixup
> on since we don't know which constants will be used for which
> calculation.

Yeah, I've noticed all this with Star Wars Battlefront. See bug 5247.

Without vertex shaders, I have a very simple hack to fix the one issue
of an upside down skybox. What I did should be quite obvious to you.
With vertex shaders (note: I make brief mention in bug comments about
how to get them working with dri, you might remember this from IRC
too) having them enabled, the problem gets a little worse as certain
parts of the skybox are correctly up and others upside down. If you
apply the hack, then *everything* got flipped -- those that were
correct were now upside down, and vice-versa. Also parts of the box
got shifted a bit. This is with ARB shaders BTW. I'll post screen
shots when I get the chance.  I wonder if there was a reason for the
flip code because it does flip some things correctly.


>
> So, I think what we need to do is prevent ourselves from having to do
> any flipping whatsoever. That's the part that I'm not sure how to do
> and is the reason for this email.

That I'd agree with. There are certainly things it does wrong. But I
think I need to go back studying the code before I make any
recommendations. :) I'll try to get back to you later.

Jesse