Re: wined3d: Mark vertex shader 3.0 as foggy shaders if they write out the fog coord

[Ivan Gyurdiev]

Fabian Bieler wrote:
> Vertex shaders are marked as 'foggy shaders' in wined3d if they write out the 
> fog coord. Previously this was not done for vertex shaders 3.0. This patch 
> corrects this problem.

Please don't do that - the design is flawed enough as it is (GLSL being 
invoked from vertexshader and such..).

The reg_maps was meant to be:
- computed in shader pass 1 [ register tracking ]
- used in shader pass 2 [ code generation ].

Here you're doing this:
- computing reg_maps at the very end of shader pass 2 [ unpack stage ]
- using this right afterwards in the calling function to set yet another 
flag (This->usesFog).

I'm not sure what needs to be done instead, since it all looks so broken...

- I would say this type of analysis about shader usage needs to go into 
pass 1 (baseshader), since it is backend independent. It's kind of 
vertex-shader specific, but we're trying to merge vertex and pixel 
shaders, and remove code from these two files, not add more of it.

- The usesFog looks like it's trying to persist information about 
register usage after the shader has been compiled for optimization 
purposes...except that this information is already persisted - if you 
look in baseshader, you will see the entire reg_maps structure is kept 
in there, exactly for that purpose [ was done for software shaders 
actually, but that never happened ].

- Also, other code outside the shaders should not be accessing these 
flags directly - there should be a function which looks inside the 
reg_maps, and code from other file should call that function (we are 
emulating OOP programming in C, so we should try to use encapsulation).

Ivan

wined3d: Mark vertex shader 3.0 as foggy shaders if they write out the fog coord

[Ivan Gyurdiev]

Here is how this was meant to work at some point [ since I see all kinds 
of incorrect things being done ]:

   Entry point                                 Code generation
   ==============================

   Pixelshader -------- Baseshader ------- ARB backend
   Vertexshader -------                  ------- GLSL backend

   Code should be moving towards the center from both directions.
   Vertex and pixelshader: Should contain minimum amount of things
   Baseshader: Should contain anything backend [ and frontend ] 
independent. I think it's acceptable to put some things that are 
frontend-dependent in baseshader, as long as they can be written in a 
generic way, without tons of (if (pshader) do_x else if (vshader) do_y 
statements).

   Pass 0: Tracing: 100% done in baseshader.

   Pass 1: Register tracking: 100% done in baseshader.

   Pass 2: Backend independent gen code: In baseshader
      [ this includes the opcode loop, and all "parsing" of the shader asm ]

   Pass 2: Backend dependent gen code: In ARB or GLSL files
      [ ideally should work with pre-processed shader asm, and broken 
out tokens
        - a sort of an intermediate representation if you prefer ]

wined3d: Mark vertex shader 3.0 as foggy shaders if they write out the fog coord

[H. Verbeet]

On 12/04/07, Ivan Gyurdiev <ivg231(a)gmail.com> wrote:
> I'm not sure what needs to be done instead, since it all looks so broken...
>
> - I would say this type of analysis about shader usage needs to go into
> pass 1 (baseshader), since it is backend independent. It's kind of
> vertex-shader specific, but we're trying to merge vertex and pixel
> shaders, and remove code from these two files, not add more of it.

It should probably go into shader_get_registers_used() in
baseshader.c, where we fill semantics_out, around line 255.