[PATCH 5/5] wined3d: Alpha test emulation for core profile contexts.

[Henri Verbeet]

On 31 March 2016 at 19:51, Matteo Bruni <mbruni at codeweavers.com> wrote:
> +    shader_addline(buffer, "if (alpha_test)\n");
> +    if (alpha_func != WINED3D_CMP_NEVER)
> +        shader_addline(buffer, "    if (!(%s[0].a %s alpha_ref))\n",
> +                get_fragment_output(gl_info), comparison_operator[alpha_func - WINED3D_CMP_NEVER]);
> +    shader_addline(buffer, "        discard;\n");
Is there really an advantage to having the "alpha_test" uniform
instead of just mapping disabled alpha test to WINED3D_CMP_ALWAYS?

> @@ -973,6 +981,7 @@ struct ps_compile_args {
>      WORD texcoords_initialized; /* MAX_TEXTURES, 8 */
>      BOOL pointsprite;
>      BOOL flatshading;
> +    enum wined3d_cmp_func alpha_func;
>  };
>
>  enum fog_src_type {
> @@ -2022,6 +2031,7 @@ struct ffp_frag_settings
>      unsigned char pointsprite : 1;
>      unsigned char flatshading : 1;
>      unsigned char padding : 5;
> +    enum wined3d_cmp_func alpha_func;
"alpha_func" only needs 4 bits (3 if you just mask the 4th bit), so
would still fit in the padding. That applies somewhat to struct
ps_compile_args as well, although we may care less there.