[Mesa-dev] [PATCH v3 0/8] Implement support for EXT_blend_func_extended

[Ilia Mirkin]

On Thu, Nov 12, 2015 at 1:02 PM, Ryan Houdek <sonicadvance1 at gmail.com> wrote:
> In response to using FRAG_RESULT_DATA0 for both of the builtins that the
> extension provides for ES2.
> When looking at what _mesa_BindFragDataLocationIndexed does, it binds the
> output variable to DATA0+colorNumber that you passed in to it, and also sets
> that variable to being whatever index you passed in as well.
> Also looking at the rest of the source that references COLOR and DATA, it
> seems that in only ever expects one COLOR output, or as many DATA outputs as
> there can be.
> Also then that user defined outputs are bound to DATA rather than COLOR.
> So I think that using DATA for this is the proper way to go even though the
> builtin name wouldn't match. The alternative would be teaching the rest of
> mesa and the other drivers to expect multiple COLOR outputs with different
> indexes, all for the sake of matching an enum to a builtin variable name.

Actually it's all for the sake of support a purely hypothetical
multi-dual-source-blend situation. But the reality is that in that
case, things would break. I'd be perfectly happy throwing in an assert
saying that it's <= 1 and moving on.

  -ilia