Re: [Mesa3d-dev] RFC: allow resource_copy_region between different (yet compatabile) formats

[Luca B. <lu...@lu...>]

On Mon, Sep 6, 2010 at 3:57 PM, José Fonseca <jfo...@vm...> wrote:
> I'd like to know if there's any objection to change the
> resource_copy_region semantics to allow copies between different yet
> compatible formats, where the definition of compatible formats is:

I was about to propose something like this.

How about a much more powerful change though, that would make any pair
of non-blocked format of the same bit depth compatible?
This way you could copy z24s8 to r8g8b8a8, for instance.

In addition to this, how about explicitly allowing sampler views to
use a compatible format, and add the ability for surfaces to use a
compatible format too? (with a new parameter to get_tex_surface)

This would allow for instance to implement glBlitFramebuffer on
stencil buffers by reinterpreting the buffer as r8g8b8a8, and allow
the blitter module to copy depth/stencil buffers by simply treating
them as color buffers.

The only issue is that some drivers might hold depth/stencil surfaces
in compressed formats that cannot be interpreted as a color format,
and not have any mechanism for keeping temporaries or doing
conversions internally.

DirectX seems to have something like this with the _TYPELESS formats.