[Mesa-dev] [PATCH 3/3] util/u_blit: Implement util_blit_pixels via pipe_context::blit.

[Marek Olšák]

On Wed, Sep 18, 2013 at 12:36 PM, Jose Fonseca <jfonseca at vmware.com> wrote:
> ----- Original Message -----
>> Isn't u_blit a candidate for removal considering it has no user in Mesa?
>
> u_blit still has users outside mesa. And it provides features that pipe_context::blit does not:
>
> - util_blit_pixels() will call pipe_context::resource_copy for non-stretch blits, which is potentially faster than pipe_context::blit

The decision whether resource_copy_region should be used has been
moved to drivers since pipe->blit was added. All that drivers need to
do is to call util_try_blit_via_copy_region.

> - util_blit_pixels_tex() allows to specify pipe_sampler_view::swizzle_?
>
> Ie., the ability to do textured quad blits from state tracker is something that will be often handy.
>
> The reasons I need custom pipe_sampler_view::swizzle_? is to simulate DX9 formats (which have ?, 1, 1, 1 swizlle; while gallium/OpenGL/D3D10 formats has ?, 0, 0, 1 swizzle).  The only way to use pipe_context::blit would be to
> a) extend pipe_context::blit to receive pipe_sampler_view::swizzle_?
> b) add ?, 1, 1, 1 variants for all DX9 formats...
>
> Both seemed more work than what was worth.

Actually I think adding ?,1,1,1 variants would be really easy. You can
name the formats e.g. PIPE_FORMAT_R8_UNORM_DX9, etc. I think you only
need to add one line to u_format_csv, one line to p_format.h, and
support for your driver. Then you would be able to use pipe->blit and
you don't have to rely on pipe_sampler_view::swizzle_?.

Marek