[Mesa-dev] [PATCH 1/3] mesa: Fold gallium's texture border stripping into a core Mesa option.

[Brian Paul]

On Mon, Oct 24, 2011 at 5:15 PM, Eric Anholt <eric at anholt.net> wrote:
> We wanted to reuse this in the Intel driver.
> ---
>  src/mesa/main/mtypes.h                 |   14 ++++++++
>  src/mesa/main/teximage.c               |   57 +++++++++++++++++++++++++++++--
>  src/mesa/state_tracker/st_cb_texture.c |   58 ++------------------------------
>  src/mesa/state_tracker/st_extensions.c |    2 +
>  4 files changed, 73 insertions(+), 58 deletions(-)
>
> diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
> index 719dff3..3309119 100644
> --- a/src/mesa/main/mtypes.h
> +++ b/src/mesa/main/mtypes.h
> @@ -1457,6 +1457,20 @@ struct gl_texture_attrib
>    /** GL_ARB_seamless_cubemap */
>    GLboolean CubeMapSeamless;
>
> +   /**
> +    * Whether the implementation strips out and ignores texture borders.
> +    *
> +    * Many GPU hardware implementations don't support rendering with texture
> +    * borders and mipmapped textures.  (Note: not static border color, but the
> +    * old 1-pixel border around each edge).  Implementations then have to do
> +    * slow fallbacks to be correct, or just ignore the border and be fast but
> +    * wrong.  Setting the flag stripts the border off of TexImage calls,
> +    * providing "fast but wrong" at significantly reduced driver complexity.
> +    *
> +    * Texture borders are deprecated in GL 3.0.
> +    **/
> +   GLboolean StripTextureBorder;

I think I'd like to see this put into the gl_constants state to make
it obvious that this is driver-specified constant state and not some
kind of settable texture state.


> +
>    /** Texture units/samplers used by vertex or fragment texturing */
>    GLbitfield _EnabledUnits;
>
> diff --git a/src/mesa/main/teximage.c b/src/mesa/main/teximage.c
> index 798201a..f1d1a7c 100644
> --- a/src/mesa/main/teximage.c
> +++ b/src/mesa/main/teximage.c
> @@ -2246,6 +2246,45 @@ _mesa_choose_texture_format(struct gl_context *ctx,
>    return f;
>  }
>
> +/**
> + * Adjust pixel unpack params and image dimensions to strip off the
> + * texture border.
> + *
> + * Gallium and intel don't support texture borders.  They've seldem been used
> + * and seldom been implemented correctly anyway.
> + *
> + * \param unpackNew returns the new pixel unpack parameters
> + */
> +static void
> +strip_texture_border(GLint *border,
> +                     GLint *width, GLint *height, GLint *depth,
> +                     const struct gl_pixelstore_attrib *unpack,
> +                     struct gl_pixelstore_attrib *unpackNew)
> +{
> +   assert(*border > 0);  /* sanity check */
> +
> +   *unpackNew = *unpack;
> +
> +   if (unpackNew->RowLength == 0)
> +      unpackNew->RowLength = *width;
> +
> +   if (depth && unpackNew->ImageHeight == 0)
> +      unpackNew->ImageHeight = *height;
> +
> +   unpackNew->SkipPixels += *border;
> +   if (height)
> +      unpackNew->SkipRows += *border;
> +   if (depth)
> +      unpackNew->SkipImages += *border;
> +
> +   assert(*width >= 3);
> +   *width = *width - 2 * *border;
> +   if (height && *height >= 3)
> +      *height = *height - 2 * *border;
> +   if (depth && *depth >= 3)
> +      *depth = *depth - 2 * *border;
> +   *border = 0;
> +}
>
>  /**
>  * Common code to implement all the glTexImage1D/2D/3D functions.
> @@ -2258,6 +2297,8 @@ teximage(struct gl_context *ctx, GLuint dims,
>          const GLvoid *pixels)
>  {
>    GLboolean error;
> +   struct gl_pixelstore_attrib unpack_no_border;
> +   const struct gl_pixelstore_attrib *unpack = &ctx->Unpack;
>
>    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);
>
> @@ -2322,6 +2363,16 @@ teximage(struct gl_context *ctx, GLuint dims,
>          return;   /* error was recorded */
>       }
>
> +      /* Allow a hardware driver to just strip out the border, to provide
> +       * reliable but slightly incorrect hardware rendering instead of
> +       * rarely-tested software fallback rendering.
> +       */
> +      if (border && ctx->Texture.StripTextureBorder) {
> +        strip_texture_border(&border, &width, &height, &depth, unpack,
> +                             &unpack_no_border);
> +        unpack = &unpack_no_border;
> +      }
> +

I think we also need this code in the glCopyTexImage() path.

-Brian