[Mesa-dev] [PATCH] mesa: Skip mipmap generation if there is no source image.

[Brian Paul]

On 10/17/2011 02:45 PM, Eric Anholt wrote:
> The spec doesn't explicitly mandate this behavior, but it seems like
> the only sensible thing to do (as opposed to assertion failing or
> segfaulting).
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=40308
> ---
>
> Oops, looks like I never sent this one out for review.
>
>   src/mesa/main/mipmap.c |    4 +++-
>   1 files changed, 3 insertions(+), 1 deletions(-)
>
> diff --git a/src/mesa/main/mipmap.c b/src/mesa/main/mipmap.c
> index c2f9226..2b6aead 100644
> --- a/src/mesa/main/mipmap.c
> +++ b/src/mesa/main/mipmap.c
> @@ -2036,7 +2036,9 @@ _mesa_generate_mipmap(struct gl_context *ctx, GLenum target,
>
>      ASSERT(texObj);
>      srcImage = _mesa_select_tex_image(ctx, texObj, target, texObj->BaseLevel);
> -   ASSERT(srcImage);
> +
> +   if (!srcImage)
> +      return;
>
>      maxLevel = _mesa_max_texture_levels(ctx, texObj->Target) - 1;
>      ASSERT(maxLevel>= 0);  /* bad target */

I think this check should come sooner.  We typically do error checking 
and no-op checking before calling the ctx->Driver.Foobar() functions.

The above fix might work for the fallback path, but what about if 
ctx->Driver.GenerateMipmap points to _mesa_meta_GenerateMipmap() or 
st_generate_mipmap()?

I think I'd try to do the check in _mesa_GenerateMipmapEXT().

-Brian