[Mesa-dev] [PATCH] mesa: check bits per channel for GL_RGBA_SIGNED_COMPONENTS_EXT query

[Matt Turner]

On Wed, Jan 8, 2014 at 4:37 PM, Brian Paul <brianp at vmware.com> wrote:
> If a channel has zero bits it's not signed.
>
> v2: also check for luminance and intensity format bits.  Bruce
> Merry's proposed piglit test hits the luminance case.
>
> Bugzilla: http://bugs.freedesktop.org/show_bug.cgi?id=73096
> Cc: 10.0 <mesa-stable at lists.freedesktop.org>
> ---
>  src/mesa/main/get.c |   37 ++++++++++++++++++++++++++++++-------
>  1 file changed, 30 insertions(+), 7 deletions(-)
>
> diff --git a/src/mesa/main/get.c b/src/mesa/main/get.c
> index c45a8d1..c73b935 100644
> --- a/src/mesa/main/get.c
> +++ b/src/mesa/main/get.c
> @@ -769,13 +769,36 @@ find_custom_value(struct gl_context *ctx, const struct value_desc *d, union valu
>           /* Note: we only check the 0th color attachment. */
>           const struct gl_renderbuffer *rb =
>              ctx->DrawBuffer->_ColorDrawBuffers[0];
> -         const GLboolean is_signed =
> -            rb ? _mesa_is_format_signed(rb->Format) : GL_FALSE;
> -         /* At this time, all color channels have same signedness */
> -         v->value_int_4[0] =
> -         v->value_int_4[1] =
> -         v->value_int_4[2] =
> -         v->value_int_4[3] = is_signed;
> +         if (rb && _mesa_is_format_signed(rb->Format)) {
> +            /* Issue 17 of GL_EXT_packed_float:  If a component (such as
> +             * alpha) has zero bits, the component should not be considered
> +             * signed and so the bit for the respective component should be
> +             * zeroed.
> +             */
> +            GLint r_bits =
> +               _mesa_get_format_bits(rb->Format, GL_RED_BITS);
> +            GLint g_bits =
> +               _mesa_get_format_bits(rb->Format, GL_GREEN_BITS);
> +            GLint b_bits =
> +               _mesa_get_format_bits(rb->Format, GL_BLUE_BITS);
> +            GLint a_bits =
> +               _mesa_get_format_bits(rb->Format, GL_ALPHA_BITS);
> +            GLint l_bits =
> +               _mesa_get_format_bits(rb->Format, GL_TEXTURE_LUMINANCE_SIZE);
> +            GLint i_bits =
> +               _mesa_get_format_bits(rb->Format, GL_TEXTURE_INTENSITY_SIZE);
> +
> +            v->value_int_4[0] = r_bits + l_bits + i_bits > 0;
> +            v->value_int_4[1] = g_bits + l_bits + i_bits > 0;
> +            v->value_int_4[2] = b_bits + l_bits + i_bits > 0;
> +            v->value_int_4[3] = a_bits + i_bits > 0;
> +         }
> +         else {
> +            v->value_int_4[0] =
> +            v->value_int_4[1] =
> +            v->value_int_4[2] =
> +            v->value_int_4[3] = 0;
> +         }
>        }
>        break;
>
> --
> 1.7.10.4

Reviewed-by: Matt Turner <mattst88 at gmail.com>