On Wed, Jan 11, 2017 at 2:00 PM, Alejandro Piñeiro <apinhe...@igalia.com> wrote:
> Before 4.5, GL_BACK was not allowed as a value of bufs. Since 4.5 it
> is allowed under some circunstances:
>
> From the OpenGL 4.5 specification, Section 17.4.1 "Selecting Buffers
> for Writing", page 493 (page 515 of the PDF):
> "An INVALID_ENUM error is generated if any value in bufs is FRONT ,
> LEFT , RIGHT , or FRONT_AND_BACK . This restriction applies to both
> the de- fault framebuffer and framebuffer objects, and exists
> because these constants may themselves refer to multiple buffers, as
> shown in table 17.4."
>
> And on page 492 (page 514 of the PDF):
> "If the default framebuffer is affected, then each of the constants
> must be one of the values listed in table 17.6 or the special value
> BACK . When BACK is used, n must be 1 and color values are written
> into the left buffer for single-buffered contexts, or into the back
> left buffer for double-buffered contexts."
>
> This patch keeps the same behaviour if OpenGL version is < 4. We
> assume that for 4.x this is the intended behaviour, so a fix, but for
> 3.x the intended behaviour is the already in place.
>
> Part of the fix for:
> GL45-CTS.direct_state_access.framebuffers_draw_read_buffers_errors
>
> v2: remove forgot printf
> ---
>
> Previous version has a debug printf that I forgot to remove. Sorry for
> the noise.
>
> src/mesa/main/buffers.c | 46 +++++++++++++++++++++++++++++++++-------------
> 1 file changed, 33 insertions(+), 13 deletions(-)
>
> diff --git a/src/mesa/main/buffers.c b/src/mesa/main/buffers.c
> index 2b24e5a..46ba4fd 100644
> --- a/src/mesa/main/buffers.c
> +++ b/src/mesa/main/buffers.c
> @@ -343,7 +343,9 @@ _mesa_NamedFramebufferDrawBuffer(GLuint framebuffer,
> GLenum buf)
> * \param n number of outputs
> * \param buffers array [n] of renderbuffer names. Unlike glDrawBuffer, the
> * names cannot specify more than one buffer. For example,
> - * GL_FRONT_AND_BACK is illegal.
> + * GL_FRONT_AND_BACK is illegal. The only exception is
> GL_BACK
> + * that is considered special and allowed as far as n is one
> + * since 4.5.
> */
> static void
> draw_buffers(struct gl_context *ctx, struct gl_framebuffer *fb,
> @@ -401,20 +403,38 @@ draw_buffers(struct gl_context *ctx, struct
> gl_framebuffer *fb,
> return;
> }
>
> - /* From the OpenGL 4.0 specification, page 256:
> - * "For both the default framebuffer and framebuffer objects, the
> - * constants FRONT, BACK, LEFT, RIGHT, and FRONT_AND_BACK are not
> - * valid in the bufs array passed to DrawBuffers, and will result in
> - * the error INVALID_ENUM. This restriction is because these
> - * constants may themselves refer to multiple buffers, as shown in
> - * table 4.4."
> - * Previous versions of the OpenGL specification say
> INVALID_OPERATION,
> - * but the Khronos conformance tests expect INVALID_ENUM.
> + /* From the OpenGL 4.5 specification, page 493 (page 515 of the PDF)
> + * "An INVALID_ENUM error is generated if any value in bufs is FRONT
> + * , LEFT , RIGHT , or FRONT_AND_BACK . This restriction applies to
Need no space before comma. Move it after the comma.
> + * both the de- fault framebuffer and framebuffer objects, and
> + * exists because these constants may themselves refer to multiple
> + * buffers, as shown in table 17.4."
> + *
> + * And on page 492 (page 514 of the PDF):
> + * "If the default framebuffer is affected, then each of the
> + * constants must be one of the values listed in table 17.6 or the
> + * special value BACK . When BACK is used, n must be 1 and color
> + * values are written into the left buffer for single-buffered
> + * contexts, or into the back left buffer for double-buffered
> + * contexts."
> + *
> + * Note "special value BACK". GL_BACK also refers to multiple buffers,
> + * but it is consider a special case here. This is a change on 4.5. For
> + * OpenGL 4.x we check that behaviour. For any previous version we keep
> + * considering it wrong (as INVALID_ENUM).
> */
> if (_mesa_bitcount(destMask[output]) > 1) {
> - _mesa_error(ctx, GL_INVALID_ENUM, "%s(invalid buffer %s)",
> - caller, _mesa_enum_to_string(buffers[output]));
> - return;
> + if (_mesa_is_winsys_fbo(fb) && ctx->Version >= 40 &&
> buffers[output] == GL_BACK) {
Split in two lines. Exceeding the 80 character limit.
> + if (n != 1) {
> + _mesa_error(ctx, GL_INVALID_OPERATION, "%s(with GL_BACK n
> must be 1)",
> + caller);
> + return;
> + }
> + } else {
> + _mesa_error(ctx, GL_INVALID_ENUM, "%s(invalid buffer %s)",
> + caller, _mesa_enum_to_string(buffers[output]));
> + return;
> + }
> }
>
> /* Section 4.2 (Whole Framebuffer Operations) of the OpenGL ES 3.0
> --
> 2.9.3
>
> _______________________________________________
> mesa-dev mailing list
> mesa-dev@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/mesa-dev
With above comments fixed, both patches are:
Reviewed-by: Anuj Phogat <anuj.pho...@gmail.com>
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