Bug 96617

Summary:	gl_SecondaryFragDataEXT doesn't work for extended blend func
Product:	Mesa	Reporter:	Corentin Wallez <corentin>
Component:	Mesa core	Assignee:	mesa-dev
Status:	RESOLVED FIXED	QA Contact:	mesa-dev
Severity:	normal
Priority:	medium
Version:	11.2
Hardware:	x86-64 (AMD64)
OS:	Linux (All)
Whiteboard:
i915 platform:		i915 features:

Description Corentin Wallez 2016-06-21 17:50:32 UTC

Using GL_EXT_blend_func_extended works with gl_FragColor / gl_SecondaryFragColorEXT but not with gl_FragData[0] / gl_SecondaryFragDataEXT[0]

This was found when trying to use the 3.3 core profile in Chromium.

See https://github.com/Kangz/GLDriverBugs/blob/master/gl_secondary_frag_data/Main.cpp#L24 for a repro case (no blue triangle shows up).

Comment 1 Ilia Mirkin 2016-06-21 19:02:29 UTC

https://patchwork.freedesktop.org/patch/94448/

This fixes a hacked up piglit test for me, but need to do more testing before pushing.

Comment 2 Corentin Wallez 2016-06-21 19:19:46 UTC

Thanks for taking a look at this so quickly!

Comment 3 Ilia Mirkin 2016-06-22 02:02:39 UTC

I pushed a slightly improved version of the patch:

commit 36ed1b695e5a0ae5714b79cae3a089b5e7e8bd29
Author: Ilia Mirkin <imirkin@alum.mit.edu>
Date:   Tue Jun 21 16:16:17 2016 -0400

    glsl: only match gl_FragData and not gl_SecondaryFragDataEXT

    There's special logic around finding gl_FragData. It latches onto any
    array with FRAG_RESULT_DATA0. However gl_SecondaryFragDataEXT[], added
    by GL_EXT_blend_func_extended, fits those parameters as well. The real
    frag data array should have index 0 though, so we can use that to
    distinguish them.
    
    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=96617
    Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
    Cc: "11.1 11.2 12.0" <mesa-stable@lists.freedesktop.org>
    Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

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