[Bug 109371] New: Textures seem to be byteswapped on big endian architectures - bugzilla-daemon-CC+yJ3UmIYqDUpFQwHEjaQ

From: bugzilla-daemon-CC+yJ3UmIYqDUpFQwHEjaQ@public.gmane.org
To: nouveau-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org
Subject: [Bug 109371] New: Textures seem to be byteswapped on big endian architectures
Date: Wed, 16 Jan 2019 00:36:08 +0000	[thread overview]
Message-ID: <bug-109371-8800@http.bugs.freedesktop.org/> (raw)

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https://bugs.freedesktop.org/show_bug.cgi?id=109371

            Bug ID: 109371
           Summary: Textures seem to be byteswapped on big endian
                    architectures
           Product: Mesa
           Version: 18.3
          Hardware: PowerPC
                OS: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: Drivers/DRI/nouveau
          Assignee: nouveau-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org
          Reporter: kungfujesus06-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
        QA Contact: nouveau-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org

When using an NV43 based GPU on a PPC64 kernel with a 64 bit userspace, it
seems applications will have byte swapped textures when specified with GL_RGBA
and GL_UNSIGNED_BYTE.  Matplotlib will do this when blit=True for the plot
routines, and several games will have this issue.  In particular, for Legacy
Doom, I've found that if I swap the textures so that they are A,B,G,R just
before the textures are mapped, everything is correct.  

I also found that doing glPixelStorei(GL_UNPACK_BYTES, GL_TRUE) and choosing
GL_UNSIGNED_INT_8_8_8_8 as the representation seemed to also remedy this.  I
found that the _REV variant didn't byte swap the textures back to the incorrect
ordering (this is probably a different bug).

Easiest way to demonstrate the bug:
svn co https://svn.code.sf.net/p/doomlegacy/svn/legacy_one/trunk doomlegacy
cd doomlegacy
make OS=LINUX
make
cd bin
Grab this archive:
https://sourceforge.net/projects/doomlegacy/files/1.47.2/doomlegacy_1.47.2_common.zip/download,
unzip it, extract legacy.wad into the bin directory
Grab this archive:
https://github.com/freedoom/freedoom/releases/download/v0.11.3/freedoom-0.11.3.zip,
extract, move freedoom1.wad into the bin directory.
Then do:
./doomlegacy -iwad freedoom1.wad -opengl

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