[Mesa-dev] [Bug 93813] Incorrect viewport range when GL_CLIP_ORIGIN is GL_UPPER_LEFT

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=93813

            Bug ID: 93813
           Summary: Incorrect viewport range when GL_CLIP_ORIGIN is
                    GL_UPPER_LEFT
           Product: Mesa
           Version: 10.6
          Hardware: x86-64 (AMD64)
                OS: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: Mesa core
          Assignee: mesa-dev at lists.freedesktop.org
          Reporter: jlegg at feralinteractive.com
        QA Contact: mesa-dev at lists.freedesktop.org

Created attachment 121191
  --> https://bugs.freedesktop.org/attachment.cgi?id=121191&action=edit
Test case

When GL_CLIP_ORIGIN is set to GL_UPPER_LEFT using glClipControl, the vertical
range of pixels that are written to during rendering does not match that which
was requested with glViewport unless the y offset is 0. It appears that during
rendering the y offset is always 0, and the height of the viewport is the
requested height minus the requested y offset (or 0 if that is negative).
However the GL_VIEWPORT values returned by glGet are what was originally
requested.

This was seen on both Intel Haswell on Ubuntu and AMD R9 270 on Fedora.

I have attached a test case. Examining the texture it produces with apitrace
shows it wrote to pixels 0 and 1 instead of pixels 1, 2, and 3 of a texture. It
should print "0, 1", but on affected machines it prints "1, 0". These values
are the contents of pixel 0 and 2. 0 is the cleared value before the draw, and
1 written in the draw (which uses a viewport of height 3 with y offset 1, so
only covers the second test pixel).

-- 
You are receiving this mail because:
You are the assignee for the bug.
You are the QA Contact for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freedesktop.org/archives/mesa-dev/attachments/20160121/c1ff8937/attachment.html>