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  1. Qt
  2. QTBUG-37427

tst_QGL::clipTest() fails because QNX graphics drivers don't preserve bits in the back buffer

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: P3: Somewhat important
    • Resolution: Done
    • Affects Version/s: 5.2.0, 5.3.0 Beta1, 5.4.0
    • Fix Version/s: 5.3.0 RC1
    • Labels:
      None
    • Environment:
      x86 QNX SDP 6.6.0

      Z30 with 127.0.2.1091

      BlackBerry 10 Device Simulator (Developer) trunk.1073
    • Platform/s:
      QNX

      Description

      tst_QGL produces many clipTest failures because the QNX graphics drivers don't preserve bits when a buffer swap occurs (EGL_SWAP_BEHAVIOR).

      1) Create a developer build of Qt with tests.
      2) From the qtbase/tests/auto/opengl/qgl directory, run "./tst_qgl clipTest".

      Many test failures that look like the following will occur:
      FAIL! : tst_QGL::clipTest() Pixel Max fuzz (1) exceeded: (0,0,0,255) vs (255,255,255,255)
      Loc: [tst_qgl.cpp(1795)]

      I think it's because the back buffer is uninitialized. The back buffer doesn't start from a copy of what's in the front buffer. The application draws once, swaps buffers and then compares. What it's comparing to is...empty.

      Not sure whether this a problem with the test, QNX failing to live up to a Qt expectation or Qt failing to deal with the lack of preservation.

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            Assignee:
            bomb3rman Fabian Bumberger
            Reporter:
            jmcdonnell James McDonnell
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              Dates

              Created:
              Updated:
              Resolved:

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