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  1. Qt
  2. QTBUG-84091

Qml font rendering bug due to glCullFace(GL_FRONT)

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    Details

    • Type: Bug
    • Status: Reported
    • Priority: P2: Important
    • Resolution: Unresolved
    • Affects Version/s: 5.12.8
    • Fix Version/s: None
    • Labels:
      None
    • Environment:
      Ubuntu 20.04
    • Platform/s:
      Linux/X11

      Description

      We are using Qml to build an OpenGL program. We share the same opengl context with Qt.

      During our rendering, we set glCullFace(GL_FRONT), and call QQuickWindow::resetOpenGLState() after our rendering.

      Then occasionally, Qt renders the fonts incorrectly.

      Currently we get around this problem by calling glCullFace(GL_BACK) after our rendering.

      Since the fonts are rendered correctly sometimes, we think there exists a call to glCullFace(GL_BACK) somewhere in the Qt rendering code path. But that is not guaranteed to be run. So we suggest to add glCullFace(GL_BACK) to QQuickWindow::resetOpenGLState() to ensure that Qt renders fonts correctly.

      And another API might also need to be reset: glClipControl()

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            Assignee:
            esabraha Eskil Abrahamsen Blomfeldt
            Reporter:
            xuzhongxing Zhongxing Xu
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              Dates

              Created:
              Updated:

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