Details
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Bug
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Resolution: Unresolved
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P2: Important
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None
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6.6.2
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None
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GNOME 45
Wayland
Gentoo Linux
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Linux/Wayland
Description
Qt 6.6.2 is causing a GL error when QOpenGLWidget is used, complicating application debugging.
Python example program (also seen with C++), glerror:
import sys from PyQt6.QtOpenGLWidgets import * from PyQt6.QtWidgets import * class Dialog(QDialog): def __init__(self, parent=None): super().__init__(parent) self.setGeometry(0, 0, 100, 100) glwidget = QOpenGLWidget() layout = QVBoxLayout() layout.addWidget(glwidget) self.setLayout(layout) app = QApplication(sys.argv) dialog = Dialog() dialog.show() app.exec()
$ MESA_DEBUG=1 ./glerror Mesa: error: GL_INVALID_OPERATION in glDrawBuffers(unsupported buffer GL_BACK_LEFT)
This is independent of Mesa driver, with the software driver:
$ LIBGL_ALWAYS_SOFTWARE=1 QSG_INFO=1 MESA_DEBUG=1 ./glerror qt.rhi.general: Created OpenGL context QSurfaceFormat(version 4.5, options QFlags<QSurfaceFormat::FormatOption>(DeprecatedFunctions), depthBufferSize 0, redBufferSize 8, greenBufferSize 8, blueBufferSize 8, alphaBufferSize 8, stencilBufferSize 0, samples 0, swapBehavior QSurfaceFormat::DefaultSwapBehavior, swapInterval 1, colorSpace QColorSpace(), profile QSurfaceFormat::CompatibilityProfile) qt.rhi.general: OpenGL VENDOR: Mesa RENDERER: llvmpipe (LLVM 17.0.6, 256 bits) VERSION: 4.5 (Compatibility Profile) Mesa 24.0.1 Mesa: error: GL_INVALID_OPERATION in glDrawBuffers(unsupported buffer GL_BACK_LEFT)
The only place in QtBase I can find GL_BACK_LEFT is:
https://code.qt.io/cgit/qt/qtbase.git/tree/src/gui/rhi/qrhigles2.cpp?h=6.6.2#n3168