Viewport rendering misaligned on HiDPI display (RTX 5070, Ubuntu 22.04/24.04 Xorg) #6939
Description
Describe the Bug
The 3D viewport in Webots R2025a is misaligned and renders only in the bottom-left corner of the window. The remaining area of the 3D view remains black and does not refresh. This issue persists on a high-DPI display (2560x1600) even when system scaling is set to 100%.
Steps to Reproduce
Launch Webots R2025a (installed via .deb package) on Ubuntu.
Open any world file, such as pr2.wbt.
Observe the 3D rendering area.
The 3D scene is confined to the bottom-left quadrant of the viewport.
Expected behavior
The 3D scene should be correctly mapped to the entire viewport area within the application window.
System
Operating System: Linux Ubuntu (Xorg session confirmed with Wayland disabled).
Graphics Card: NVIDIA GeForce RTX 5070 Laptop GPU.
Driver Version: 590.48.01.
Webots Version: R2025a.
Additional context
The "Display scaling" option is missing from the Preferences -> General tab, preventing manual scale overrides.
Attempted environment variables such as QT_AUTO_SCREEN_SCALE_FACTOR=0 and QT_SCALE_FACTOR=1 did not resolve the issue.
Manually editing ~/.config/Cyberbotics/Webots-R2025a.conf to set desktopScale=1 had no effect.
nvidia-smi confirms the NVIDIA driver is active and managing the Xorg process.
The issue seems related to how the OpenGL viewport is calculated on RTX 50-series hardware with HiDPI screens under X11.