KWin supports a number of environment variables to overwrite some settings or checks. The following variables are supported:
The environment variable KWIN_COMPOSE enforces a compositing backend or forces compositing completely off. The following values are supported:
By default KWin uses an NVIDIA specific hack to set __GL_YIELD to NOTHING. By setting "KWIN_NVIDIA_HACK" to "0" this behavior can be disabled.
KWin determines whether LIBGL_ALWAYS_INDIRECT has to be set by an external helper application and a driver whitelist of the drivers known to perform well with direct rendering. By setting the environment variable KWIN_DIRECT_GL to 1 the checks are not performed and LIBGL_ALWAYS_INDIRECT is not set.
This environment variable is only supported in 4.x.
By setting KWIN_GL_DEBUG to 1 the OpenGL rendering can be debugged visually. All geometries which are rendered are overlayed by a wireframe. The wireframe is not available in OpenGL ES 2.0. The environment variable is supported since 4.7.
The lanczos filter is controlled by the scale method in the advanced compositing settings and a blacklist of drivers known to break with this filter. The setting and the blacklist can be overruled by setting KWIN_FORCE_LANCZOS to 1. This environment variable is supported since 4.8.
By setting KWIN_OPENGL_INTERFACE to egl the OpenGL based compositor uses the EGL platform interface instead of the GLX. This environment variable is supported since 4.10.