28.3. Environment variables

28.3. Environment variables
	Chapter 28. Settings File and Environment Variables

Similar to the values in the mevislab.prefs file there are also some settings which can be set though environment variables, mostly to correct some misbehavior of the platform. We have collected some here that might be of use for you:

Name	Type	Description
General
`MLAB_ROOT`	path	The path where the MeVisLab packages are installed. This must be set if you call some shell scripts that, e.g, create compiler projects or generate installers. The Windows installer will set this automatically.
Fixes
`MLAB_FORCE_MESA`	bool	(Windows only) If set to 1, MeVisLab will always try to use the Mesa software OpenGL driver supplied with the SDK. This can be used if the system OpenGL driver does not work.
`MLAB_QT_OPENGL_WIDGET`	"old" or "new"	Qt deprecated the old OpenGL widget with Qt 5. Since the first versions of the new widget had problems on some systems, you can switch back to the old widget by setting the value "old" - but since the widget is deprecated you might run into other problems.
`MLAB_OPENGL_10BIT`	bool	Force MeVisLab to support 10bit color depth in OpenGL in case the auto-detection fails.
`MLAB_TTF_FONT`	path	Override font to use for font rendering. Must be a true type font.
`MLAB_DISABLE_BUSY_CURSOR`	bool	(Linux and Windows only) Disable display of busy cursor when MeVisLab is calculating.
`MLAB_SOQT_ROUNDUP_WHEEL_DELTA`	bool	Fixes misbehaving mouse wheel in Inventor views (for some buggy mouse drivers).
`SOVIEW2D_NO_SHADER`	bool	Do not use OpenGL shaders in SoView2D views.
Debugging
`MEVISLAB_DEBUGGER`	string	(Linux only) Set debugger command to call if MeVisLab crashes. Command is called with executable name and process ID.
`MLAB_DEBUG_PYTHON_IMPORT`	string	Print additional information about imports happening in Python code.
`IV_DEBUG_SHADER, IV_DEBUG_SHADER_LOG, and IV_DEBUG_SHADER_STRING`	bool	(Used by SoShader framework) Get additional log output to debug shaders.
GVR (Giga Voxel Renderer) - OpenGL Compatibility
`GVR_NO_3D_TEXTURES`	bool	Do not use 3D textures in the GVR rendering.
`GVR_NO_GLSL`	bool	Do not use OpenGL shader language.
`GVR_NO_NONPOW2`	bool	Do not use texture that do not have a size that is a power of two.
`GVR_NO_GEOMETRYSHADER`	bool	Do not use geometry shaders.
`GVR_USE_FLOAT_LUT`	bool	Use look-up-tables with float values (instead of integer).
`GVR_NO_BINDLESS`	bool	Do not use bindless textures.
`GVR_PRINT_SHADER_WARNINGS`	bool	Prints additional diagnostic messages when OpenGL shaders are compiled.
Special Settings
`MLAB_GPU_AFFINITY`	int	(NVidia graphics only) Force MeVisLab to run on a specific graphics card if several are installed on a system.
`MLAB_CUDA_DEVICE`	int	(Used by PathTracer framework) Select the CUDA device to do calculations on.
`MLAB_NUMBER_CONCURRENT_PANEL_RENDERING`	int	(Used by RemotePanelRendering module) Serialize GPU access of parallel running processes.


28.2. Options in mevislab.prefs		Chapter 29. Coding Style Guide