29.3. Environment variables

29.3. Environment variables
	Chapter 29. Settings File and Environment Variables

Similar to the values in the mevislab.prefs file, there are also settings that can be configured through environment variables, primarily to correct certain issues of the platform. We have collected some here that might be useful for you:

Name	Type	Description
General
`MLAB_ROOT`	Directory path	Sets 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 attempt 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	Forces MeVisLab to support 10-bit color depth in OpenGL if the auto-detection fails.
`MLAB_TTF_FONT`	File path	Overrides the font to use for font rendering. It must be a true type font.
`MLAB_DISABLE_BUSY_CURSOR`	Bool	Disables the display of a 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	Toggles the use of OpenGL shaders in SoView2D views.
Debugging
`MEVISLAB_DEBUGGER`	String	(Linux only) Sets a debugger command to call if MeVisLab crashes. The command is called with executable name and process ID.
`MLAB_DEBUG_PYTHON_IMPORT`	String	Prints additional information about imports occurring in Python code.
`IV_DEBUG_SHADER, IV_DEBUG_SHADER_LOG, and IV_DEBUG_SHADER_STRING`	Bool	(Used by SoShader framework) Receives additional log output to debug. shaders.
GVR (Giga Voxel Renderer) - OpenGL Compatibility
`GVR_NO_3D_TEXTURES`	Bool	Toggles the use of 3D textures in the GVR rendering.
`GVR_NO_GLSL`	Bool	Toggles the use of OpenGL shader language.
`GVR_NO_NONPOW2`	Bool	Toggles the use of textures that do not have a size that is a power of two.
`GVR_NO_GEOMETRYSHADER`	Bool	Toggles the use of geometry shaders.
`GVR_USE_FLOAT_LUT`	Bool	Uses look-up-tables with float values (instead of integer).
`GVR_NO_BINDLESS`	Bool	Toggles the use of bindless textures.
`GVR_PRINT_SHADER_WARNINGS`	Bool	Prints additional diagnostic messages when OpenGL shaders are compiled.
Special Settings
`MLAB_GPU_AFFINITY`	Integer	(Nvidia graphics only) Forces MeVisLab to run on a specific graphics card if several are installed on a system.
`MLAB_CUDA_DEVICE`	Integer	(Used by the PathTracer framework) Selects the CUDA device to perform calculations on.
`MLAB_NUMBER_CONCURRENT_PANEL_RENDERING`	Integer	(Used by RemotePanelRendering module) Serializes GPU access of parallel running processes.


29.2. Options in mevislab.prefs