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Clutter automatically checks environment variables during its initialization. These environment variables are meant as debug tools, overrides for default behaviours or to address known hardware issues:
| CLUTTER_TEXT_DIRECTION | Forces the text direction of every Pango layout inside Clutter. Valid values are: ltr or rtl | 
| CLUTTER_SHOW_FPS | Prints out the frames per second achieved by Clutter. | 
| CLUTTER_DEFAULT_FPS | Sets the default framerate. | 
| CLUTTER_DISABLE_MIPMAPPED_TEXT | Disables mipmapping when rendering text. | 
| CLUTTER_FUZZY_PICK | Enables "fuzzy picking". | 
| CLUTTER_DEBUG | Enables debugging modes for Clutter. | 
| COGL_DEBUG | Enables debugging modes for COGL. | 
On the GLX backend there is also:
| CLUTTER_VBLANK | Selects the sync-to-vblank mode to be used. Valid values are: none, dri or glx | 
Similarly to the environment variables, Clutter also installs command line switches that are parsed during initialization:
| --clutter-show-fps | Equivalent of CLUTTER_SHOW_FPS. Prints the current rendering speed in frames per second. | 
| --clutter-default-fps=FPS | Equivalent of CLUTTER_DEFAULT_FPS. Sets the default framerate. | 
| --clutter-text-direction=DIRECTION | Equivalent of CLUTTER_TEXT_DIRECTION. Sets the direction for the text. | 
| --clutter-disable-mipmapped-text | Equivalent of CLUTTER_DISABLE_MIPMAPPED_TEXT. Disables mipmapping when rendering text. | 
| --clutter-use-fuzzy-picking | Equivalent of CLUTTER_FUZZY_PICK. Enables "fuzzy" picking. | 
| --clutter-debug=FLAGS | Equivalent of CLUTTER_DEBUG. Sets FLAGS as the Clutter debugging flags. | 
| --clutter-no-debug=FLAGS | Unsets FLAGS from the Clutter debugging flags. | 
| --cogl-debug=FLAGS | Equivalent of COGL_DEBUG. Sets FLAGS as the COGL debugging flags. | 
| --cogl-no-debug=FLAGS | Unsets FLAGS from the COGL debugging flags. | 
The X11 backends also have the following command line options:
| --display=DISPLAY | Sets the X11 display to use. | 
| --screen=SCREEN | Sets the X11 screen number to use. | 
| --synch | Make X11 calls synchronous. | 
The GLX backend also has the following command line option:
| --vblank=METHOD | Equivalent of CLUTTER_VBLANK. Sets the sync-to-vblank method to be used. |