Config.rst

Curv has an optional user-defined configuration file, which the curv command reads during startup.

You use the configuration file to customize the behaviour of Curv when viewing or exporting shapes. It works by providing default values for -O options which are given on the command line. Use curv --help to get a list of the current -O options.

Config File Location

The config file is normally located at ~/.config/curv. This can be a regular file, evaluated as a Curv syntax source file, or it can be a directory, which is evaluated using directory syntax.

The actual rules for locating the config file are more complicated, since Curv attempts to conform to the XDG Base Directory Specification:

• The environment variable $XDG_CONFIG_HOME defines the base directory relative to which the Curv config file is stored.
• If $XDG_CONFIG_HOME is either not set or empty, it defaults to $HOME/.config, unless $HOME is either not set or empty, in which case there is no Curv config file.
• The config file is named $XDG_CONFIG_HOME/curv.
• Curv ignores the $XDG_CONFIG_DIRS environment variable and the /etc/xdg directory.

The Config Namespace

The config value (the result of evaluating the config file) is a hierarchical namespace of configuration parameters, represented as a tree of records.

The top level names are export and viewer.

• export contains defaults for -O parameters used when exporting a shape using -o.
• viewer contains defaults for -O parameters used when viewing a shape.

Example

Here is an example. This is a text file stored at ~/.config/curv:

{
  export = {
    aa=4;
    colouring=#vertex;
  };
  viewer = {
    bg=black; // dark mode
  };
}

We have set the anti-aliasing parameter to 4 in order to obtain higher quality when performing an image export. But anti-aliasing is disabled when viewing objects (the default), for performance reasons.

Use vertex colouring when exporting X3D files.

The background colour is set to black when viewing shapes, because we prefer "dark mode". But the background colour is set to the default (white) when exporting PNG files, because we haven't overridden that value in export.