Usage:
2dlabels  action  arguments

Usage:
2dlabels write  filename

Usage:
2dlabels read  filename

2dlabels is the command-line implementation of 2D Labels, which allows adding text, symbols, and arrows to the display. This is useful for annotating images and movies. The labels exist in the X,Y plane (the plane of the screen) and do not have a “depth” (Z-coordinate); they appear in front of any graphics displays and will not move when models are moved. 2D labels can be of multiple colors and sizes, and they can be faded in or out. See the video mini-example. See also: label, colorkey, labelopt, rlabel, windowsize, movie-related commands

Text and symbols are laid out horizontally, whereas the arrows can be oriented in any direction in the plane. (Although symbols also include some arrows in specific orientations, they cannot be oriented arbitrarily.) For 3-dimensional arrows, see BILD format.

2D label information is saved in sessions. 2D labels can also be saved (collectively) to a separate label file with the write keyword or imported from such a file with read. These keywords cannot be truncated.

2D labels created with the 2D Labels graphical interface are assigned names label2d_id_0, label2d_id_1, label2d_id_2, etc. in order of creation, allowing their subsequent modification with the 2dlabels command.

The action can be one of the following:

• create - create a 2D text/symbol label
• change - modify a 2D text/symbol label
• delete - delete a 2D text/symbol label
• acreate (synonym arrowcreate) - create a 2D arrow
• achange (synonym arrowchange) - modify a 2D arrow
• adelete (synonym arrowdelete) - delete a 2D arrow

The name is required and serves as an identifier for subsequently modifying or deleting the 2D text/symbol label. The label-contents (default nothing) can include letters, numbers, symbols from the keyboard; additional symbols can be copied (for example, from here) and pasted into the command line, or indicated with unicode character codes or character names. Unicode examples:

• text 'the \u03b1 subunit'    gives    the α subunit
• text 'reactants \N{RIGHTWARDS ARROW} products'    gives    reactants → products

Spaces and quote marks can be included by enclosing the entire label-contents in single or double quote marks. Carriage returns are indicated with \n. The label-color can be any color name that specifies a single color (default white). Any transparency in the color is ignored. The font-size must be an integer greater than zero (default 24). The font-style can be normal (default), bold, italic, or bold italic, where the latter should be enclosed in single or double quotation marks. The font-typeface can be serif, fixed, or sans serif (default), where the latter should be enclosed in single or double quotation marks. The x-position and y-position are the X and Y coordinates of the lower lefthand corner of the label (defaults are 0.5 and 0.5). The X axis is horizontal and the Y axis is vertical, and both range from 0 to 1 in the visible portion of the window. It is possible to place a label partially or completely outside the visible area, however. A label background (colored rectangle under the label text) can be shown with the bgColor option by setting rectangle-color to any color name that specifies a single color (default None, no label background). The colored rectangle will extend rectangle-padding pixels (default 9) beyond the text in each direction (left, right, top, bottom), and an additional outline in white for dark rectangle colors or black for light rectangle colors will be drawn around the rectangle if rectangle-outline-width > 0 is specified (default 0, no outline). The visibility option specifies whether the label should be displayed. An invisible label can be faded in or a visible label faded out using change.

The 2D label to modify is specified by the name it was assigned with create. All 2D labels collectively can be specified with * (asterisk) instead of name. The label can be faded in or out gradually using the visibility option with frames specified. All other options are as described above for create, except the defaults are to leave the current label unchanged.

The 2D label to delete is specified by the name it was assigned with create. All 2D labels collectively can be specified with * (asterisk) instead of name.

The name is required and serves as an identifier for subsequently modifying or deleting the 2D arrow. The keywords acreate and arrowcreate are interchangeable. The start and end arguments are required and specify the the start and end (tip) locations of the arrow in the X,Y plane, where the X axis is horizontal and the Y axis is vertical, and both range from 0 to 1 in the visible portion of the window. The X and Y coordinates should be separated by a comma only (no spaces). The arrow-color can be any color name that specifies a single color (default white). The weight (default 1.0) is a scale factor for the overall thickness of the arrow. The head option specifies arrowhead style. The visibility option specifies whether the arrow should be displayed. An invisible arrow can be faded in or a visible arrow faded out using achange.

The keywords achange and arrowchange are interchangeable. The 2D arrow to modify is specified by the name it was assigned with acreate. All 2D arrows collectively can be specified with * (asterisk) instead of name. The start, end, color, weight, and head options are as described above for acreate, except the defaults are to leave the current arrow unchanged. The arrow can be faded in or out gradually using the visibility option with frames specified.

The keywords adelete and arrowdelete are interchangeable. The 2D arrow to delete is specified by the name it was assigned with acreate. All 2D arrows collectively can be specified with * (asterisk) instead of name.