The use of the existing commands is illustrated by the following example (user input is high-lighted):
O > mask_read Mask> File name of mask to be read: m12a.mask Mask> Parameters as read from the mask file: Mask> Grid ................. 100 110 64 Mask> Origin ............... 31 45 8 Mask> Extent ............... 48 53 61 Mask> Cell axes ............ 91.80 99.50 56.50 Mask> Cell angles .......... 90.00 90.00 90.00 Mask> Mask read OK. Mask> 33221 points set in mask Mask> 155184 points total O > mask_setup Mask> Mask value to set \& display [ 1 1]: 1 0 Mask> Radius in which pixels are set \& displayed [ 1.0 8.0]: 2. 9. Mask> Radius in which to contour [ 10.0]: Mask> Contour colour? [red]: O > mask_on O > mask_off O > mask_contour O > mask_write Mask> File name of mask to be written: m12a_edit.mask O >
The Mask_read and Mask_write commands read and write out mask files. Only one mask file can be stored at a time (at present). The Mask_setup command set parameters used with the Mask_on and Mask_off commands that control what will be displayed and how the mask is to be edited. In the above example, both Mask_on and Mask_off will display non-mask grid points within 10Å of a moving atom as dots. When editing is set `on' by the Mask_on command, points 1.0Å from the moving atom will be set as lying within the mask. This will have the affect of erasing the dots drawn on the display. The setup values used here are, therefore, suitable for detecting holes in the mask and for removing them.
The commands Mask_on and Mask_off start the display of the mask. Both commands require the user to identify an atom that can be moved around in space. Dots will appear that represent grid points either within or outside the mask depending on the values set with Mask_setup. If Mask_off is active, then as the atom is moved around, the mask object is updated but the mask is not changed. When Mask_on is active, the mask gets changed and grid points within the specified radius are reset, according to the Mask_setup values. Activating Mask_on, deactivates Mask_off and vice versa. When either command is active, Mask_setup can be activated to change the current values.