Angle Labels
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Dialog Box - called from: Display Menu

Angles are labeled with their values in degrees. A circular arc is drawn between the two central-ligand bonds defining the angle, and the label is drawn over the midpoint of this arc. Note that this arc is 3-dimensional, and its projection may not be circular. The radial position of arc and label are defined with the Fraction of short bond edit box. If this value is 0.5, for example, the arc will be drawn half-way out from the central atom to the atom at the end of the shorter bond.

Angles are located automatically, from the Specifications (below). Note that the location is done in the calculation, not plotting, so changing the specifications will require Recalculation (Dialog Bar - Left or File menu).

Drawings should be kept simple when this option is used, as only a limited number of angle labels will be intelligible. Typically this option would be used in conjunction with the Sphere boundary option, to illustrate the coordination of a single atom.

The Blank interval causes the bond to start and end short of the actual center line of the bonds. Using this interval may improve the appearance, especially if stick bonds, instead of line bonds, are used.

You can specify the number of figures to the right of the decimal with the Decimals item. The labels will be stripped of trailing blanks and centered on the projection of the midpoint of the arc, unless the Offsets are non-zero.

If the Background is opaque, each letter will lie on a small block of the designated color; this usually makes the labels easier to read. Some other programs may not be able to reproduce these opaque blocks in Metafile or PICT file output.

If the Scale box is checked, the letters in the labels in printed or file output will be rescaled to keep the same approximate proportions with respect to atoms, bonds, etc. as in the screen view.

The Linewidth gives the width of the arc, which is always a line even in 3D Drawing mode. The line will have the same color as the letters; this color can be specified in this dialog. [Macintosh only ] In the 3D Drawing mode on the Macintosh it is not possible to set linewidths - all lines are one pixel wide.

Use PostScript font. This allows you to enter a character string for PostScript fonts supported by a PostScript printer if such fonts do not appear in the standard system font dialog called up by the Font button. This character string usually specifies the weight (normal, bold) and slant (italic, oblique) of the font, but not the size, which is specified in the Font dialog. Certain PostScript typefaces are standard, and should be present on most PostScript printers.

Use the color options in this dialog, not the color options in the Font dialog to set the color of the letters. Letters are always solid black in black-and-white display or output. See Input Colors/Patterns/Pens for general aspects of color input.

Specifications. These are given in terms of coordination of a single central atom. Angles will be found around all atoms of the given Type. The Maximum Angle can be used to exclude near-180-degree angles in octahedra, for example. The angles are located at calculation, not plot time, so changing specifications will require Recalculation (Dialog Bar - Left or File menu).

"Deleting " angle labels. All angles around the atoms of the specified type(s) will be located. However, individual angles can be "deleted", or actually marked for non-plotting. This is done by clicking successively on the three atoms in the order outer-central-outer. In the Generated Atom Data dialog, there then appears an Angle checkbox. Unchecking will cause non-plotting of the angle. A list of the non-plotting angles is saved in the data (.str) file. The Show All button allows restoration of all non-plotting angles, and the Delete All button marks all angles for non-plotting. Individual non-plotting angles can be restored by clicking on the atoms and checking the Angle box in the Generated Atom Data dialog.

Labels on individual angles can be moved onscreen with a special cursor mode controlled by the Move Labels button in the Dialog Bar - Right. The Zero Displacements button in this dialog will remove the displacements on all angle labels.

Angle labels are not supported for Pen Plot output.

Note that in 3D Drawing mode the labels have an absolute position in space, including the x (front-back) coordinate. They are arbitrarily plotted 0.5 Angstroms in front of the arc, but they may still actually intersect or interpenetrate with the arc in some cases.