TrueType to Unigraphics Font Conversion - Technical Details

This page provides in-depth information, how TrueType fonts will be converted to Unigraphics fonts. For your reference, download arial.zip (102 KB) - containing a subset from a conversion of Arial.ttf:

• Arial_Regular_ISO_medium.fnt
• Arial_Regular_Unicode_medium.fnt

How conversion is done

Font Header

Font header information is directly derived from TrueType header information. Contrary to common UG practice, the box-height is not 127 (pre V14) or 16383 (V14 and above). We use the native TrueType value instead, avoiding a lot of scaling work. This works nicely in UG, but some ill conditioned user-apps, directly reading font source files might fail.

Spacing and Kerning

Variable character spacing is used, thus translating TrueType character advance widths to UG character widths. For best matching of character spacing between TT and UG fonts, you should set Preferences - Lettering - Character Space = 0.
Overlap shifting/Kerning cannot be applied because of fundamental differences between both font formats.

Characters

Two types of files are provided: ISO and Unicode.
 

• ISO: Character codes 32-127 and 160-255 are converted, as far as corresponding outlines are found in the TrueType font.
• Unicode: All characters, available in the TrueType font are translated.
  Note: Character codes > 255 cannot be used in UG. But you may want to customize your ISO font with $-chars, using the outlines of special Unicode symbols.

For additional information on character codes and fonts in UG, please take a look at Steven Vickers very comprehensive page International Fonts for Unigraphics.

Outlines

Lines are converted as such, bezier curves are split into atomic bezier arcs and approximated by line segments (coarse, medium, fine).
Contrary to TT fonts, UG fonts do not allow negative point coordinates. A transformation is performed, ensuring all x and y values are positive at least for ISO characters.

Filling

Filling of outlines is done by straight horizontal lines. In your order you have to specify the number of lines per character height, if filling is desired. The number of lines depends mainly on your requirements: A low number will result in a fast font as UG has to draw only a small number of strokes - a large number will provide nicely filled shapes of the characters.

What to do with '.fnt' files

Before you can use the new font in UG, the '.fnt'-files have to be translated with the 'ugfontc' utility into '.fnx'-files and moved to your UGII_CHARACTER_FONT_DIR. For detailed information on ugfontc please see the UG documentation.
Note: Maximum filename-length for ugfontc is 30 characters, so you may have to shorten the filename of the shipped '.fnt'-files before.