|GPCHUB (up, base)|
Use GPCHUB to insert a Set Character Up and Base Vectors structure element into the open structure following the element pointer or to replace the element pointed at by the element pointer with a Set Character Up and Base Vectors structure element depending on the current edit mode.
During structure traversal, this structure element sets the current character up vector and base vector entries in the graPHIGS API traversal state list to the specified values.
The character up vector specifies the direction of the font coordinate y-axis within the text reference coordinate system. The character base vector specifies the direction of the font coordinate x-axis within the text reference coordinate system. The vectors need not be perpendicular to one another.
This attribute sets the same traversal state as the Set Character Up Vector (GPCHUP) subroutine.
The traversal default value for character up vector is 0.0, 1.0 and the traversal default value for character base vector is 1.0, 0.0.
If the character up and base vector are invalid, then the up vector defaults to 0.0, 1.0, and the base vector value defaults to 1.0, 0.0.
The graPHIGS API normalizes the specified vectors. If the application later inquires the content of this structure element, then the graPHIGS API returns the normalized vectors not the original vectors specified by this subroutine.