Annotation Text Attributes

For an overview, see Primitives and Attributes.

Annotation text primitives and text primitives are the same except that annotation primitives must appear parallel to the viewing surface. Text primitives share some attributes and duplicate others to provide independent control over annotation text appearance. See Text Attributes for information about text primitives and attributes.

The annotation attributes and text attributes that affect annotation text primitives are:

 
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Annotation Text Alignment OC      PEXOCCSetATextAlignment
Annotation Text Height OC         PEXOCCSetATextHeight
Annotation Text Path OC           PEXOCCSetATextPath
Annotation Text Style OC          PEXOCCSetATextStyle
Annotation Text Up Vector OC      PEXOCCSetATextUpVector
Text Bundle Index OC              PEXOCCSetTextBundleIndex
    Character Expansion OC (ASF)  PEXOCCSetCharExpansion
    Character Spacing OC (ASF)    PEXOCCSetCharSpacing
    Text Color OC (ASF)           PEXOCCSetTextColor
    Text Color Index OC (ASF)     PEXOCCSetTextColorIndex
    Text Font Index OC (ASF)      PEXOCCSetTextFontIndex
    Text Precision OC (ASF)       PEXOCCSetTextPrecision
Text Bundle Table RA              Text Bundle Table
Text Font Table RA                Text Font Table
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The PEXlib annotation text primitives affected by the above attributes include:

 
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Annotation Text 3D          PEXOCCAnnotationText
Annotation Text 2D          PEXOCCAnnotationText2D
Encoded Annotation Text 2D  PEXOCCEncodedAnnoText
Encoded Annotation Text 2D  PEXOCCEncodedAnnoText2D
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See the sections referenced above for information about each of the annotation text primitives and the attributes that affect them.

Clipping of Annotation Text

Annotation text primitives are not displayed if their origin is outside of the currently defined clipping volume. If the origin is not clipped, then the string is clipped according to the text clipping rules (see Text Attributes) and origin-offset connection line enabled by the annotation text style attribute is clipped according to the line clipping rules (see Lines - Shading Attributes). Model clipping is considered when it is determined whether the origin is clipped, but model clipping is not applied to the string or the connection line.

HLHSR (Hidden Line/ Hidden Surface Removal) of Text

The treatment of annotation text strings during hidden surface computations depends on the HLHSR (Hidden Line/Hidden Surface Removal) mode you select and its implementation. Z-buffer algorithms usually perform the hidden surface computation on the 2D realization of the text string. Scan-line algorithms may determine visibility for text strings solely from the 3D positions of each string.

Text Bundle Index and Aspect Source Flag

Whenever you render an annotation text primitive, each of the text attributes is obtained directly from the current pipeline state or indirectly from a text bundle lookup table. Your application determines the source for the attribute by the current settings of the corresponding text aspect source flag or ASF's. If your application sets the attribute's ASF to the value PEXIndividual, then your application obtains the attribute value directly from the current pipeline state. If your application sets an attribute's ASF to the value PEXBundled, then your application obtains the attribute value from the current text bundle table. The text bundle index attribute indicates the text bundle table entry to be used. The ASF attributes are defined exactly as they are for PHIGS. Examples of the functionality and use of each is found in the PHIGS specification document. (See PHIGS functional specification, ISO/IEC 9592-1:1988, section 4.5.5)