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.TH "SET PATTERN REFERENCE POINT" 3P "29 February 1991"
.SH NAME
SET PATTERN REFERENCE POINT \- create structure element to set the current pattern reference point
.IX "Attributes, Filled Area Interior Attributes" "SET PATTERN REFERENCE POINT"
.IX "Filled Area Interior Attributes" "SET PATTERN REFERENCE POINT"
.IX "Pattern Fill" "SET PATTERN REFERENCE POINT"
.SH SYNOPSIS
.SS C Syntax
.ft B
.ta 1.25i 3i
.nf
void
pset_pat_ref_point ( ref_pt )
Ppoint	*ref_pt;	\fIpattern reference point\fP
.fi
.ft R
.SS Required PHIGS Operating States
(PHOP, *, STOP, *)
.SH DESCRIPTION
.SS Purpose
.LP
.SM "SET PATTERN REFERENCE POINT"
creates a structure element
containing a value for the \fIcurrent pattern reference point\fP attribute.
The structure implicitly resets the \fIcurrent pattern reference vectors\fP
attribute as well.  When the interior style is \s-2PATTERN\s+2,
these attributes apply to the following output primitives:
.ta .5i +1.75i
.nf
	\(bu  \s-2FILL AREA\s+2	\(bu  \s-2NON-UNIFORM B-SPLINE SURFACE\s+2 
	\(bu  \s-2FILL AREA 3\s+2	\(bu  \s-2SET OF FILL AREA SET 3 WITH DATA\s+2
	\(bu  \s-2FILL AREA SET\s+2	\(bu  \s-2TRIANGLE STRIP 3 WITH DATA\s+2
	\(bu  \s-2FILL AREA SET 3\s+2	\(bu  \s-2QUADRILATERAL MESH 3 WITH DATA\s+2 
	\(bu  \s-2FILL AREA SET 3 WITH DATA\s+2
.fi
.LP
\fBNote:\fP This function places the appropriate data in the
Central Structure Store and in \s-2PEX-SI\s0 archives,
but the structure element is currently ignored during traversal.
.LP
If the current edit mode is \s-2INSERT\s+2, a
.SM "SET PATTERN REFERENCE POINT"
element is inserted into the currently open
structure after the element pointed to by the current element pointer. If
the edit mode is \s-2REPLACE\s+2, the new element
replaces the element pointed to by the element pointer. In either case, the
element pointer is updated to point to the new element.
.SS C Input Parameter
.IP \fIref_pt\fP
The \fIpattern reference point\fP is given in Modelling Coordinates \s-2(MC)\s+2,
using a \s-2\&2D\s+2 shorthand;
0 is used as the
.I z
coordinate.  The Ppoint type is defined in phigs.h as:
.nf
.ta .5i +\w'Phalfspace  'u +\w'half_spaces;   'u
.sp .3
typedef struct {
.sp .2
	Pfloat	x; 	/* x coordinate */
	Pfloat	y; 	/* y coordinate */
.sp .2
} Ppoint;
.sp .3
.fi
.SS Execution
When the \s-2SET PATTERN REFERENCE POINT\s+2 element is traversed,
the current pattern reference point
entry in the traversal state list is set to the \fIx\fP and \fIy\fP
values contained in this element, and the \fIz\fP value 0.  The
current pattern reference vectors are set to (1,0,0) and (0,1,0).
When the interior style
(either individual or bundled, as selected by the \fIcurrent interior style \s-2ASF\s+2\fP)
is set to \s-2PATTERN\s+2, these attributes are used in conjunction with
the current pattern size for the area-defining primitives
that follow in the structure network.
.SH ERRORS
.IP 005
Ignoring function, function requires state (PHOP, *, STOP, *)
.SH SEE ALSO
.nf
.IP
.ta 0.5i
.SM "INQUIRE PATTERN FACILITIES (3P)"
.SM "SET PATTERN SIZE (3P)"
.SM "SET PATTERN REPRESENTATION (3P)"
.SM "SET PATTERN REFERENCE POINT AND VECTORS (3P)"
.fi
