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.TH "GET LOCATOR 3" 3P "29 February 1991"
.SH NAME
GET LOCATOR 3 \- retrieve the \s-2LOCATOR\s+2
event in the \s-2PHIGS\s+2 current event report.
.IX "Locator Input Devices" "GET LOCATOR 3"
.SH SYNOPSIS
.SS C Syntax
.ft B
.ta 1.25i 3i
.nf
void
pget_loc3 ( view_ind, loc_pos )
Pint	*view_ind;	\fI\s-2OUT\s+2 view index\fP
Ppoint3	*loc_pos;	\fI\s-2OUT\s+2 locator position\fP
.fi
.ft R
.SS Required PHIGS Operating States
(PHOP, WSOP, *, *)
.SH DESCRIPTION
.SS Purpose
\s-2GET LOCATOR 3\s+2 retrieves the current event report from the
\s-2PHIGS\s+2 state list when the event report contains a Locator event.
A \s-2LOCATOR\s+2 event consists of a position and a view index.
The position is the World Coordinate (\s-2WC\s+2) point corresponding to the
position on the workstation selected by the operator.
The view index is the index of the view representation used to
transform the selected position from Normalized Projection Coordinates
(\s-2NPC\s+2) to \s-2WC\s+2.
.LP
.SS C Output Parameters
.IP \fIview_ind\fP
\s-2PHIGS\s+2 sets the variable pointed to by \fIview_ind\fP to 
the index of the view representation used to transform
the \s-2NPC\s+2 locator position to a \s-2WC\s+2 position.
.IP \fIloc_pos\fP
\s-2PHIGS\s+2 sets the variable pointed to by \fIloc_pos\fP to 
the \s-2\&3D\s+2 world coordinate locator position corresponding to the
device coordinate position selected by the operator.
Ppoint3 is defined in phigs.h as follows:
.sp .4
.ta .5i +\w'Pfloat     'u +\w'x;     'u
.nf
typedef struct {
.sp .2
	Pfloat	x;	/* x coordinate */
	Pfloat	y;	/* y coordinate */
	Pfloat	z;	/* z coordinate */
.sp .2
} Ppoint3;
.fi
.SS Execution
When an input device in Event mode is triggered by the operator,
an event report is added to the input event queue.
The event report contains the identity and current measure of the device.
\s-2AWAIT EVENT\s+2 moves the measure of the oldest event in the input queue
to the current event report in the \s-2PHIGS\s+2 state list.
If the event is a Locator event, \s-2GET LOCATOR\s+2 or \s-2GET LOCATOR 3\s+2
is used to retrieve the contents of the event from the current event report.
.LP
The \s-2LOCATOR\s+2 position is computed by mapping the \s-2DC\s+2
workstation position selected by the operator to a \s-2WC\s+2 point.
The workstation transform is used to transform the \s-2DC\s+2
position to a \s-2NPC\s+2 position prior to transforming it to
\s-2WC\s+2.
See \s-2INITIALIZE LOCATOR\s+2 and
\s-2SET VIEW TRANSFORMATION INPUT PRIORITY\s+2 for a
description of how \s-2PHIGS\s+2 determines the view representation to use
to map the \s-2NPC\s+2 position to \s-2WC\s+2.
.LP
See \s-2INITIALIZE LOCATOR 3\s+2 for a description of the available
\s-2LOCATOR\s+2 devices and how their measure values are determined.
.SH ERRORS
.IP 003
Ignoring function, function requires state (\s-2PHOP, WSOP, *, *\s+2)
.IP 259
Ignoring function, the input device class of the current input report
does not match the class being requested
.SH SEE ALSO
.nf
.IP
.ta 0.5i
.SM "INITIALIZE LOCATOR 3 (3P)"
.SM "AWAIT EVENT (3P)"
.SM "GET LOCATOR (3P)"
.SM "SET VIEW TRANSFORMATION INPUT PRIORITY (3P)"
.fi
