.\"
.\" $XConsortium: p149,v 5.3 94/04/17 20:56:09 hersh Exp $
.\"
.\" 
$XMCOPY
.\" Copyright (c) 1990, 1991 by Sun Microsystems, Inc. and the X Consortium.
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.\" 1. Substitute PHIGS+ function name (in CAPS) for "PNAME" in line below:
.ds pN INQUIRE LIGHT SOURCE FACILITIES
.TH "\*(pN" 3P+ "15 August 1991"
.SH NAME
\*(pN \-
inquire list of workstation light source facilities for a
specified workstation type
.IX "Inquiry functions" "INQUIRE LIGHT SOURCE FACILITIES"
.IX "PHIGS Extension Functions" "\*(pN"
.IX "Lighting" "INQUIRE LIGHT SOURCE FACILITIES"
.SH SYNOPSIS
.SS C Syntax
.ft B
.ta 1.25i 3i
.nf
.\" 6. Insert C syntax below
void
pinq_light_src_facs ( type, length, start, error_ind, facilities, total_length)
Pint	type;	\fIworkstation type\fP
Pint	length;	\fIlength of application list \fP
Pint	start;	\fIstarting position\fP
Pint	*error_ind;	\fIOUT error indicator\fP
Plight_src_facs	*facilities;	\fIOUT light source facilities\fP
Pint	*total_length;	\fIOUT length of list in PHIGS\fP
.fi
.ft R
.SS Required PHIGS Operating States
(PHOP, *, *, *)
.SH DESCRIPTION
.SS Purpose
.LP
\s-2INQUIRE LIGHT SOURCE FACILITIES\s+2 obtains a list of workstation
light source facilities.
.SS C Input Parameters
.IP \fItype\fP
The workstation type for which the light source facilities are being inquired.
.IP \fIlength\fP
The number of \fIints\fR in the \fIfacilites\(->types\fR output parameter for which the 
application has allocated memory. \fIlength\fR is the number of list elements
that the system can return in \fIfacilites\(->types.ints\fR.
If a value of 0 is used here, no data will be returned in the
\fIfacilites\(->types.ints\fR list, but the total number of elements
will be returned in \fItotal_length\fR.
.IP \fIstart\fP
Starting position of inquiry.  The elements in the list, beginning
with the item number specified by \fIstart\fR, are copied sequentially into 
\fIfacilites\(->types.ints\fR until \fIfacilites\(->types.ints\fR is full
or all the elements have been copied.
.SS C Output Parameters
.IP \fIerror_ind\fP
A pointer to the location to store the error number.
.IP \fIfacilities\fP
A pointer to the location in which to return the light source
facilities. Plight_src_facs is defined as:
.nf
.ta .5i +\w'Pint_list     'u +\w'num_pred_inds;     'u
.sp .4
typedef struct {
.sp .2
	Pint_list	types;	/* types of light source supported */  
	Pint	max;	/* max. no. of simultaneously active lights */
	Pint	num_pred_inds	/* number of predefined bundles */
.sp .2
} Plight_src_facs;
.fi
.IP
\fItypes\fR is a pointer to the types of light sources that are supported:
.ta .5i +.5i
.nf
	1	PLIGHT_AMBIENT
	2	PLIGHT_DIRECTIONAL
	3	PLIGHT_POSITIONAL
	4	PLIGHT_SPOT
.fi
.sp
Pint_list is defined in phigs.h as follows:
.nf
.ta .5i +1i +1.25i
.sp .4
typedef struct {
.sp .2
	Pint	num_ints;	/* number of Pints in list */
	Pint	*ints;	/* list of integers        */
.sp .2
} Pint_list;
.fi
.IP
The \fInum_ints\fR component specifies the number of elements in the list.
The \fIints\fR component is a pointer to a list \fInum_ints\fR long.
.IP
Prior to calling this function, the \fIints\fR field of the Pint_list
structure must contain a pointer to an application
supplied buffer.  This buffer must be at least as large as the 
corresponding length parameter.
.IP
The light types supported are:
.sp
.nf
.ta .5i +\w'0  'u +\w'WCS_Vector  'u
1	Ambient	A light source that affects all surface primitives uniformly.
			Ambient light sources have only a color attribute.
2	WCS_Vector	A light source that is specified in world coordinates
			with a color and a direction vector.
3	WCS_Point	A light source that is specified in world coordinates with
			a color, a position, and two attenuation coefficients.
4	WCS_Spot	A light source that is specified in world coordinates with
			a color, a position, a direction vector, a concentration exponent,
			two attenuation coefficients, and a spread angle.
.sp
.fi
.IP \fItotal_length\fP
A pointer to an integer in which the system returns the total number of elements
in the list.  This is the value required for \fIlength\fR if all elements in the
list are to be returned.
.SS Execution
If the inquired information is available, the error indicator is returned
as zero and values are returned in the output parameters.
.LP
If the inquired information is not available, the values returned in
the output parameters are undefined and the error
indicator is set to one of the following error numbers to indicate
the reason for nonavailability.
.LP
Since this is an inquiry function, \s-2ERROR HANDLING\s+2 is not invoked
when an error is detected by this function.
.SH ERRORS
.IP 002
Ignoring function, function requires state (\s-2PHOP,*,*,*\s+2)
.IP 051
Ignoring function, this information unavailable for this workstation type
.IP 052
Ignoring function, workstation type not recognized by the implementation
.IP 059
Ignoring function, the specified workstation does not have output capability
(i.e. the workstation category is neither \s-2OUTPUT\s+2, \s-2OUTIN\s+2, nor \s-2MO\s+2)
.IP 062
Ignoring function, this information is not available for this
\s-2MO\s+2 workstation type
.SH SEE ALSO
.nf
.IP
.ta 0.5i
.SM "SET LIGHT SOURCE REPRESENTATION (3P+)"
.SM "INQUIRE LIST OF LIGHT SOURCE INDICES (3P+)"
.SM "INQUIRE LIGHT SOURCE REPRESENTATION (3P+)"
.SM "INQUIRE PREDEFINED LIGHT SOURCE REPRESENTATION (3P+)"
.fi
