GENERALIZED DRAWING PRIMITIVE -1(3P) — SUNPHIGS LIBRARY

NAME

GENERALIZED DRAWING PRIMITIVE -1 − create 2D GDP polyline set

SYNOPSIS

C Syntax

void
pgdp ( num_points, points, gdp_id, gdp_data )
Pintnum_points;number of points
Ppoint∗points;array of points
Pintgdp_id;gdp function identifier
Pgdprec∗gdp_data;data record pointer

FORTRAN Syntax

SUBROUTINE pgdp ( N, PXA, PYA, PRIMID, LDR, DATREC )
INTEGERNnumber of points (>= 0)
REALPXA(∗), PYA(∗)coordinates of points (MC)
INTEGERPRIMIDGDP identifier
INTEGERLDRdimension of data record array
CHARACTER∗80DATREC(LDR) data record

Required PHIGS Operating States

(PHOP, ∗, STOP, ∗)

DESCRIPTION

Purpose

GENERALIZED DRAWING PRIMITIVE -1 creates the polyline set GDP structure element.

C Input Parameters

num_points
The number of points passed in the points parameter.

pointsA pointer to a list num_points long of Ppoint structures containing x and y values in Modelling Coordinates (MC). Ppoint is defined in phigs.h as follows:

typedef struct {
Pfloatx;/∗ x coordinate ∗/
Pfloaty;/∗ y coordinate ∗/
} Ppoint;

gdp_id
The function identifier for this generalized drawing primitive is PUGDP_POLYLINE_SET, which is defined in phigs.h to be -1.

gdp_data
A pointer to a Pgdprec union, ugdp1_datarec, containing the information needed to perform the function specified by gdp_id. Pugdp0001rec is defined in phigs.h as:

typedef struct {
Pintn_sets;/∗ number of sets ∗/
Ppointlst∗sets;/∗ list of sets ∗/
} Pugdp0001rec; /∗ polyline set ∗/

The n_sets component specifies the number of sets of polylines in the polyline set. The sets component is a pointer to a list, n_sets long, of Ppointlst structures. Each Ppointlst structure defines one of the polylines in the set. Ppointlst is defined in phigs.h as follows:

typedef struct {
Pintnumber;/∗ number of points in the list ∗/
Ppoint∗points;/∗ pointer to list of points ∗/
} Ppointlst;

The number component specifies the number of points used to define a polyline. The points component is a pointer to a list, number long, of Ppoint structures which contain the x and y coordinates of each vertex of the polyline in MC.

FORTRAN Input Parameters

NNumber of points passed in the PXA and PYA arrays.

PXAAn array of N real values containing x coordinates in MC.

PYAAn array of N real values containing y coordinates in MC.

PRIMID
The function identifier for this generalized drawing primitive is PUGDPPLS, which is defined in phigs77.h to be -1.

LDRThe dimension of DATREC (returned by the PACK DATA RECORD subroutine).

DATREC
A GDP data record packed by the PACK DATA RECORD subroutine containing the information needed to perform the function specified by PRIMID.

The arguments passed to PACK DATA RECORD when PRIMID = PUGDPPLS should be as follows:

ILThe number of point lists, or sets of polylines, to be specified.

IAAn array of IL integers containing the end indices for each point list in the polyline set.

RLThe number of real values = 2 ∗ IA(IL).

RAAn array of RL real values containing the x and y coordinates of the polyline set. Elements 1 through IA(IL) contain the x components of the polyline set. Elements IA(IL) + 1 through 2 ∗ IA(IL) contain the y components of the polyline set.

The first polyline in the set is defined by the x coordinates in RA from 1 to IA(1) and by the y coordinates in RA from IA(IL) + 1 to IA(IL) + IA(1). The second polyline in the set is defined by the x coordinates in RA from IA(1) + 1 to IA(2) and by the y coordinates in RA from IA(IL) + IA(1) + 1 to IA(IL) + IA(2).

SLThe number of strings = 0.

Execution

A polyline set is a set of unconnected polylines defined by a set of point sequences; each point sequence in the set generates connected line segments. When the structure is traversed, the GDP element draws the specified number of polylines using the points in the GDP data record. The current values of all polyline attributes will be applied to the polyline set when it is drawn.

The points are specified in MC. These may be any coordinate units that are convenient to the application. At traversal, these coordinates are transformed by the current local and global modelling transformations, the view representation selected by the current view index, and the workstation transformation current on the workstation to which the structure is posted.

The array of points passed to this subroutine in addition to the GDP data record is not used by the polyline set GDP.

Attributes Applied

The attributes listed below are used to display the GENERALIZED DRAWING PRIMITIVE -1 structure element. The Aspect Source Flags (ASFs) tell where to access the output display attributes. These attributes can come directly from the traversal state list, or they can be accessed indirectly, using the appropriate index in the traversal state list and the corresponding bundled representation in the workstation state list.

polyline colourpolyline colour index ASF
linewidth scale factorlinewidth scale factor ASF
linetypelinetype ASF
polyline shading methodpolyline shading method ASF
curve approximation criteriacurve approximation criteria ASF
polyline index
depth cue index
name set

ERRORS

005Ignoring function, function requires state (PHOP, ∗, STOP, ∗)

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