local.c

Intro/: Directory containing introductory examples. HelloWorld.c A simple program that draws a bo

#include <phigs.h>			/* get HP-PHIGS definitions for C */
#include <stdio.h>			/* get standard I/O definitions */
#include <math.h>			/* link with library "-lm" */

main()					/* file "Local.c" */
{
    Pint	WorkstnID = 1;		/* workstation identifier */
    Pint	ConnID;			/* connection identifier */
    Pint	WorkstnType = POIDDX;	/* out/in, direct, dbl bfr, Xwindow */
    Pint	TheStructure = 1;	/* structure ID (chosen by user) */
    Pfloat	KnotVals[13];		/* array for knot vectors */
    Pfloat_list	Knots;			/* list of floats */
    Pint	NumKnots, NumSegs;	/* number of knots, segments */
    static Ppoint3 CtrlPts[10] = {
	{0.1, 0.1, 0.0}, {0.1, 0.5, 0.0}, {0.3, 0.8, 0.0}, {0.2, 0.9, 0.0},
	{0.5, 0.9, 0.0}, {0.3, 0.2, 0.0}, {0.6, 0.0, 0.0}, {0.7, 0.2, 0.0},
	{0.7, 0.7, 0.0}, {0.9, 0.9, 0.0}};
    Pctrl_point3_list	CtrlPtList;	/* list of control points */
    static Ppoint_list3 MarkerList =	/* for polymarkers */
	{10, CtrlPts};
    Pcurve_geom_spline	Curve;		/* the spline definition */
    int		I;			/* loop control variable */

    popen_phigs((char *) stderr, 0);	/* errors go to "stderr" */
    pescape_u4("/dev/screen/phigs_window", &ConnID);
    popen_ws(WorkstnID, (void *) ConnID, WorkstnType);
    popen_struct(TheStructure);
    Curve.order = 3;
    pset_marker_type(PMARKER_ASTERISK);
    pset_marker_size(4.0);
    MakeKnotVector(Curve.order, 10, &KnotVals, &NumKnots, &NumSegs);
    Knots.num_floats = NumKnots;
    Knots.floats = KnotVals;
    Curve.knots = Knots;
    Curve.low_limit = 0.0;
    Curve.high_limit = (float) NumSegs;
    CtrlPtList.rationality = PB_SPLINE_NON_RATIONAL;
    CtrlPtList.num_points = 10;
    CtrlPtList.points.point3 = CtrlPts;
    Curve.ctrl_points = CtrlPtList;
    for (I = 1; I <= 5; I++) {
	CtrlPts[6].y = I * 0.1;		/* change one control point */
	ppolymarker3(&MarkerList);
	pnon_uniform_b_spline_curve3(&Curve);
    }
    pclose_struct();
    ppost_struct(WorkstnID, TheStructure, 1.0);
    pclose_ws(WorkstnID);
    pclose_phigs();
}
/****************************************************************************/
MakeKnotVector(Order, NumCtrlPts, KnotVector, NumKnots, NumSegs)
Pint	Order;			/* order of the spline */
Pint	NumCtrlPts;		/* number of control points in the curve */
Pfloat	*KnotVector;		/* the returned knot vector */
Pint	*NumKnots;		/* number of knots in vector */
Pint	*NumSegs;		/* number of segments in curve */
{    
    int	I;			/* loop control variable */
    int	Knot;			/* array index */
    
    *NumSegs = NumCtrlPts + 1 - Order;	/* calculate number of segments */
    *NumKnots = Order + NumCtrlPts;	/* calculate number of knots */
    Knot = 0;				/* initialize the index */
    /*--- define the multiples at the beginning of the knot vector ---------*/
    for (I = 1; I <= Order; I++)
	KnotVector[Knot++] = 0.0;		/* define the element */
    /*--- define the middle chunk ------------------------------------------*/
    for (I = 1; I <= *NumSegs; I++)
	KnotVector[Knot++] = (float) I;		/* define the element */
    /*---- define the multiples at the end of the knot vector ---------------*/
    for (I = 1; I <= Order; I++)
	KnotVector[Knot++] = (float) *NumSegs;	/* define the element */
}