orders.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 "Orders.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) */
    static Plimit Window = {0.0, 1.0, 0.0, 1.0};/* \  to define	the */
    Plimit	Viewport;			/*  > view mapping  */
    Pview_map	ViewMapping;			/* /  matrix	    */
    Pmatrix	ViewMapMat;			/* \		      */
    static Pmatrix ViewOriMat = {1.0, 0.0, 0.0,	/*  \  to define      */
				 0.0, 1.0, 0.0,	/*   > the view	      */
				 0.0, 0.0, 1.0};/*  /  representation */
    Pview_rep	ViewRep;			/* /		      */
    Pint	Linear = 2, Quadratic = 3, Cubic = 4, Quartic = 5, Quintic = 6;
    char	OrderNames[][18] = {	/* names of the splines' orders */
	"Linear/Quadratic", "Linear/Cubic", "Linear/Quartic",
	"Linear/Quintic"};
    Pfloat	KnotVals[13];		/* array for knot vectors */
    Pfloat_list	Knots;			/* list of floats */
    Pint	NumKnots, NumSegs;	/* number of knots, segments */
    static Ppoint3	CtrlPts[7] = {{0.1, 0.3, 0.0},	    /* \  define  */
	{0.3, 0.9, 0.0},  {0.4, 0.4, 0.0}, {0.5, 0.6, 0.0}, /*  \ the	  */
	{0.6, 0.15, 0.0}, {0.8, 0.2, 0.0}, {0.9, 0.6, 0.0}};/*  / control */
    static Pctrl_point3_list CtrlPtList =		    /* /  points  */
	 {PB_SPLINE_NON_RATIONAL, 7, CtrlPts};
    Pcurve_geom_spline	Curve;		/* the spline definition */
    static Ptext_align Alignment = {PHOR_CTR, PVERT_BOTTOM};
    Ppoint 	Loc;			/* position of text string */
    Pint	Error;			/* error-return variable */
    Pint	Quadrant, I, J;		/* loop control variables */

    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);
    pset_char_ht(0.07);
    pset_char_expan(0.7);
    pset_text_align(&Alignment);
    Curve.ctrl_points = CtrlPtList;
    for (Quadrant = 0; Quadrant < 4; Quadrant++) {
	/*--- define the viewing ------------------  four images: +---+---+ */
	Viewport.x_min = (Quadrant % 2) *  0.5;		       /* | 1 | 2 | */
	Viewport.x_max = Viewport.x_min + 0.5;		       /* +---+---+ */
	Viewport.y_min = (Quadrant < 2) * 0.5;		       /* | 3 | 4 | */
	Viewport.y_max = Viewport.y_min + 0.5;		       /* +---+---+ */
	ViewMapping.win = Window;
	ViewMapping.proj_vp = Viewport;
	peval_view_map_matrix(&ViewMapping, &Error, ViewMapMat);
	for (I = 0; I < 3; I++)
	    for (J = 0; J < 3; J++)
		ViewRep.ori_matrix[I][J] = ViewOriMat[I][J],
		ViewRep.map_matrix[I][J] = ViewMapMat[I][J];
	ViewRep.clip_limit = Window;
	ViewRep.xy_clip    = PIND_CLIP;
	pset_view_rep(WorkstnID, Quadrant + 1, &ViewRep);
	pset_view_ind(Quadrant + 1);
	/*--- define the reference curve (linear) --------------------------*/
	Curve.order = Linear;
	MakeKnotVector(Curve.order, 7, KnotVals, &NumKnots, &NumSegs);
	Knots.num_floats = NumKnots;
	Knots.floats = KnotVals;
	Curve.knots = Knots;
	Curve.low_limit = 0.0;
	Curve.high_limit = (float) NumSegs;
	pnon_uniform_b_spline_curve3(&Curve);
	/*--- define the higher-order curve --------------------------------*/
	Curve.order = Linear + Quadrant + 1;
	MakeKnotVector(Curve.order, 7, KnotVals, &NumKnots, &NumSegs);
	Knots.num_floats = NumKnots;
	Knots.floats = KnotVals;
	Curve.knots = Knots;
	Curve.low_limit = 0.0;
	Curve.high_limit = (float) NumSegs;
	pnon_uniform_b_spline_curve3(&Curve);	/* higher-order curve */
	Loc.x = 0.5, Loc.y = 0.03;
	ptext(&Loc, OrderNames[Quadrant]);
    }
    pclose_struct();
    ppost_struct(WorkstnID, TheStructure, 1.0);
    pupd_ws(WorkstnID, PFLAG_PERFORM);
    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 */
}