colourwheel.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" */

#define Sections	60		/* sections to simulate a circle */
#define	dTheta		(360.0/Sections)/* angular width of each piece */
#define	BoldSansSerif	-6		/* text font number */
#define deg 				*3.1415926535897932384/180

main()					/* file "ColourWheel.c" */
{
    Pint		WorkstnID = 1;		/* workstation identifier */
    Pint		ConnID;			/* connection identifier */
    Pint		WorkstnType = POIDDX;	/* out/in, dir, dbl bfr, X */
    Pint		Direct = 0;		/* sent to "pescape_u250" */
    Pint		Structure = 1;		/* structure ID */
    Pvertex3_set	VertexSet;		/* set of vertex lists */
    Pvertex3_list	VertexList;		/* list of vertices w/ data */
    Ppoint3		Vertices[3];		/* do "circle" w/ triangles*/
    Pcolr_rep		Colour, HSVRGB[360];	/* for defining colour map */
    Pcolr_rep		Colours[3];		/* triangle vertex colours */
    static char		Labels[6][8] = {	/* for labelling the wheel */
			"0/6,6/6", "1/6", "2/6", "3/6", "4/6", "5/6"};
    static Ptext_align	CenterHalf = {PHOR_CTR, PVERT_HALF};
    Pmatrix3		xform;			/* for transformations */
    Pvec3		Vec;			/* for translations, etc. */
    Ppoint		Loc;			/* for placing text */
    Pint		Error;			/* error-return variable */
    Pfloat		Theta;			/* loop control variable */
    Pint		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);
    pescape_u250(WorkstnID, Direct);		/* set colour environment */
    /*--- calculate RGB representations of HSV colours ---------------------*/
    for (I = 0, Theta = 0.0; I < Sections; I++, Theta += dTheta) {
	pset_colr_model(WorkstnID, PMODEL_HSV);
	Colour.hsv.hue   = Theta/360.0;		/* \		       */
	Colour.hsv.satur = 1.0;			/*  > fully saturated, */
	Colour.hsv.value = 1.0;			/* /  luminous colour  */
	pset_colr_rep(WorkstnID, 2, &Colour);	/* set HSV colour */
	pset_colr_model(WorkstnID, PCOLR_RGB);
	pinq_colr_rep(WorkstnID, 2,		/* retrieve the colour just */
	  PINQ_REALIZED, &Error, &Colour);	/*   set, but now it's RGB  */
	HSVRGB[I] = Colour;
    }
    /*=== define the color-wheeel structure ================================*/
    popen_struct(Structure);
    pset_int_style(PSTYLE_SOLID);
    pset_int_shad_method(PINT_SHAD_METHOD_COLR);
    /*--- draw the piece-of-pie-shaped segments ----------------------------*/
    Vertices[0].x = Vertices[0].y = Vertices[0].z = 0.0;/* point 1: center */
    Colours[0].rgb.red = Colours[0].rgb.green = Colours[0].rgb.blue = 1.0;
    VertexSet.num_lists = 1;
    VertexSet.vertices = &VertexList;
    VertexList.num_vertices = 3;
    VertexList.num_data_per_vertex = 0;
    VertexList.vertex_points = Vertices;
    VertexList.vertex_colrvs.colr_reps.rgb = (void *) Colours;
    VertexList.vertex_norms = NULL;
    VertexList.vertex_data = NULL;
    for (I = 0, Theta = 0.0; I < Sections; I++, Theta += dTheta) {
	Vertices[1].x = cos((90-Theta) deg);		/* \  point 2:	*/
	Vertices[1].y = sin((90-Theta) deg);		/*  > on the    */
	Vertices[1].z = 0.0;				/* /  perimeter */
	Colours[1] = HSVRGB[I];			/* use pre-calculated colour */
	Vertices[2].x = cos((90-(Theta + dTheta)) deg);	/* \  point 3:  */
	Vertices[2].y = sin((90-(Theta + dTheta)) deg);	/*  > also on   */
	Vertices[2].z = 0.0;				/* /  perimeter */
	if (I < Sections - 1)
	    Colours[2] = HSVRGB[I + 1];		/* next calculated colour */
	else
	    Colours[2] = HSVRGB[0];		/* first calculated colour */
	Vec.delta_x = Vec.delta_y = Vec.delta_z = 0.45;
	pscale3(&Vec, &Error, xform);
	pset_local_tran3(xform, PTYPE_REPLACE);
	Vec.delta_x = Vec.delta_y = Vec.delta_z = 0.5;
	ptranslate3(&Vec, &Error, xform);
	pset_local_tran3(xform, PTYPE_POSTCONCAT);
	pfill_area_set3_data(PCOLR_RGB, NULL, NULL, &VertexSet);
    }
    /*--- do the labels around the perimeter of the wheel ------------------*/
    pset_text_font(BoldSansSerif);
    pset_char_ht(0.05);
    pset_text_align(&CenterHalf);
    for (I = 0; I < 6; I++) {
	Loc.x = 1.08 * cos((90 - I * 60) deg);
	Loc.y = 1.08 * sin((90 - I * 60) deg);
	ptext(&Loc, Labels[I]);
    }
    pclose_struct();
    ppost_struct(WorkstnID, Structure, 1.0);
    pclose_ws(WorkstnID);
    pclose_phigs();
}