plot.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

			ra *= c;
			dec *= c;
			if(dec == 0)
				d1 = c, d2 = c;
			else if(dec < 0)
				d1 = c, d2 = 0;
			else
				d1 = 0, d2 = c;
		}else if(r->type==SAO || r->type==NGC || r->type==Planet || r->type==Abell){
			ra = r->ngc.ra;
			dec = r->ngc.dec;
			d1 = 0, d2 = 0, r0 = 0;
		}else
			continue;
		if(dec+d2+extradec > decmax)
			decmax = dec+d2+extradec;
		if(dec-d1-extradec < decmin)
			decmin = dec-d1-extradec;
		if(folded){
			ra -= 180*c;
			if(ra < 0)
				ra += 360*c;
		}
		if(ra+r0+extrara > ramax)
			ramax = ra+r0+extrara;
		if(ra-extrara < ramin)
			ramin = ra-extrara;
	}

	if(decmax > 90*c)
		decmax = 90*c;
	if(decmin < -90*c)
		decmin = -90*c;
	if(ramin < 0)
		ramin += 360*c;
	if(ramax >= 360*c)
		ramax -= 360*c;

	if(quantize){
		/* quantize to degree boundaries */
		ramin -= ramin%m5;
		if(ramax%m5 != 0)
			ramax += m5-(ramax%m5);
		if(decmin > 0)
			decmin -= decmin%c;
		else
			decmin -= c - (-decmin)%c;
		if(decmax > 0){
			if(decmax%c != 0)
				decmax += c-(decmax%c);
		}else if(decmax < 0){
			if(decmax%c != 0)
				decmax += ((-decmax)%c);
		}
	}

	if(folded){
		if(ramax-ramin > 270*c){
			fprint(2, "ra range too wide %ld°\n", (ramax-ramin)/c);
			return -1;
		}
	}else if(ramax-ramin > 270*c){
		folded = 1;
		return bbox(0, 0, quantize);
	}

	return 1;
}

int
inbbox(DAngle ra, DAngle dec)
{
	int min;

	if(dec < decmin)
		return 0;
	if(dec > decmax)
		return 0;
	min = ramin;
	if(ramin > ramax){	/* straddling 0h0m */
		min -= 360*c;
		if(ra > 180*c)
			ra -= 360*c;
	}
	if(ra < min)
		return 0;
	if(ra > ramax)
		return 0;
	return 1;
}

int
gridra(long mapdec)
{
	mapdec = abs(mapdec)+c/2;
	mapdec /= c;
	if(mapdec < 60)
		return m5;
	if(mapdec < 80)
		return 2*m5;
	if(mapdec < 85)
		return 4*m5;
	return 8*m5;
}

#define	GREY	(nogrey? display->white : grey)

void
plot(char *flags)
{
	int i, j, k;
	char *t;
	long x, y;
	int ra, dec;
	int m;
	Point p, pts[10];
	Record *r;
	Rectangle rect, r1;
	int dx, dy, nogrid, textlevel, nogrey, zenithup;
	Image *scr;
	char *name, buf[32];
	double v;

	if(plotopen() < 0)
		return;
	nogrid = 0;
	nogrey = 0;
	textlevel = 1;
	dx = 512;
	dy = 512;
	zenithup = 0;
	for(;;){
		if(t = alpha(flags, "nogrid")){
			nogrid = 1;
			flags = t;
			continue;
		}
		if((t = alpha(flags, "zenith")) || (t = alpha(flags, "zenithup")) ){
			zenithup = 1;
			flags = t;
			continue;
		}
		if((t = alpha(flags, "notext")) || (t = alpha(flags, "nolabel")) ){
			textlevel = 0;
			flags = t;
			continue;
		}
		if((t = alpha(flags, "alltext")) || (t = alpha(flags, "alllabel")) ){
			textlevel = 2;
			flags = t;
			continue;
		}
		if(t = alpha(flags, "dx")){
			dx = strtol(t, &t, 0);
			if(dx < 100){
				fprint(2, "dx %d too small (min 100) in plot\n", dx);
				return;
			}
			flags = skipbl(t);
			continue;
		}
		if(t = alpha(flags, "dy")){
			dy = strtol(t, &t, 0);
			if(dy < 100){
				fprint(2, "dy %d too small (min 100) in plot\n", dy);
				return;
			}
			flags = skipbl(t);
			continue;
		}
		if((t = alpha(flags, "nogrey")) || (t = alpha(flags, "nogray"))){
			nogrey = 1;
			flags = skipbl(t);
			continue;
		}
		if(*flags){
			fprint(2, "syntax error in plot\n");
			return;
		}
		break;
	}
	flatten();
	folded = 0;

	if(bbox(0, 0, 1) < 0)
		return;
	if(ramax-ramin<100 || decmax-decmin<100){
		fprint(2, "plot too small\n");
		return;
	}

	scr = allocimage(display, Rect(0, 0, dx, dy), RGB24, 0, DBlack);
	if(scr == nil){
		fprint(2, "can't allocate image: %r\n");
		return;
	}
	rect = scr->r;
	rect.min.x += 16;
	rect = insetrect(rect, 40);
	if(setmap(ramin, ramax, decmin, decmax, rect, zenithup) < 0){
		fprint(2, "can't set up map coordinates\n");
		return;
	}
	if(!nogrid){
		for(x=ramin; ; ){
			for(j=0; j<nelem(pts); j++){
				/* use double to avoid overflow */
				v = (double)j / (double)(nelem(pts)-1);
				v = decmin + v*(decmax-decmin);
				pts[j] = map(x, v);
			}
			bezspline(scr, pts, nelem(pts), Endsquare, Endsquare, 0, GREY, ZP);
			ra = x;
			if(folded){
				ra -= 180*c;
				if(ra < 0)
					ra += 360*c;
			}
			p = pts[0];
			p.x -= stringwidth(font, hm5(angle(ra)))/2;
			string(scr, p, GREY, ZP, font, hm5(angle(ra)));
			p = pts[nelem(pts)-1];
			p.x -= stringwidth(font, hm5(angle(ra)))/2;
			p.y -= font->height;
			string(scr, p, GREY, ZP, font, hm5(angle(ra)));
			if(x == ramax)
				break;
			x += gridra(mapdec);
			if(x > ramax)
				x = ramax;
		}
		for(y=decmin; y<=decmax; y+=c){
			for(j=0; j<nelem(pts); j++){
				/* use double to avoid overflow */
				v = (double)j / (double)(nelem(pts)-1);
				v = ramin + v*(ramax-ramin);
				pts[j] = map(v, y);
			}
			bezspline(scr, pts, nelem(pts), Endsquare, Endsquare, 0, GREY, ZP);
			p = pts[0];
			p.x += 3;
			p.y -= font->height/2;
			string(scr, p, GREY, ZP, font, deg(angle(y)));
			p = pts[nelem(pts)-1];
			p.x -= 3+stringwidth(font, deg(angle(y)));
			p.y -= font->height/2;
			string(scr, p, GREY, ZP, font, deg(angle(y)));
		}
	}
	/* reorder to get planets in front of stars */
	tolast(nil);
	tolast("moon");		/* moon is in front of everything... */
	tolast("shadow");	/* ... except the shadow */

	for(i=0,r=rec; i<nrec; i++,r++){
		dec = r->ngc.dec;
		ra = r->ngc.ra;
		if(folded){
			ra -= 180*c;
			if(ra < 0)
				ra += 360*c;
		}
		if(textlevel){
			name = nameof(r);
			if(name==nil && textlevel>1 && r->type==SAO){
				snprint(buf, sizeof buf, "SAO%ld", r->index);
				name = buf;
			}
			if(name)
				drawname(scr, nogrey? display->white : alphagrey, name, ra, dec);
		}
		if(r->type == Planet){
			drawplanet(scr, &r->planet, map(ra, dec));
			continue;
		}
		if(r->type == SAO){
			m = r->sao.mag;
			if(m == UNKNOWNMAG)
				m = r->sao.mpg;
			if(m == UNKNOWNMAG)
				continue;
			m = dsize(m);
			if(m < 3)
				fillellipse(scr, map(ra, dec), m, m, nogrey? display->white : lightgrey, ZP);
			else{
				ellipse(scr, map(ra, dec), m+1, m+1, 0, display->black, ZP);
				fillellipse(scr, map(ra, dec), m, m, display->white, ZP);
			}
			continue;
		}
		if(r->type == Abell){
			ellipse(scr, addpt(map(ra, dec), Pt(-3, 2)), 2, 1, 0, lightblue, ZP);
			ellipse(scr, addpt(map(ra, dec), Pt(3, 2)), 2, 1, 0, lightblue, ZP);
			ellipse(scr, addpt(map(ra, dec), Pt(0, -2)), 1, 2, 0, lightblue, ZP);
			continue;
		}
		switch(r->ngc.type){
		case Galaxy:
			j = npixels(r->ngc.diam);
			if(j < 4)
				j = 4;
			if(j > 10)
				k = j/3;
			else
				k = j/2;
			ellipse(scr, map(ra, dec), j, k, 0, lightblue, ZP);
			break;

		case PlanetaryN:
			p = map(ra, dec);
			j = npixels(r->ngc.diam);
			if(j < 3)
				j = 3;
			ellipse(scr, p, j, j, 0, green, ZP);
			line(scr, Pt(p.x, p.y+j+1), Pt(p.x, p.y+j+4),
				Endsquare, Endsquare, 0, green, ZP);
			line(scr, Pt(p.x, p.y-(j+1)), Pt(p.x, p.y-(j+4)),
				Endsquare, Endsquare, 0, green, ZP);
			line(scr, Pt(p.x+j+1, p.y), Pt(p.x+j+4, p.y),
				Endsquare, Endsquare, 0, green, ZP);
			line(scr, Pt(p.x-(j+1), p.y), Pt(p.x-(j+4), p.y),
				Endsquare, Endsquare, 0, green, ZP);
			break;

		case DiffuseN:
		case NebularCl:
			p = map(ra, dec);
			j = npixels(r->ngc.diam);
			if(j < 4)
				j = 4;
			r1.min = Pt(p.x-j, p.y-j);
			r1.max = Pt(p.x+j, p.y+j);
			if(r->ngc.type != DiffuseN)
				draw(scr, r1, ocstipple, ocstipple, ZP);
			line(scr, Pt(p.x-j, p.y-j), Pt(p.x+j, p.y-j),
				Endsquare, Endsquare, 0, green, ZP);
			line(scr, Pt(p.x-j, p.y+j), Pt(p.x+j, p.y+j),
				Endsquare, Endsquare, 0, green, ZP);
			line(scr, Pt(p.x-j, p.y-j), Pt(p.x-j, p.y+j),
				Endsquare, Endsquare, 0, green, ZP);
			line(scr, Pt(p.x+j, p.y-j), Pt(p.x+j, p.y+j),
				Endsquare, Endsquare, 0, green, ZP);
			break;

		case OpenCl:
			p = map(ra, dec);
			j = npixels(r->ngc.diam);
			if(j < 4)
				j = 4;
			fillellipse(scr, p, j, j, ocstipple, ZP);
			break;

		case GlobularCl:
			j = npixels(r->ngc.diam);
			if(j < 4)
				j = 4;
			p = map(ra, dec);
			ellipse(scr, p, j, j, 0, lightgrey, ZP);
			line(scr, Pt(p.x-(j-1), p.y), Pt(p.x+j, p.y),
				Endsquare, Endsquare, 0, lightgrey, ZP);
			line(scr, Pt(p.x, p.y-(j-1)), Pt(p.x, p.y+j),
				Endsquare, Endsquare, 0, lightgrey, ZP);
			break;

		}
	}
	flushimage(display, 1);
	displayimage(scr);
}

int
runcommand(char *command, int p[2])
{
	switch(rfork(RFPROC|RFFDG|RFNOWAIT)){
	case -1:
		return -1;
	default:
		break;
	case 0:
		dup(p[1], 1);
		close(p[0]);
		close(p[1]);
		execl("/bin/rc", "rc", "-c", command, nil);
		fprint(2, "can't exec %s: %r", command);
		exits(nil);
	}
	return 1;
}

void
parseplanet(char *line, Planetrec *p)
{
	char *fld[6];
	int i, nfld;
	char *s;

	if(line[0] == '\0')
		return;
	line[10] = '\0';	/* terminate name */
	s = strrchr(line, ' ');
	if(s == nil)
		s = line;
	else
		s++;
	strcpy(p->name, s);
	for(i=0; s[i]!='\0'; i++)
		p->name[i] = tolower(s[i]);
	p->name[i] = '\0';
	nfld = getfields(line+11, fld, nelem(fld), 1, " ");
	p->ra = dangle(getra(fld[0]));
	p->dec = dangle(getra(fld[1]));
	p->az = atof(fld[2])*MILLIARCSEC;
	p->alt = atof(fld[3])*MILLIARCSEC;
	p->semidiam = atof(fld[4])*1000;
	if(nfld > 5)
		p->phase = atof(fld[5]);
	else
		p->phase = 0;
}

void
astro(char *flags, int initial)
{
	int p[2];
	int i, n, np;
	char cmd[256], buf[4096], *lines[20], *fld[10];

	snprint(cmd, sizeof cmd, "/bin/astro -p %s", flags);
	if(pipe(p) < 0){
		fprint(2, "can't pipe: %r\n");
		return;
	}
	if(runcommand(cmd, p) < 0){
		close(p[0]);
		close(p[1]);
		fprint(2, "can't run astro: %r");
		return;
	}
	close(p[1]);
	n = readn(p[0], buf, sizeof buf-1);
	if(n <= 0){
		fprint(2, "no data from astro\n");
		return;
	}
	if(!initial)
		Bwrite(&bout, buf, n);
	buf[n] = '\0';
	np = getfields(buf, lines, nelem(lines), 0, "\n");
	if(np <= 1){
		fprint(2, "astro: not enough output\n");
		return;
	}
	Bprint(&bout, "%s\n", lines[0]);
	Bflush(&bout);
	/* get latitude and longitude */
	if(getfields(lines[0], fld, nelem(fld), 1, " ") < 8)
		fprint(2, "astro: can't read longitude: too few fields\n");
	else{
		mysid = getra(fld[5])*180./PI;
		mylat = getra(fld[6])*180./PI;
		mylon = getra(fld[7])*180./PI;
	}
	/*
	 * Each time we run astro, we generate a new planet list
	 * so multiple appearances of a planet may exist as we plot
	 * its motion over time.
	 */
	planet = malloc(NPlanet*sizeof planet[0]);
	if(planet == nil){
		fprint(2, "astro: malloc failed: %r\n");
		exits("malloc");
	}
	memset(planet, 0, NPlanet*sizeof planet[0]);
	for(i=1; i<np; i++)
		parseplanet(lines[i], &planet[i-1]);
}