aboutsummaryrefslogtreecommitdiff
path: root/src/cmd/tpic/arcgen.c
blob: de43dcd23a95af78672813106b8db4276b96527e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
#include	<stdio.h>
#include	<math.h>
#include	"pic.h"
#include	"y.tab.h"

obj*
arcgen(int type)	/* handles circular and (eventually) elliptical arcs */
{
	static double prevw = HT10;
	static double prevh = HT5;
	static double prevrad = HT2;
	static int dtox[2][4] ={ 1, -1, -1, 1, 1, 1, -1, -1 };
	static int dtoy[2][4] ={ 1, 1, -1, -1, -1, 1, 1, -1 };
	static int dctrx[2][4] ={ 0, -1, 0, 1, 0, 1, 0, -1 };
	static int dctry[2][4] ={ 1, 0, -1, 0, -1, 0, 1, 0 };
	static int nexthv[2][4] ={ U_DIR, L_DIR, D_DIR, R_DIR, D_DIR, R_DIR, U_DIR, L_DIR };
	double dx2, dy2, ht, phi, r, d;
	int i, head, to, at, cw, invis, ddtype;
	obj *p, *ppos;
	double fromx, fromy, tox, toy;
	Attr *ap;

	tox = 0;
	toy = 0;
	prevrad = getfval("arcrad");
	prevh = getfval("arrowht");
	prevw = getfval("arrowwid");
	fromx = curx;
	fromy = cury;
	head = to = at = cw = invis = ddtype = 0;
	for (i = 0; i < nattr; i++) {
		ap = &attr[i];
		switch (ap->a_type) {
		case TEXTATTR:
			savetext(ap->a_sub, ap->a_val.p);
			break;
		case HEAD:
			head += ap->a_val.i;
			break;
		case INVIS:
			invis = INVIS;
			break;
		case HEIGHT:	/* length of arrowhead */
			prevh = ap->a_val.f;
			break;
		case WIDTH:	/* width of arrowhead */
			prevw = ap->a_val.f;
			break;
		case RADIUS:
			prevrad = ap->a_val.f;
			break;
		case DIAMETER:
			prevrad = ap->a_val.f / 2;
			break;
		case CW:
			cw = 1;
			break;
		case FROM:	/* start point of arc */
			ppos = ap->a_val.o;
			fromx = ppos->o_x;
			fromy = ppos->o_y;
			break;
		case TO:	/* end point of arc */
			ppos = ap->a_val.o;
			tox = ppos->o_x;
			toy = ppos->o_y;
			to++;
			break;
		case AT:	/* center of arc */
			ppos = ap->a_val.o;
			curx = ppos->o_x;
			cury = ppos->o_y;
			at = 1;
			break;
		case UP:
			hvmode = U_DIR;
			break;
		case DOWN:
			hvmode = D_DIR;
			break;
		case RIGHT:
			hvmode = R_DIR;
			break;
		case LEFT:
			hvmode = L_DIR;
			break;
		}
	}
	if (!at && !to) {	/* the defaults are mostly OK */
		curx = fromx + prevrad * dctrx[cw][hvmode];
		cury = fromy + prevrad * dctry[cw][hvmode];
		tox = fromx + prevrad * dtox[cw][hvmode];
		toy = fromy + prevrad * dtoy[cw][hvmode];
		hvmode = nexthv[cw][hvmode];
	}
	else if (!at) {
		dx2 = (tox - fromx) / 2;
		dy2 = (toy - fromy) / 2;
		phi = atan2(dy2, dx2) + (cw ? -PI/2 : PI/2);
		if (prevrad <= 0.0)
			prevrad = dx2*dx2+dy2*dy2;
		for (r=prevrad; (d = r*r - (dx2*dx2+dy2*dy2)) <= 0.0; r *= 2)
			;	/* this kludge gets around too-small radii */
		prevrad = r;
		ht = sqrt(d);
		curx = fromx + dx2 + ht * cos(phi);
		cury = fromy + dy2 + ht * sin(phi);
		dprintf("dx2,dy2=%g,%g, phi=%g, r,ht=%g,%g\n",
			dx2, dy2, phi, r, ht);
	}
	else if (at && !to) {	/* do we have all the cases??? */
		tox = fromx + prevrad * dtox[cw][hvmode];
		toy = fromy + prevrad * dtoy[cw][hvmode];
		hvmode = nexthv[cw][hvmode];
	}
	if (cw) {	/* interchange roles of from-to and heads */
		double temp;
		temp = fromx; fromx = tox; tox = temp;
		temp = fromy; fromy = toy; toy = temp;
		if (head == HEAD1)
			head = HEAD2;
		else if (head == HEAD2)
			head = HEAD1;
	}
	p = makenode(type, 7);
	arc_extreme(fromx, fromy, tox, toy, curx, cury);
	p->o_val[0] = fromx;
	p->o_val[1] = fromy;
	p->o_val[2] = tox;
	p->o_val[3] = toy;
	if (cw) {
		curx = fromx;
		cury = fromy;
	} else {
		curx = tox;
		cury = toy;
	}
	p->o_val[4] = prevw;
	p->o_val[5] = prevh;
	p->o_val[6] = prevrad;
	p->o_attr = head | (cw ? CW_ARC : 0) | invis | ddtype;
	if (head)
		p->o_nhead = getfval("arrowhead");
	dprintf("arc rad %g at %g %g from %g %g to %g %g head %g %g\n",
		prevrad, p->o_x, p->o_y,
		p->o_val[0], p->o_val[1], p->o_val[2], p->o_val[3], p->o_val[4], p->o_val[5]);
	return(p);
}

/***************************************************************************
   bounding box of a circular arc             Eric Grosse  24 May 84

Conceptually, this routine generates a list consisting of the start,
end, and whichever north, east, south, and west points lie on the arc.
The bounding box is then the range of this list.
    list = {start,end}
    j = quadrant(start)
    k = quadrant(end)
    if( j==k && long way 'round )  append north,west,south,east
    else
      while( j != k )
         append center+radius*[j-th of north,west,south,east unit vectors]
         j += 1  (mod 4)
    return( bounding box of list )
The following code implements this, with simple optimizations.
***********************************************************************/


void
arc_extreme(double x0, double y0, double x1, double y1, double xc, double yc)
{
	/* assumes center isn't too far out */
	double r, xmin, ymin, xmax, ymax;
	int j, k;
	x0 -= xc; y0 -= yc;	/* move to center */
	x1 -= xc; y1 -= yc;
	xmin = (x0<x1)?x0:x1; ymin = (y0<y1)?y0:y1;
	xmax = (x0>x1)?x0:x1; ymax = (y0>y1)?y0:y1;
	r = sqrt(x0*x0 + y0*y0);
	if (r > 0.0) {
		j = quadrant(x0,y0);
		k = quadrant(x1,y1);
		if (j == k && y1*x0 < x1*y0) {
			/* viewed as complex numbers, if Im(z1/z0)<0, arc is big */
			if( xmin > -r) xmin = -r; if( ymin > -r) ymin = -r;
			if( xmax <  r) xmax =  r; if( ymax <  r) ymax =  r;
		} else {
			while (j != k) {
				switch (j) {
					case 1: if( ymax <  r) ymax =  r; break; /* north */
					case 2: if( xmin > -r) xmin = -r; break; /* west */
					case 3: if( ymin > -r) ymin = -r; break; /* south */
					case 4: if( xmax <  r) xmax =  r; break; /* east */
				}
				j = j%4 + 1;
			}
		}
	}
	xmin += xc; ymin += yc;
	xmax += xc; ymax += yc;
	extreme(xmin, ymin);
	extreme(xmax, ymax);
}

int
quadrant(double x, double y)
{
	if (     x>=0.0 && y> 0.0) return(1);
	else if( x< 0.0 && y>=0.0) return(2);
	else if( x<=0.0 && y< 0.0) return(3);
	else if( x> 0.0 && y<=0.0) return(4);
	else			   return 0;	/* shut up lint */
}