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-rw-r--r--src/cmd/pic/arcgen.c221
1 files changed, 221 insertions, 0 deletions
diff --git a/src/cmd/pic/arcgen.c b/src/cmd/pic/arcgen.c
new file mode 100644
index 00000000..d1b64224
--- /dev/null
+++ b/src/cmd/pic/arcgen.c
@@ -0,0 +1,221 @@
+#include <stdio.h>
+#include <math.h>
+#include "pic.h"
+#include "y.tab.h"
+
+void arc_extreme(double, double, double, double, double, double);
+int quadrant(double x, double y);
+
+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, battr;
+ obj *p, *ppos;
+ double fromx, fromy, tox, toy, fillval = 0;
+ Attr *ap;
+
+ prevrad = getfval("arcrad");
+ prevh = getfval("arrowht");
+ prevw = getfval("arrowwid");
+ fromx = curx;
+ fromy = cury;
+ head = to = at = cw = invis = ddtype = battr = 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;
+ case FILL:
+ battr |= FILLBIT;
+ if (ap->a_sub == DEFAULT)
+ fillval = getfval("fillval");
+ else
+ fillval = ap->a_val.f;
+ 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 | battr;
+ p->o_fillval = fillval;
+ 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)
+ /* start, end, center */
+{
+ /* 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);
+}
+
+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 */
+}
+
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