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- #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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