static void
pldrawcn(PLFLT (*f2eval) (PLINT, PLINT, PLPointer),
PLPointer f2eval_data,
PLINT nx, PLINT ny, PLINT kx, PLINT lx,
PLINT ky, PLINT ly, PLFLT flev, char *flabel, PLINT kcol, PLINT krow,
PLFLT lastx, PLFLT lasty, PLINT startedge, PLINT **ipts,
PLFLT *distance, PLINT *lastindex,
void (*pltr) (PLFLT, PLFLT, PLFLT *, PLFLT *, PLPointer),
PLPointer pltr_data)
{
PLFLT f[4];
PLFLT px[4], py[4], locx[4], locy[4];
PLINT iedge[4];
PLINT i, j, k, num, first, inext, kcolnext, krownext;
(*pltr) (kcol,krow+1,&px[0],&py[0],pltr_data);
(*pltr) (kcol,krow,&px[1],&py[1],pltr_data);
(*pltr) (kcol+1,krow,&px[2],&py[2],pltr_data);
(*pltr) (kcol+1,krow+1,&px[3],&py[3],pltr_data);
f[0] = f2eval(kcol, krow+1, f2eval_data)-flev;
f[1] = f2eval(kcol, krow, f2eval_data)-flev;
f[2] = f2eval(kcol+1, krow, f2eval_data)-flev;
f[3] = f2eval(kcol+1, krow+1, f2eval_data)-flev;
for (i=0,j=1;i<4;i++,j = (j+1)%4) {
iedge[i] = (f[i]*f[j]>0.0)?-1:((f[i]*f[j] < 0.0)?1:0);
}
/* Mark this square as done */
ipts[kcol][krow] = 1;
/* Check if no contour has been crossed i.e. iedge[i] = -1 */
if ((iedge[0] == -1) && (iedge[1] == -1) && (iedge[2] == -1)
&& (iedge[3] == -1)) return;
/* Check if this is a completely flat square - in which case
ignore it */
if ( (f[0] == 0.0) && (f[1] == 0.0) && (f[2] == 0.0) &&
(f[3] == 0.0) ) return;
/* Calculate intersection points */
num = 0;
if (startedge < 0) {
first = 1;
}
else {
locx[num] = lastx;
locy[num] = lasty;
num++;
first = 0;
}
for (k=0, i = (startedge<0?0:startedge);k<4;k++,i=(i+1)%4) {
if (i == startedge) continue;
/* If the contour is an edge check it hasn't already been done */
if (f[i] == 0.0 && f[(i+1)%4] == 0.0) {
kcolnext = kcol;
krownext = krow;
if (i == 0) kcolnext--;
if (i == 1) krownext--;
if (i == 2) kcolnext++;
if (i == 3) krownext++;
if ((kcolnext < kx) || (kcolnext >= lx) ||
(krownext < ky) || (krownext >= ly) ||
(ipts[kcolnext][krownext] == 1)) continue;
}
if ((iedge[i] == 1) || (f[i] == 0.0)) {
j = (i+1)%4;
if (f[i] != 0.0) {
locx[num] = (px[i]*fabs(f[j])+px[j]*fabs(f[i]))/fabs(f[j]-f[i]);
locy[num] = (py[i]*fabs(f[j])+py[j]*fabs(f[i]))/fabs(f[j]-f[i]);
}
else {
locx[num] = px[i];
locy[num] = py[i];
}
/* If this is the start of the contour then move to the point */
if (first == 1) {
cont_mv_store(locx[num],locy[num]);
first = 0;
*distance = 0;
*lastindex = 0;
}
else {
/* Link to the next point on the contour */
if (contlabel_active)
pl_drawcontlabel(locx[num], locy[num], flabel, distance, lastindex);
else
cont_xy_store(locx[num],locy[num]);
/* Need to follow contour into next grid box */
/* Easy case where contour does not pass through corner */
if (f[i] != 0.0) {
kcolnext = kcol;
krownext = krow;
inext = (i+2)%4;
if (i == 0) kcolnext--;
if (i == 1) krownext--;
if (i == 2) kcolnext++;
if (i == 3) krownext++;
if ((kcolnext >= kx) && (kcolnext < lx) &&
(krownext >= ky) && (krownext < ly) &&
(ipts[kcolnext][krownext] == 0)) {
pldrawcn(f2eval, f2eval_data,
nx, ny, kx, lx, ky, ly, flev, flabel,
kcolnext, krownext,
locx[num], locy[num], inext, ipts,
distance, lastindex,
pltr, pltr_data);
}
}
/* Hard case where contour passes through corner */
/* This is still not perfect - it may lose the contour
* which won't upset the contour itself (we can find it
* again later) but might upset the labelling */
else {
kcolnext = kcol;
krownext = krow;
inext = (i+2)%4;
if (i == 0) {kcolnext--; krownext++;}
if (i == 1) {krownext--; kcolnext--;}
if (i == 2) {kcolnext++; krownext--;}
if (i == 3) {krownext++; kcolnext++;}
if ((kcolnext >= kx) && (kcolnext < lx) &&
(krownext >= ky) && (krownext < ly) &&
(ipts[kcolnext][krownext] == 0)) {
pldrawcn(f2eval, f2eval_data,
nx, ny, kx, lx, ky, ly, flev, flabel,
kcolnext, krownext,
locx[num], locy[num], inext, ipts,
distance, lastindex,
pltr, pltr_data);
}
}
if (first == 1) {
/* Move back to first point */
cont_mv_store(locx[num],locy[num]);
first = 0;
*distance = 0;
*lastindex = 0;
first = 0;
}
else {
first = 1;
}
num++;
}
}
}
}
static void
pldrawcn(PLFLT (*f2eval) (PLINT, PLINT, PLPointer),
PLPointer f2eval_data,
PLINT nx, PLINT ny, PLINT kx, PLINT lx,
PLINT ky, PLINT ly, PLFLT flev, char *flabel, PLINT kcol, PLINT krow,
PLINT *p_kscan, PLINT *p_kstor, PLINT *iscan,
PLINT *ixstor, PLINT *iystor, PLINT nstor,
void (*pltr) (PLFLT, PLFLT, PLFLT *, PLFLT *, PLPointer),
PLPointer pltr_data)
{
PLINT iwbeg, ixbeg, iybeg, izbeg;
PLINT iboun, iw, ix, iy, iz, ifirst, istep, ixgo, iygo;
PLINT l, ixg, iyg, ia, ib;
PLFLT dist, dx, dy, xnew, ynew, fxl, fxr;
PLFLT xlas = 0., ylas = 0., tpx, tpy, xt, yt;
PLFLT f1, f2, f3, f4, fcheck;
PLINT lastindex = 0;
PLFLT distance = 0.0;
/* Check if a contour has been crossed */
fxl = f2eval(kcol-1, krow, f2eval_data);
fxr = f2eval(kcol, krow, f2eval_data);
if (fxl < flev && fxr >= flev) {
ixbeg = kcol - 1;
iwbeg = kcol;
}
else if (fxr < flev && fxl > flev) {
ixbeg = kcol;
iwbeg = kcol - 1;
}
else
return;
iybeg = krow;
izbeg = krow;
/* A contour has been crossed. */
/* Check to see if it is a new one. */
for (l = 0; l < *p_kscan; l++) {
if (ixbeg == iscan[l])
return;
}
for (iboun = 1; iboun >= -1; iboun -= 2) {
/* Set up starting point and initial search directions */
ix = ixbeg;
iy = iybeg;
iw = iwbeg;
iz = izbeg;
ifirst = 1;
istep = 0;
ixgo = iw - ix;
iygo = iz - iy;
for (;;) {
plccal(f2eval, f2eval_data,
flev, ix, iy, ixgo, iygo, &dist);
dx = dist * ixgo;
dy = dist * iygo;
xnew = ix + dx;
ynew = iy + dy;
/* Has a step occured in search? */
if (istep != 0) {
if (ixgo * iygo == 0) {
/* This was a diagonal step, so interpolate missed point. */
/* Rotating 45 degrees to get it */
ixg = ixgo;
iyg = iygo;
plr45(&ixg, &iyg, iboun);
ia = iw - ixg;
ib = iz - iyg;
plccal(f2eval, f2eval_data,
flev, ia, ib, ixg, iyg, &dist);
(*pltr) (xlas, ylas, &tpx, &tpy, pltr_data);
if (contlabel_active)
pl_drawcontlabel(tpx, tpy, flabel, &distance, &lastindex);
else
cont_xy_store(tpx,tpy); /* plP_drawor(tpx, tpy); */
dx = dist * ixg;
dy = dist * iyg;
xlas = ia + dx;
ylas = ib + dy;
}
else {
if (dist > 0.5) {
xt = xlas;
xlas = xnew;
xnew = xt;
yt = ylas;
ylas = ynew;
ynew = yt;
}
}
}
if (ifirst != 1) {
(*pltr) (xlas, ylas, &tpx, &tpy, pltr_data);
if (contlabel_active)
pl_drawcontlabel(tpx, tpy, flabel, &distance, &lastindex);
else
cont_xy_store(tpx,tpy); /* plP_drawor(tpx, tpy); */
}
else {
(*pltr) (xnew, ynew, &tpx, &tpy, pltr_data);
cont_mv_store(tpx,tpy); /* plP_movwor(tpx, tpy); */
}
xlas = xnew;
ylas = ynew;
/* Check if the contour is closed */
if (ifirst != 1 &&
ix == ixbeg && iy == iybeg && iw == iwbeg && iz == izbeg) {
(*pltr) (xlas, ylas, &tpx, &tpy, pltr_data);
if (contlabel_active)
pl_drawcontlabel(tpx, tpy, flabel, &distance, &lastindex);
else
cont_xy_store(tpx,tpy); /* plP_drawor(tpx, tpy); */
return;
}
ifirst = 0;
/* Now the rotation */
istep = 0;
plr45(&ixgo, &iygo, iboun);
iw = ix + ixgo;
iz = iy + iygo;
/* Check if out of bounds */
if (iw < kx || iw > lx || iz < ky || iz > ly)
break;
/* Has contact been lost with the contour? */
if (ixgo * iygo == 0)
fcheck = f2eval(iw, iz, f2eval_data);
else {
f1 = f2eval(ix, iy, f2eval_data);
f2 = f2eval(iw, iz, f2eval_data);
f3 = f2eval(ix, iz, f2eval_data);
f4 = f2eval(iw, iy, f2eval_data);
fcheck = MAX(f2, (f1 + f2 + f3 + f4) / 4.);
}
if (fcheck < flev) {
/* Yes, lost contact => step to new center */
istep = 1;
ix = iw;
iy = iz;
plr135(&ixgo, &iygo, iboun);
iw = ix + ixgo;
iz = iy + iygo;
/* And do the contour memory */
if (iy == krow) {
*p_kscan = *p_kscan + 1;
iscan[*p_kscan - 1] = ix;
}
else if (iy > krow) {
*p_kstor = *p_kstor + 1;
if (*p_kstor > nstor) {
plabort("plfcont: heap exhausted");
error = 1;
return;
}
ixstor[*p_kstor - 1] = ix;
iystor[*p_kstor - 1] = iy;
}
}
}
/* Reach here only if boundary encountered - Draw last bit */
(*pltr) (xnew, ynew, &tpx, &tpy, pltr_data);
/* distance = 0.0; */
cont_xy_store(tpx,tpy); /* plP_drawor(tpx, tpy); */
}
}
