static long gc_common(long iMax, long jMax, double *x, double *y, int *reg, short *triangle, int region, const double *zz, long nchunk, long *nparts)
{
long ntotal= 0;
long n;
gc_site.imax= iMax;
gc_site.jmax= jMax;
gc_site.x= x;
gc_site.y= y;
gc_site.reg= reg;
gc_site.triangle= triangle;
gc_site.z= zz;
gc_site.xcp= gc_site.ycp= 0;
gc_site.n= gc_site.count= 0;
*nparts= 0;
/* get scratch space for data array */
if (GaGetScratchS(gc_site.imax*(gc_site.jmax+1)+1)) return 0;
/* initialize the data array */
data_init(&gc_site, gasScratch, region, nchunk);
/* make first pass to compute required sizes for GcTrace second pass */
for (;;) {
n= curve_tracer(&gc_site, gasScratch, 0);
if (!n) break;
if (n>0) {
(*nparts)++;
ntotal+= n;
} else {
ntotal-= n;
}
}
return ntotal;
}
int GaContourInit(GaQuadMesh *msh, int regn,
const GpReal *zz, GpReal lev)
/* Find the edges cut by the current contour, remembering
z, triangle, and level for the GaContour routine, which
actually walks the contour. The z array represents function
values on the mesh msh. If triangle!=0,
it represents the initial value of the triangulation array,
which determines the behavior of GaContour in saddle zones.
triangle[j][i]= 1, -1, or 0 as the zone bounded by
[j-1][i-1], [j-1][i], [j][i], and [j][i-1]
has been triangulated from (-1,-1) to (0,0),
from (-1,0) to (0,-1), or has not yet been
triangulated.
The msh->triangle array is updated by GaContour.
If a contour passes through an untriangulated saddle zone,
GaContour chooses a triangulation and marks the triangle
array approriately, so that subsequent calls to GaContour
will never produce intersecting contour curves. */
{
long iMax= msh->iMax;
long ijMax= iMax*msh->jMax;
int *ireg= msh->reg;
long ij;
/* Create default region array if none supplied */
if (!ireg) {
ireg= NewReg(iMax, ijMax);
if (!ireg) return 0;
msh->reg= ireg;
}
/* Remember data for GaContour */
mesh= msh;
region= regn;
z= zz;
level= lev;
/* Get scratch space to hold edges */
if (GaGetScratchS(2*ijMax)) return 0;
iedges= gasScratch;
jedges= gasScratch+ijMax;
/* Find all points above contour level */
for (ij=0 ; ij<ijMax ; ij++) iedges[ij]= zz[ij]>lev;
/* Find j=const edges which cut level plane */
nj= njb= 0;
for (ij=1 ; ij<ijMax ; ij++) {
if ((iedges[ij]^iedges[ij-1]) && (EXISTS(ij)||EXISTS(ij+iMax))) {
if ((ireg[ij]==region) ^ (ireg[ij+iMax]==region)) {
jedges[ij]= 2; /* contour enters mesh here */
njb++;
} else {
jedges[ij]= 1; /* interior edge */
nj++;
}
} else {
jedges[ij]= 0;
}
}
jbegin= 1;
/* Find i=const edges which cut level plane */
ni= nib= 0;
for (ij=ijMax-1 ; ij>=iMax ; ij--) {
if ((iedges[ij]^iedges[ij-iMax]) && (EXISTS(ij)||EXISTS(ij+1))) {
if ((ireg[ij]==region) ^ (ireg[ij+1]==region)) {
iedges[ij]= 2; /* contour enters mesh here */
nib++;
} else {
iedges[ij]= 1; /* interior edge */
ni++;
}
} else {
iedges[ij]= 0;
}
}
ibegin= iMax;
/* Set keepLeft to a known value (arbitrary but repeatable) */
keepLeft= 0;
/* Get scratch space for level curves */
if (GaGetScratchP(ni+nib+nj+njb+1)) return 0;
if (tmpReg) FreeTmpReg();
return ni || nib || nj || njb;
}
