char *sdoc ="GRID2HG - 3D grid to horizons grid conversion \n""\n""grid2hg <infile [required parameters]\n""\n""Required Parameters:\n""infile=        name of the input 3D grid file	(velocity)	\n""gridval=       grid value to define where the 3D body is				\n""top=           name of the 2D depth grid defining the top of the 3D body \n""ovtop=         name of the 2D depth grid defining the overhang top \n""ovbot=         name of the 2D depth grid defining the overhang bottom \n""bottom=        name of the 2D depth grid defining the bottom of the 3D body\n""nullval=       null value to define absence of the 3D body	\n""Optional Parameters:\n""tol=0.01       tolerance value where |gridval-grid|<tol is within the 3D \n""               body \n""\n""AUTHOR:  Zhiming Li,         9/5/96			\n""\n";#include "usgrid.h"#include "par.h"int main(int argc, char **argv){	usghed ugh;	FILE *infp,*topfp,*botfp,*ovtfp,*ovbfp;	char *infile,*top,*bottom,*ovtop,*ovbot;	float *ztop, *zbot, *zovt, *zovb, *grid;	float gridval, nullval, tol;	int ierr;	int itop, iovt, iovb, ibot;	int n1,n2,n3;	int i1,i2,i3;	float d1,d2,d3;	float o1,o2,o3;	float gmin, gmax;	/* hook up getpar */	initargs(argc,argv);	askdoc(0);	/* get parameters */	if(getparstring("infile",&infile)) {		infp = efopen(infile,"r");	} else {		infp = stdin;	}	ierr = fgetusghdr(infp,&ugh);    if(ierr!=0) err(" input grid header error ");	if(getparstring("top",&top)) {		topfp = efopen(top,"w");	} else {		err(" top file missing");	}	if(getparstring("ovtop",&ovtop)) {		ovtfp = efopen(ovtop,"w");	} else {		err(" overhang top file missing");	}	if(getparstring("ovbot",&ovbot)) {		ovbfp = efopen(ovbot,"w");	} else {		err(" overhang bottom file missing");	}	if(getparstring("bottom",&bottom)) {		botfp = efopen(bottom,"w");	} else {		err(" bottom file missing");	}	if(!getparfloat("gridval",&gridval)) err(" gridval missing");	if(!getparfloat("nullval",&nullval)) err(" nullval missing");	if(!getparfloat("tol",&tol)) tol = 0.01;	n1 = ugh.n1;	n2 = ugh.n2;	n3 = ugh.n3;	o1 = ugh.o1;	o2 = ugh.o2;	o3 = ugh.o3;	d1 = ugh.d1;	d2 = ugh.d2;	d3 = ugh.d3;	/* memory allocations */	ztop = (float*) emalloc(n2*n3*sizeof(float));	zbot = (float*) emalloc(n2*n3*sizeof(float));	zovb = (float*) emalloc(n2*n3*sizeof(float));	zovt = (float*) emalloc(n2*n3*sizeof(float));	grid = (float*) emalloc(n1*sizeof(float));		for(i3=0;i3<n3;i3++) {		for(i2=0;i2<n2;i2++) {			efread(grid,sizeof(float),n1,infp);			itop = -1;			iovt = -1;			iovb = -1;			ibot = -1;			ztop[i2+i3*n2] = nullval;			zovt[i2+i3*n2] = nullval;			zovb[i2+i3*n2] = nullval;			zbot[i2+i3*n2] = nullval;			for(i1=0;i1<n1;i1++) {				if(fabs(grid[i1]-gridval)<tol) {					itop = i1;					break;				}			}			for(i1=itop+1;i1<n1;i1++) {				if(fabs(grid[i1-1]-gridval)<tol &&				   fabs(grid[i1]-gridval)>tol) {				   iovt = i1-1;				   break;				}			}			for(i1=iovt+1;i1<n1;i1++) {				if(fabs(grid[i1-1]-gridval)>tol &&				   fabs(grid[i1]-gridval)<tol) {				   iovb = i1;				   break;				}			}			for(i1=iovb+1;i1<n1;i1++) {				if(fabs(grid[i1-1]-gridval)<tol &&				   fabs(grid[i1]-gridval)>tol) {				   ibot = i1-1;				   break;				}			}			if(fabs(grid[n1-1]-gridval)<tol) ibot=n1-1;			if(itop>=0 && iovt>=0 && iovb<0 && ibot<0)  {				ibot = iovt;				iovt = -1;			}		    if(itop>=0) ztop[i2+i3*n2] = o1+itop*d1;		    if(iovt>=0) zovt[i2+i3*n2] = o1+iovt*d1;		    if(iovb>=0) zovb[i2+i3*n2] = o1+iovb*d1;		    if(ibot>=0) zbot[i2+i3*n2] = o1+ibot*d1;		}	}	ugh.o1 = o2;	ugh.o2 = o3;	ugh.d1 = d2;	ugh.d2 = d3;	ugh.n1 = n2;	ugh.n2 = n3;	ugh.o3 = 0.;	ugh.d3 = 0.;	ugh.n3 = 1;	n1 = n2  * n3;	fminmax(ztop,n1,&gmin,&gmax);	ugh.gmax = gmax;	ugh.gmin = gmin;	efwrite(ztop,sizeof(float),n1,topfp);	ierr = fputusghdr(topfp,&ugh);	if(ierr!=0) err(" error output top file");	efclose(topfp);	fminmax(zovt,n1,&gmin,&gmax);	ugh.gmax = gmax;	ugh.gmin = gmin;	efwrite(zovt,sizeof(float),n1,ovtfp);	ierr = fputusghdr(ovtfp,&ugh);	efclose(ovtfp);	if(ierr!=0) err(" error output overhang top file");	fminmax(zovb,n1,&gmin,&gmax);	ugh.gmax = gmax;	ugh.gmin = gmin;	efwrite(zovb,sizeof(float),n1,ovbfp);	ierr = fputusghdr(ovbfp,&ugh);	if(ierr!=0) err(" error output overhang bottom file");	efclose(ovbfp);	fminmax(zbot,n1,&gmin,&gmax);	ugh.gmax = gmax;	ugh.gmin = gmin;	efwrite(zbot,sizeof(float),n1,botfp);	ierr = fputusghdr(botfp,&ugh);	if(ierr!=0) err(" error output bottom file");	efclose(botfp);			exit(0);}