// Get a RA and Decl from x and y
void reverse(double ra0,double de0,float x,float y,double *ra,double *de)
{
int i;
char pcode[4]="TAN";
double phi,theta;
struct celprm cel;
struct prjprm prj;
double rx,ry;
rx=x/3600.;
ry=y/3600.;
// Initialize Projection Parameters
prj.flag=0;
prj.r0=0.;
for (i=0;i<10;prj.p[i++]=0.);
// Initialize Reference Angles
cel.ref[0]=ra0;
cel.ref[1]=de0;
cel.ref[2]=999.;
cel.ref[3]=999.;
cel.flag=0.;
if (celset(pcode,&cel,&prj)) {
printf("Error in Projection (celset)\n");
return;
} else {
if (celrev(pcode,rx,ry,&prj,&phi,&theta,&cel,ra,de)) {
printf("Error in Projection (celrev)\n");
return;
}
}
return;
}
// Get a x and y from a RA and Decl
void forward(double ra0,double de0,double ra,double de,float *x,float *y)
{
int i;
char pcode[4]="TAN";
double phi,theta;
struct celprm cel;
struct prjprm prj;
double rx,ry;
// Initialize Projection Parameters
prj.flag=0;
prj.r0=0.;
for (i=0;i<10;prj.p[i++]=0.);
// Initialize Reference Angles
cel.ref[0]=ra0;
cel.ref[1]=de0;
cel.ref[2]=999.;
cel.ref[3]=999.;
cel.flag=0.;
if (celset(pcode,&cel,&prj)) {
printf("Error in Projection (celset)\n");
return;
} else {
if (celfwd(pcode,ra,de,&cel,&phi,&theta,&prj,&rx,&ry)) {
printf("Error in Projection (celfwd)\n");
return;
}
}
*x=rx*3600.;
*y=ry*3600.;
return;
}
int main()
{
char text[80];
int ci, crval1, crval2, ilat, ilng, j, k, latpole, lonpole, stat[361],
status;
float xr[512], yr[512];
double lat[181], lng[361], phi[361], theta[361], x[361], y[361];
struct celprm native, celestial;
printf(
"Testing WCSLIB celestial coordinate transformation routines (tcel1.c)\n"
"---------------------------------------------------------------------\n");
/* List status return messages. */
printf("\nList of cel status return values:\n");
for (status = 1; status <= 6; status++) {
printf("%4d: %s.\n", status, cel_errmsg[status]);
}
printf("\n");
/* Initialize. */
celini(&native);
/* Reference angles for the native graticule (in fact, the defaults). */
native.ref[0] = 0.0;
native.ref[1] = 0.0;
/* Set up Bonne's projection with conformal latitude at +35. */
strcpy(native.prj.code, "BON");
native.prj.pv[1] = 35.0;
/* Celestial graticule. */
celini(&celestial);
celestial.prj = native.prj;
/* PGPLOT initialization. */
strcpy(text, "/xwindow");
cpgbeg(0, text, 1, 1);
/* Define pen colours. */
cpgscr(0, 0.0f, 0.0f, 0.0f);
cpgscr(1, 1.0f, 1.0f, 0.0f);
cpgscr(2, 1.0f, 1.0f, 1.0f);
cpgscr(3, 0.5f, 0.5f, 0.8f);
cpgscr(4, 0.8f, 0.5f, 0.5f);
cpgscr(5, 0.8f, 0.8f, 0.8f);
cpgscr(6, 0.5f, 0.5f, 0.8f);
cpgscr(7, 0.8f, 0.5f, 0.5f);
cpgscr(8, 0.3f, 0.5f, 0.3f);
/* Define PGPLOT viewport. */
cpgenv(-180.0f, 180.0f, -90.0f, 140.0f, 1, -2);
/* Loop over CRVAL2, LONPOLE, and LATPOLE with CRVAL1 incrementing by */
/* 15 degrees each time (it has an uninteresting effect). */
crval1 = -180;
for (crval2 = -90; crval2 <= 90; crval2 += 30) {
for (lonpole = -180; lonpole <= 180; lonpole += 30) {
for (latpole = -1; latpole <= 1; latpole += 2) {
/* For the celestial graticule, set the celestial coordinates of
* the reference point of the projection (which for Bonne's
* projection is at the intersection of the native equator and
* prime meridian), the native longitude of the celestial pole,
* and extra information needed to determine the celestial
* latitude of the native pole. These correspond to FITS keywords
* CRVAL1, CRVAL2, LONPOLE, and LATPOLE.
*/
celestial.ref[0] = (double)crval1;
celestial.ref[1] = (double)crval2;
celestial.ref[2] = (double)lonpole;
celestial.ref[3] = (double)latpole;
/* Skip invalid values of LONPOLE. */
if (celset(&celestial)) {
continue;
}
/* Skip redundant values of LATPOLE. */
if (latpole == 1 && fabs(celestial.ref[3]) < 0.1) {
continue;
}
/* Buffer PGPLOT output. */
cpgbbuf();
cpgeras();
/* Write a descriptive title. */
sprintf(text, "Bonne's projection (BON) - 15 degree graticule");
printf("\n%s\n", text);
cpgtext(-180.0f, -100.0f, text);
sprintf(text, "centred on celestial coordinates (%7.2f,%6.2f)",
celestial.ref[0], celestial.ref[1]);
printf("%s\n", text);
cpgtext (-180.0f, -110.0f, text);
sprintf(text, "with north celestial pole at native coordinates "
"(%7.2f,%7.2f)", celestial.ref[2], celestial.ref[3]);
printf("%s\n", text);
cpgtext(-180.0f, -120.0f, text);
/* Draw the native graticule faintly in the background. */
cpgsci(8);
/* Draw native meridians of longitude. */
for (j = 0, ilat = -90; ilat <= 90; ilat++, j++) {
lat[j] = (double)ilat;
}
for (ilng = -180; ilng <= 180; ilng += 15) {
lng[0] = (double)ilng;
if (ilng == -180) lng[0] = -179.99;
if (ilng == 180) lng[0] = 179.99;
/* Dash the longitude of the celestial pole. */
if ((ilng-lonpole)%360 == 0) {
cpgsls(2);
cpgslw(5);
}
cels2x(&native, 1, 181, 1, 1, lng, lat, phi, theta, x, y, stat);
k = 0;
for (j = 0; j < 181; j++) {
if (stat[j]) {
if (k > 1) cpgline(k, xr, yr);
k = 0;
continue;
}
xr[k] = -x[j];
yr[k] = y[j];
k++;
}
cpgline(k, xr, yr);
cpgsls(1);
cpgslw(1);
}
/* Draw native parallels of latitude. */
lng[0] = -179.99;
lng[360] = 179.99;
for (j = 1, ilng = -179; ilng < 180; ilng++, j++) {
lng[j] = (double)ilng;
}
for (ilat = -90; ilat <= 90; ilat += 15) {
lat[0] = (double)ilat;
cels2x(&native, 361, 1, 1, 1, lng, lat, phi, theta, x, y, stat);
k = 0;
for (j = 0; j < 361; j++) {
if (stat[j]) {
if (k > 1) cpgline(k, xr, yr);
k = 0;
continue;
}
xr[k] = -x[j];
yr[k] = y[j];
k++;
}
cpgline(k, xr, yr);
}
/* Draw a colour-coded celestial coordinate graticule. */
ci = 1;
/* Draw celestial meridians of longitude. */
for (j = 0, ilat = -90; ilat <= 90; ilat++, j++) {
lat[j] = (double)ilat;
}
for (ilng = -180; ilng <= 180; ilng += 15) {
lng[0] = (double)ilng;
if (++ci > 7) ci = 2;
cpgsci(ilng?ci:1);
/* Dash the reference longitude. */
if ((ilng-crval1)%360 == 0) {
cpgsls(2);
cpgslw(5);
}
cels2x(&celestial, 1, 181, 1, 1, lng, lat, phi, theta, x, y, stat);
k = 0;
for (j = 0; j < 181; j++) {
if (stat[j]) {
if (k > 1) cpgline(k, xr, yr);
k = 0;
continue;
}
/* Test for discontinuities. */
if (j > 0) {
if (fabs(x[j]-x[j-1]) > 4.0 || fabs(y[j]-y[j-1]) > 4.0) {
if (k > 1) cpgline(k, xr, yr);
k = 0;
}
}
xr[k] = -x[j];
yr[k] = y[j];
k++;
}
cpgline(k, xr, yr);
cpgsls(1);
cpgslw(1);
}
/* Draw celestial parallels of latitude. */
for (j = 0, ilng = -180; ilng <= 180; ilng++, j++) {
lng[j] = (double)ilng;
}
ci = 1;
for (ilat = -90; ilat <= 90; ilat += 15) {
lat[0] = (double)ilat;
if (++ci > 7) ci = 2;
cpgsci(ilat?ci:1);
/* Dash the reference latitude. */
if (ilat == crval2) {
cpgsls(2);
cpgslw(5);
}
cels2x(&celestial, 361, 1, 1, 1, lng, lat, phi, theta, x, y, stat);
k = 0;
for (j = 0; j < 361; j++) {
if (stat[j]) {
if (k > 1) cpgline(k, xr, yr);
k = 0;
continue;
}
/* Test for discontinuities. */
if (j > 0) {
if (fabs(x[j]-x[j-1]) > 4.0 || fabs(y[j]-y[j-1]) > 4.0) {
if (k > 1) cpgline(k, xr, yr);
k = 0;
}
}
xr[k] = -x[j];
yr[k] = y[j];
k++;
}
cpgline(k, xr, yr);
cpgsls(1);
cpgslw(1);
}
/* Flush PGPLOT buffer. */
cpgebuf();
printf(" Type <RETURN> for next page: ");
getc(stdin);
/* Cycle through celestial longitudes. */
if ((crval1 += 15) > 180) crval1 = -180;
/* Skip boring celestial latitudes. */
if (crval2 == 0) break;
}
if (crval2 == 0) break;
}
}
cpgask(0);
cpgend();
return 0;
}
int celset_(int *cel)
{
return celset((struct celprm *)cel);
}