| 1 |
|
|---|
| 2 | int RD_to_XY (double *x, double *y, double ra, double dec, psProjection *proj) {
|
|---|
| 3 |
|
|---|
| 4 | char *type;
|
|---|
| 5 | int i, status, Polynomial, Zenith1, Zenith2, Zenithal, Cartesian, PseudoCyl;
|
|---|
| 6 | double phi, theta;
|
|---|
| 7 | double determ;
|
|---|
| 8 | double X, Y, L, M, Lo, Mo, dL, dM;
|
|---|
| 9 | double sphi, cphi, stht;
|
|---|
| 10 | double salp, calp, sdel, cdel, sdp, cdp;
|
|---|
| 11 | double P, A, Rc;
|
|---|
| 12 |
|
|---|
| 13 | double Ro = proj->R;
|
|---|
| 14 | double Do = proj->D;
|
|---|
| 15 |
|
|---|
| 16 | PseudoCyl = (proj->type == PS_PROJ_AIT) || (proj->type == PS_PROJ_PAR) || (proj->type == PS_PROJ_GLS);
|
|---|
| 17 | Zenith1 = (proj->type == PS_PROJ_TAN);
|
|---|
| 18 | Zenith2 = (proj->type == PS_PROJ_SIN);
|
|---|
| 19 | Zenithal = Zenith1 || Zenith2;
|
|---|
| 20 | if (!Zenithal && !PseudoCyl) return (FALSE);
|
|---|
| 21 |
|
|---|
| 22 | /**** Zenithal Projections ****/
|
|---|
| 23 | if (Zenithal) {
|
|---|
| 24 | sdp = sin(Do);
|
|---|
| 25 | cdp = cos(Do);
|
|---|
| 26 | salp = sin(ra - Ro);
|
|---|
| 27 | calp = cos(ra - Ro);
|
|---|
| 28 | sdel = sin(dec);
|
|---|
| 29 | cdel = cos(dec);
|
|---|
| 30 |
|
|---|
| 31 | stht = sdel*sdp + cdel*cdp*calp; /* sin(theta) */
|
|---|
| 32 | sphi = cdel*salp; /* = cos(theta)*sin(phi) */
|
|---|
| 33 | cphi = cdel*sdp*calp - sdel*cdp; /* = cos(theta)*cos(phi) */
|
|---|
| 34 | if (stht < 0) status = FALSE;
|
|---|
| 35 |
|
|---|
| 36 | if (Zenith1) {
|
|---|
| 37 | L = sphi / stht;
|
|---|
| 38 | M = -cphi / stht;
|
|---|
| 39 | }
|
|---|
| 40 | if (Zenith2) {
|
|---|
| 41 | L = sphi;
|
|---|
| 42 | M = -cphi;
|
|---|
| 43 | }
|
|---|
| 44 | }
|
|---|
| 45 |
|
|---|
| 46 | /**** Other Standard Projections ****/
|
|---|
| 47 | if (PseudoCyl) {
|
|---|
| 48 | if (proj->type === PS_PROJ_AIT) {
|
|---|
| 49 | phi = (ra - coords[0].crval1);
|
|---|
| 50 | theta = (dec - coords[0].crval2);
|
|---|
| 51 | P = 1.0 + cos (theta) * cos (0.5*phi);
|
|---|
| 52 | if (P != 0.0) {
|
|---|
| 53 | A = sqrt (2.0 / P);
|
|---|
| 54 | L = 2.0 * A * cos (theta) * sin (0.5*phi);
|
|---|
| 55 | M = A * sin (theta);
|
|---|
| 56 | } else {
|
|---|
| 57 | L = 0.0;
|
|---|
| 58 | M = 0.0;
|
|---|
| 59 | }
|
|---|
| 60 | }
|
|---|
| 61 | if (proj->type === PS_PROJ_GLS) {
|
|---|
| 62 | phi = ra - Ro;
|
|---|
| 63 | theta = dec - Do;
|
|---|
| 64 | L = phi * cos(theta);
|
|---|
| 65 | M = theta;
|
|---|
| 66 | }
|
|---|
| 67 | if (proj->type === PS_PROJ_PAR) {
|
|---|
| 68 | phi = ra - Ro;
|
|---|
| 69 | theta = dec - Do;
|
|---|
| 70 | L = phi * (2.0*cos(2*theta/3.0) - 1);
|
|---|
| 71 | M = 180.0 * sin (theta/3.0);
|
|---|
| 72 | }
|
|---|
| 73 | }
|
|---|
| 74 |
|
|---|
| 75 | *x = X / proj->Xs;
|
|---|
| 76 | *y = Y / proj->Ys;
|
|---|
| 77 |
|
|---|
| 78 | return (status);
|
|---|
| 79 | }
|
|---|
| 80 |
|
|---|
