1 files changed, 102 insertions, 0 deletions
diff --git a/src/projections/ocea.cpp b/src/projections/ocea.cpp
new file mode 100644
index 00000000..0576ace7
--- /dev/null
+++ b/src/projections/ocea.cpp
@@ -0,0 +1,102 @@
+#define PJ_LIB__
+
+#include <errno.h>
+#include <math.h>
+
+#include "projects.h"
+
+PROJ_HEAD(ocea, "Oblique Cylindrical Equal Area") "\n\tCyl, Sph"
+    "lonc= alpha= or\n\tlat_1= lat_2= lon_1= lon_2=";
+
+namespace { // anonymous namespace
+struct pj_opaque {
+    double  rok;
+    double  rtk;
+    double  sinphi;
+    double  cosphi;
+    double  singam;
+    double  cosgam;
+};
+} // anonymous namespace
+
+
+static XY s_forward (LP lp, PJ *P) {           /* Spheroidal, forward */
+    XY xy = {0.0,0.0};
+    struct pj_opaque *Q = static_cast<struct pj_opaque*>(P->opaque);
+    double t;
+    xy.y = sin(lp.lam);
+    t = cos(lp.lam);
+    xy.x = atan((tan(lp.phi) * Q->cosphi + Q->sinphi * xy.y) / t);
+    if (t < 0.)
+        xy.x += M_PI;
+    xy.x *= Q->rtk;
+    xy.y = Q->rok * (Q->sinphi * sin(lp.phi) - Q->cosphi * cos(lp.phi) * xy.y);
+    return xy;
+}
+
+
+static LP s_inverse (XY xy, PJ *P) {           /* Spheroidal, inverse */
+    LP lp = {0.0,0.0};
+    struct pj_opaque *Q = static_cast<struct pj_opaque*>(P->opaque);
+    double t, s;
+
+    xy.y /= Q->rok;
+    xy.x /= Q->rtk;
+    t = sqrt(1. - xy.y * xy.y);
+    lp.phi = asin(xy.y * Q->sinphi + t * Q->cosphi * (s = sin(xy.x)));
+    lp.lam = atan2(t * Q->sinphi * s - xy.y * Q->cosphi,
+        t * cos(xy.x));
+    return lp;
+}
+
+
+PJ *PROJECTION(ocea) {
+    double phi_0=0.0, phi_1, phi_2, lam_1, lam_2, lonz, alpha;
+
+    struct pj_opaque *Q = static_cast<struct pj_opaque*>(pj_calloc (1, sizeof (struct pj_opaque)));
+    if (nullptr==Q)
+        return pj_default_destructor (P, ENOMEM);
+    P->opaque = Q;
+
+    Q->rok = 1. / P->k0;
+    Q->rtk = P->k0;
+    /*If the keyword "alpha" is found in the sentence then use 1point+1azimuth*/
+    if ( pj_param(P->ctx, P->params, "talpha").i) {
+        /*Define Pole of oblique transformation from 1 point & 1 azimuth*/
+        alpha   = pj_param(P->ctx, P->params, "ralpha").f;
+        lonz = pj_param(P->ctx, P->params, "rlonc").f;
+        /*Equation 9-8 page 80 (http://pubs.usgs.gov/pp/1395/report.pdf)*/
+        Q->singam = atan(-cos(alpha)/(-sin(phi_0) * sin(alpha))) + lonz;
+        /*Equation 9-7 page 80 (http://pubs.usgs.gov/pp/1395/report.pdf)*/
+        Q->sinphi = asin(cos(phi_0) * sin(alpha));
+    /*If the keyword "alpha" is NOT found in the sentence then use 2points*/
+    } else {
+        /*Define Pole of oblique transformation from 2 points*/
+        phi_1 = pj_param(P->ctx, P->params, "rlat_1").f;
+        phi_2 = pj_param(P->ctx, P->params, "rlat_2").f;
+        lam_1 = pj_param(P->ctx, P->params, "rlon_1").f;
+        lam_2 = pj_param(P->ctx, P->params, "rlon_2").f;
+        /*Equation 9-1 page 80 (http://pubs.usgs.gov/pp/1395/report.pdf)*/
+        Q->singam = atan2(cos(phi_1) * sin(phi_2) * cos(lam_1) -
+            sin(phi_1) * cos(phi_2) * cos(lam_2),
+            sin(phi_1) * cos(phi_2) * sin(lam_2) -
+            cos(phi_1) * sin(phi_2) * sin(lam_1) );
+
+        /* take care of P->lam0 wrap-around when +lam_1=-90*/
+        if (lam_1 == -M_HALFPI)
+            Q->singam = -Q->singam;
+
+        /*Equation 9-2 page 80 (http://pubs.usgs.gov/pp/1395/report.pdf)*/
+        Q->sinphi = atan(-cos(Q->singam - lam_1) / tan(phi_1));
+    }
+    P->lam0 = Q->singam + M_HALFPI;
+    Q->cosphi = cos(Q->sinphi);
+    Q->sinphi = sin(Q->sinphi);
+    Q->cosgam = cos(Q->singam);
+    Q->singam = sin(Q->singam);
+    P->inv = s_inverse;
+    P->fwd = s_forward;
+    P->es = 0.;
+
+    return P;
+}