1 files changed, 189 insertions, 0 deletions
diff --git a/src/projections/PJ_gn_sinu.cpp b/src/projections/PJ_gn_sinu.cpp
new file mode 100644
index 00000000..530de229
--- /dev/null
+++ b/src/projections/PJ_gn_sinu.cpp
@@ -0,0 +1,189 @@
+#define PJ_LIB__
+
+#include <errno.h>
+#include <math.h>
+
+#include "proj.h"
+#include "projects.h"
+
+PROJ_HEAD(gn_sinu, "General Sinusoidal Series") "\n\tPCyl, Sph\n\tm= n=";
+PROJ_HEAD(sinu, "Sinusoidal (Sanson-Flamsteed)") "\n\tPCyl, Sph&Ell";
+PROJ_HEAD(eck6, "Eckert VI") "\n\tPCyl, Sph";
+PROJ_HEAD(mbtfps, "McBryde-Thomas Flat-Polar Sinusoidal") "\n\tPCyl, Sph";
+
+#define EPS10    1e-10
+#define MAX_ITER 8
+#define LOOP_TOL 1e-7
+
+namespace { // anonymous namespace
+struct pj_opaque {
+    double *en;
+    double m, n, C_x, C_y;
+};
+} // anonymous namespace
+
+
+static XY e_forward (LP lp, PJ *P) {          /* Ellipsoidal, forward */
+    XY xy = {0.0,0.0};
+    double s, c;
+
+    xy.y = pj_mlfn(lp.phi, s = sin(lp.phi), c = cos(lp.phi), static_cast<struct pj_opaque*>(P->opaque)->en);
+    xy.x = lp.lam * c / sqrt(1. - P->es * s * s);
+    return xy;
+}
+
+
+static LP e_inverse (XY xy, PJ *P) {          /* Ellipsoidal, inverse */
+    LP lp = {0.0,0.0};
+    double s;
+
+    if ((s = fabs(lp.phi = pj_inv_mlfn(P->ctx, xy.y, P->es, static_cast<struct pj_opaque*>(P->opaque)->en))) < M_HALFPI) {
+        s = sin(lp.phi);
+        lp.lam = xy.x * sqrt(1. - P->es * s * s) / cos(lp.phi);
+    } else if ((s - EPS10) < M_HALFPI) {
+        lp.lam = 0.;
+    } else {
+        proj_errno_set(P, PJD_ERR_TOLERANCE_CONDITION);
+    }
+
+    return lp;
+}
+
+
+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);
+
+    if (Q->m == 0.0)
+        lp.phi = Q->n != 1. ? aasin(P->ctx,Q->n * sin(lp.phi)): lp.phi;
+    else {
+        double k, V;
+        int i;
+
+        k = Q->n * sin(lp.phi);
+        for (i = MAX_ITER; i ; --i) {
+            lp.phi -= V = (Q->m * lp.phi + sin(lp.phi) - k) /
+                (Q->m + cos(lp.phi));
+            if (fabs(V) < LOOP_TOL)
+                break;
+        }
+        if (!i) {
+            proj_errno_set(P, PJD_ERR_TOLERANCE_CONDITION);
+            return xy;
+        }
+
+    }
+    xy.x = Q->C_x * lp.lam * (Q->m + cos(lp.phi));
+    xy.y = Q->C_y * lp.phi;
+
+    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);
+
+    xy.y /= Q->C_y;
+    lp.phi = (Q->m != 0.0) ? aasin(P->ctx,(Q->m * xy.y + sin(xy.y)) / Q->n) :
+        ( Q->n != 1. ? aasin(P->ctx,sin(xy.y) / Q->n) : xy.y );
+    lp.lam = xy.x / (Q->C_x * (Q->m + cos(xy.y)));
+    return lp;
+}
+
+
+static PJ *destructor (PJ *P, int errlev) {                        /* Destructor */
+    if (nullptr==P)
+        return nullptr;
+
+    if (nullptr==P->opaque)
+        return pj_default_destructor (P, errlev);
+
+    pj_dealloc (static_cast<struct pj_opaque*>(P->opaque)->en);
+    return pj_default_destructor (P, errlev);
+}
+
+
+
+/* for spheres, only */
+static void setup(PJ *P) {
+    struct pj_opaque *Q = static_cast<struct pj_opaque*>(P->opaque);
+    P->es = 0;
+    P->inv = s_inverse;
+    P->fwd = s_forward;
+
+    Q->C_x = (Q->C_y = sqrt((Q->m + 1.) / Q->n))/(Q->m + 1.);
+}
+
+
+PJ *PROJECTION(sinu) {
+    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;
+    P->destructor = destructor;
+
+    if (!(Q->en = pj_enfn(P->es)))
+        return pj_default_destructor (P, ENOMEM);
+
+    if (P->es != 0.0) {
+        P->inv = e_inverse;
+        P->fwd = e_forward;
+    } else {
+        Q->n = 1.;
+        Q->m = 0.;
+        setup(P);
+    }
+    return P;
+}
+
+
+PJ *PROJECTION(eck6) {
+    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;
+    P->destructor = destructor;
+
+    Q->m = 1.;
+    Q->n = 2.570796326794896619231321691;
+    setup(P);
+
+    return P;
+}
+
+
+PJ *PROJECTION(mbtfps) {
+    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;
+    P->destructor = destructor;
+
+    Q->m = 0.5;
+    Q->n = 1.785398163397448309615660845;
+    setup(P);
+
+    return P;
+}
+
+
+PJ *PROJECTION(gn_sinu) {
+    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;
+    P->destructor = destructor;
+
+    if (pj_param(P->ctx, P->params, "tn").i && pj_param(P->ctx, P->params, "tm").i) {
+        Q->n = pj_param(P->ctx, P->params, "dn").f;
+        Q->m = pj_param(P->ctx, P->params, "dm").f;
+        if (Q->n <= 0 || Q->m < 0)
+            return destructor (P, PJD_ERR_INVALID_M_OR_N);
+    } else
+        return destructor (P, PJD_ERR_INVALID_M_OR_N);
+
+    setup(P);
+
+    return P;
+}