1 files changed, 112 insertions, 0 deletions
diff --git a/src/projections/eck3.cpp b/src/projections/eck3.cpp
new file mode 100644
index 00000000..90376631
--- /dev/null
+++ b/src/projections/eck3.cpp
@@ -0,0 +1,112 @@
+#define PJ_LIB__
+
+#include <errno.h>
+#include <math.h>
+
+#include "projects.h"
+
+PROJ_HEAD(eck3, "Eckert III") "\n\tPCyl, Sph";
+PROJ_HEAD(putp1, "Putnins P1") "\n\tPCyl, Sph";
+PROJ_HEAD(wag6, "Wagner VI") "\n\tPCyl, Sph";
+PROJ_HEAD(kav7, "Kavraisky VII") "\n\tPCyl, Sph";
+
+namespace { // anonymous namespace
+struct pj_opaque {
+    double C_x, C_y, A, B;
+};
+} // 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);
+
+    xy.y = Q->C_y * lp.phi;
+    xy.x = Q->C_x * lp.lam * (Q->A + asqrt(1. - Q->B * lp.phi * 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);
+    double denominator;
+
+    lp.phi = xy.y / Q->C_y;
+    denominator = (Q->C_x * (Q->A + asqrt(1. - Q->B * lp.phi * lp.phi)));
+    if ( denominator == 0.0)
+        lp.lam = HUGE_VAL;
+    else
+        lp.lam = xy.x / denominator;
+    return lp;
+}
+
+
+static PJ *setup(PJ *P) {
+    P->es = 0.;
+    P->inv = s_inverse;
+    P->fwd = s_forward;
+    return P;
+}
+
+
+PJ *PROJECTION(eck3) {
+    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->C_x = 0.42223820031577120149;
+    Q->C_y = 0.84447640063154240298;
+    Q->A = 1.0;
+    Q->B = 0.4052847345693510857755;
+
+    return setup(P);
+}
+
+
+PJ *PROJECTION(kav7) {
+    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;
+
+    /* Defined twice in original code - Using 0.866...,
+     * but leaving the other one here as a safety measure.
+     * Q->C_x = 0.2632401569273184856851; */
+    Q->C_x = 0.8660254037844;
+    Q->C_y = 1.;
+    Q->A = 0.;
+    Q->B = 0.30396355092701331433;
+
+    return setup(P);
+}
+
+
+PJ *PROJECTION(wag6) {
+    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->C_x = Q->C_y = 0.94745;
+    Q->A = 0.0;
+    Q->B = 0.30396355092701331433;
+
+    return setup(P);
+}
+
+
+PJ *PROJECTION(putp1) {
+    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->C_x = 1.89490;
+    Q->C_y = 0.94745;
+    Q->A = -0.5;
+    Q->B = 0.30396355092701331433;
+
+    return setup(P);
+}