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#define PJ_LIB__
#include <errno.h>
#include <math.h>
#include "proj.h"
#include "proj_internal.h"
PROJ_HEAD(igh_o, "Interrupted Goode Homolosine Oceanic View") "\n\tPCyl, Sph";
/*
This projection is a variant of the Interrupted Goode Homolosine
projection that emphasizes ocean areas. The projection is a
compilation of 12 separate sub-projections. Sinusoidal projections
are found near the equator and Mollweide projections are found at
higher latitudes. The transition between the two occurs at 40 degrees
latitude and is represented by `phi_boundary`.
Each sub-projection is assigned an integer label
numbered 1 through 12. Most of this code contains logic to assign
the labels based on latitude (phi) and longitude (lam) regions.
Original Reference:
J. Paul Goode (1925) THE HOMOLOSINE PROJECTION: A NEW DEVICE FOR
PORTRAYING THE EARTH'S SURFACE ENTIRE, Annals of the Association of
American Geographers, 15:3, 119-125, DOI: 10.1080/00045602509356949
*/
C_NAMESPACE PJ *pj_sinu(PJ *), *pj_moll(PJ *);
/*
Transition from sinusoidal to Mollweide projection
Latitude (phi): 40deg 44' 11.8"
*/
static const double phi_boundary = (40 + 44/60. + 11.8/3600.) * DEG_TO_RAD;
static const double d10 = 10 * DEG_TO_RAD;
static const double d20 = 20 * DEG_TO_RAD;
static const double d40 = 40 * DEG_TO_RAD;
static const double d50 = 50 * DEG_TO_RAD;
static const double d60 = 60 * DEG_TO_RAD;
static const double d90 = 90 * DEG_TO_RAD;
static const double d100 = 100 * DEG_TO_RAD;
static const double d110 = 110 * DEG_TO_RAD;
static const double d140 = 140 * DEG_TO_RAD;
static const double d150 = 150 * DEG_TO_RAD;
static const double d160 = 160 * DEG_TO_RAD;
static const double d130 = 130 * DEG_TO_RAD;
static const double d180 = 180 * DEG_TO_RAD;
static const double EPSLN = 1.e-10; /* allow a little 'slack' on zone edge positions */
namespace { // anonymous namespace
struct pj_opaque {
struct PJconsts* pj[12]; \
double dy0;
};
} // anonymous namespace
/*
Assign an integer index representing each of the 12
sub-projection zones based on latitude (phi) and
longitude (lam) ranges.
*/
static PJ_XY igh_o_s_forward (PJ_LP lp, PJ *P) { /* Spheroidal, forward */
PJ_XY xy;
struct pj_opaque *Q = static_cast<struct pj_opaque*>(P->opaque);
int z;
if (lp.phi >= phi_boundary) {
if (lp.lam <= -d90) z = 1;
else if (lp.lam >= d60) z = 3;
else z = 2;
}
else if (lp.phi >= 0) {
if (lp.lam <= -d90) z = 4;
else if (lp.lam >= d60) z = 6;
else z = 5;
}
else if (lp.phi >= -phi_boundary) {
if (lp.lam <= -d60) z = 7;
else if (lp.lam >= d90) z = 9;
else z = 8;
}
else {
if (lp.lam <= -d60) z = 10;
else if (lp.lam >= d90) z = 12;
else z = 11;
}
lp.lam -= Q->pj[z-1]->lam0;
xy = Q->pj[z-1]->fwd(lp, Q->pj[z-1]);
xy.x += Q->pj[z-1]->x0;
xy.y += Q->pj[z-1]->y0;
return xy;
}
static PJ_LP igh_o_s_inverse (PJ_XY xy, PJ *P) { /* Spheroidal, inverse */
PJ_LP lp = {0.0,0.0};
struct pj_opaque *Q = static_cast<struct pj_opaque*>(P->opaque);
const double y90 = Q->dy0 + sqrt(2.0); /* lt=90 corresponds to y=y0+sqrt(2) */
int z = 0;
if (xy.y > y90+EPSLN || xy.y < -y90+EPSLN) /* 0 */
z = 0;
else if (xy.y >= phi_boundary)
if (xy.x <= -d90) z = 1;
else if (xy.x >= d60) z = 3;
else z = 2;
else if (xy.y >= 0)
if (xy.x <= -d90) z = 4;
else if (xy.x >= d60) z = 6;
else z = 5;
else if (xy.y >= -phi_boundary) {
if (xy.x <= -d60) z = 7;
else if (xy.x >= d90) z = 9;
else z = 8;
}
else {
if (xy.x <= -d60) z = 10;
else if (xy.x >= d90) z = 12;
else z = 11;
}
if (z) {
bool ok = false;
xy.x -= Q->pj[z-1]->x0;
xy.y -= Q->pj[z-1]->y0;
lp = Q->pj[z-1]->inv(xy, Q->pj[z-1]);
lp.lam += Q->pj[z-1]->lam0;
switch (z) {
/* Plot projectable ranges with exetension lobes in zones 1 & 3 */
case 1: ok = (lp.lam >= -d180-EPSLN && lp.lam <= -d90+EPSLN) ||
((lp.lam >= d160-EPSLN && lp.lam <= d180+EPSLN) &&
(lp.phi >= d50-EPSLN && lp.phi <= d90+EPSLN)); break;
case 2: ok = (lp.lam >= -d90-EPSLN && lp.lam <= d60+EPSLN); break;
case 3: ok = (lp.lam >= d60-EPSLN && lp.lam <= d180+EPSLN) ||
((lp.lam >= -d180-EPSLN && lp.lam <= -d160+EPSLN) &&
(lp.phi >= d50-EPSLN && lp.phi <= d90+EPSLN)); break;
case 4: ok = (lp.lam >= -d180-EPSLN && lp.lam <= -d90+EPSLN); break;
case 5: ok = (lp.lam >= -d90-EPSLN && lp.lam <= d60+EPSLN); break;
case 6: ok = (lp.lam >= d60-EPSLN && lp.lam <= d180+EPSLN); break;
case 7: ok = (lp.lam >= -d180-EPSLN && lp.lam <= -d60+EPSLN); break;
case 8: ok = (lp.lam >= -d60-EPSLN && lp.lam <= d90+EPSLN); break;
case 9: ok = (lp.lam >= d90-EPSLN && lp.lam <= d180+EPSLN); break;
case 10: ok = (lp.lam >= -d180-EPSLN && lp.lam <= -d60+EPSLN); break;
case 11: ok = (lp.lam >= -d60-EPSLN && lp.lam <= d90+EPSLN) ||
((lp.lam >= d90-EPSLN && lp.lam <= d100+EPSLN) &&
(lp.phi >= -d90-EPSLN && lp.phi <= -d40+EPSLN)); break;
case 12: ok = (lp.lam >= d90-EPSLN && lp.lam <= d180+EPSLN); break;
}
z = (!ok? 0: z); /* projectable? */
}
if (!z) lp.lam = HUGE_VAL;
if (!z) lp.phi = HUGE_VAL;
return lp;
}
static PJ *destructor (PJ *P, int errlev) {
int i;
if (nullptr==P)
return nullptr;
if (nullptr==P->opaque)
return pj_default_destructor (P, errlev);
struct pj_opaque *Q = static_cast<struct pj_opaque*>(P->opaque);
for (i = 0; i < 12; ++i) {
if (Q->pj[i])
Q->pj[i]->destructor(Q->pj[i], errlev);
}
return pj_default_destructor(P, errlev);
}
/*
Zones:
-180 -90 60 180
+---------+----------------+-------------+ Zones 1,2,3,10,11 & 12:
|1 |2 |3 | Mollweide projection
| | | |
+---------+----------------+-------------+ Zones 4,5,6,7,8 & 9:
|4 |5 |6 | Sinusoidal projection
| | | |
0 +---------+--+-------------+--+----------+
|7 |8 |9 |
| | | |
+------------+----------------+----------+
|10 |11 |12 |
| | | |
+------------+----------------+----------+
-180 -60 90 180
*/
static bool setup_zone(PJ *P, struct pj_opaque *Q, int n,
PJ*(*proj_ptr)(PJ*), double x_0,
double y_0, double lon_0) {
if (!(Q->pj[n-1] = proj_ptr(nullptr))) return false;
if (!(Q->pj[n-1] = proj_ptr(Q->pj[n-1]))) return false;
Q->pj[n-1]->ctx = P->ctx;
Q->pj[n-1]->x0 = x_0;
Q->pj[n-1]->y0 = y_0;
Q->pj[n-1]->lam0 = lon_0;
return true;
}
PJ *PROJECTION(igh_o) {
PJ_XY xy1, xy4;
PJ_LP lp = { 0, phi_boundary };
struct pj_opaque *Q = static_cast<struct pj_opaque*>(calloc (1, sizeof (struct pj_opaque)));
if (nullptr==Q)
return pj_default_destructor (P, PROJ_ERR_OTHER /*ENOMEM*/);
P->opaque = Q;
/* sinusoidal zones */
if (!setup_zone(P, Q, 4, pj_sinu, -d140, 0, -d140) ||
!setup_zone(P, Q, 5, pj_sinu, -d10, 0, -d10) ||
!setup_zone(P, Q, 6, pj_sinu, d130, 0, d130) ||
!setup_zone(P, Q, 7, pj_sinu, -d110, 0, -d110) ||
!setup_zone(P, Q, 8, pj_sinu, d20, 0, d20) ||
!setup_zone(P, Q, 9, pj_sinu, d150, 0, d150))
{
return destructor(P, PROJ_ERR_OTHER /*ENOMEM*/);
}
/* mollweide zones */
if (!setup_zone(P, Q, 1, pj_moll, -d140, 0, -d140)) {
return destructor(P, PROJ_ERR_OTHER /*ENOMEM*/);
}
/* y0 ? */
xy1 = Q->pj[0]->fwd(lp, Q->pj[0]); /* zone 1 */
xy4 = Q->pj[3]->fwd(lp, Q->pj[3]); /* zone 4 */
/* y0 + xy1.y = xy4.y for lt = 40d44'11.8" */
Q->dy0 = xy4.y - xy1.y;
Q->pj[0]->y0 = Q->dy0;
/* mollweide zones (cont'd) */
if (!setup_zone(P, Q, 2, pj_moll, -d10, Q->dy0, -d10) ||
!setup_zone(P, Q, 3, pj_moll, d130, Q->dy0, d130) ||
!setup_zone(P, Q, 10, pj_moll, -d110, -Q->dy0, -d110) ||
!setup_zone(P, Q, 11, pj_moll, d20, -Q->dy0, d20) ||
!setup_zone(P, Q, 12, pj_moll, d150, -Q->dy0, d150))
{
return destructor(P, PROJ_ERR_OTHER /*ENOMEM*/);
}
P->inv = igh_o_s_inverse;
P->fwd = igh_o_s_forward;
P->destructor = destructor;
P->es = 0.;
return P;
}
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