1 files changed, 61 insertions, 7 deletions

diff --git a/src/PJ_hgridshift.c b/src/PJ_hgridshift.c
index 3932ef51..2919a85c 100644
--- a/src/PJ_hgridshift.c
+++ b/src/PJ_hgridshift.c
@@ -1,12 +1,20 @@
 #define PJ_LIB__
 
+#include <errno.h>
+#include <string.h>
 #include <stddef.h>
+#include <time.h>
 
 #include "proj_internal.h"
 #include "projects.h"
 
 PROJ_HEAD(hgridshift, "Horizontal grid shift");
 
+struct pj_opaque_hgridshift {
+    double t_final;
+    double t_epoch;
+};
+
 static XYZ forward_3d(LPZ lpz, PJ *P) {
     PJ_COORD point = {{0,0,0,0}};
     point.lpz = lpz;
@@ -34,21 +42,47 @@ static LPZ reverse_3d(XYZ xyz, PJ *P) {
     return point.lpz;
 }
 
+static PJ_COORD forward_4d(PJ_COORD obs, PJ *P) {
+    struct pj_opaque_hgridshift *Q = (struct pj_opaque_hgridshift *) P->opaque;
+    PJ_COORD point = obs;
 
-static PJ_COORD forward_4d (PJ_COORD obs, PJ *P) {
-    obs.xyz = forward_3d (obs.lpz, P);
-    return obs;
-}
+    /* If transformation is not time restricted, we always call it */
+    if (Q->t_final==0 || Q->t_epoch==0) {
+        point.xyz = forward_3d (obs.lpz, P);
+        return point;
+    }
 
+    /* Time restricted - only apply transform if within time bracket */
+    if (obs.lpzt.t < Q->t_epoch && Q->t_final > Q->t_epoch)
+        point.xyz = forward_3d (obs.lpz, P);
 
-static PJ_COORD reverse_4d (PJ_COORD obs, PJ *P) {
-    obs.lpz = reverse_3d (obs.xyz, P);
-    return obs;
+
+    return point;
 }
 
+static PJ_COORD reverse_4d(PJ_COORD obs, PJ *P) {
+    struct pj_opaque_hgridshift *Q = (struct pj_opaque_hgridshift *) P->opaque;
+    PJ_COORD point = obs;
+
+    /* If transformation is not time restricted, we always call it */
+    if (Q->t_final==0 || Q->t_epoch==0) {
+        point.lpz = reverse_3d (obs.xyz, P);
+        return point;
+    }
+
+    /* Time restricted - only apply transform if within time bracket */
+    if (obs.lpzt.t < Q->t_epoch && Q->t_final > Q->t_epoch)
+        point.lpz = reverse_3d (obs.xyz, P);
+
+    return point;
+}
 
 
 PJ *TRANSFORMATION(hgridshift,0) {
+    struct pj_opaque_hgridshift *Q = pj_calloc (1, sizeof (struct pj_opaque_hgridshift));
+    if (0==Q)
+        return pj_default_destructor (P, ENOMEM);
+    P->opaque = (void *) Q;
 
     P->fwd4d  = forward_4d;
     P->inv4d  = reverse_4d;
@@ -65,6 +99,26 @@ PJ *TRANSFORMATION(hgridshift,0) {
         return pj_default_destructor (P, PJD_ERR_NO_ARGS);
     }
 
+   /* TODO: Refactor into shared function that can be used  */
+   /*       by both vgridshift and hgridshift               */
+   if (pj_param(P->ctx, P->params, "tt_final").i) {
+        Q->t_final = pj_param (P->ctx, P->params, "dt_final").f;
+        if (Q->t_final == 0) {
+            /* a number wasn't passed to +t_final, let's see if it was "now" */
+            /* and set the time accordingly.                                 */
+            if (!strcmp("now", pj_param(P->ctx, P->params, "st_final").s)) {
+                    time_t now;
+                    struct tm *date;
+                    time(&now);
+                    date = localtime(&now);
+                    Q->t_final = 1900.0 + date->tm_year + date->tm_yday/365.0;
+            }
+        }
+    }
+
+   if (pj_param(P->ctx, P->params, "tt_epoch").i)
+        Q->t_epoch = pj_param (P->ctx, P->params, "dt_epoch").f;
+
 
     proj_hgrid_init(P, "grids");
     /* Was gridlist compiled properly? */