proj_hgrid_value(): do not apply compensation for west-oriented longitude_offset. Fixes regression due to grid refactoring work on proj=deformation use case

3 files changed, 34 insertions, 24 deletions

diff --git a/src/apply_gridshift.cpp b/src/apply_gridshift.cpp
index b994474b..4ef86fc0 100644
--- a/src/apply_gridshift.cpp
+++ b/src/apply_gridshift.cpp
@@ -119,7 +119,7 @@ ListOfHGrids proj_hgrid_init(PJ* P, const char *gridkey) {
 
 typedef struct { pj_int32 lam, phi; } ILP;
 
-static PJ_LP nad_intr(PJ_LP t, const HorizontalShiftGrid* grid) {
+static PJ_LP nad_intr(PJ_LP t, const HorizontalShiftGrid* grid, bool compensateNTConvention) {
 	PJ_LP val, frct;
 	ILP indx;
 	int in;
@@ -164,10 +164,10 @@ static PJ_LP nad_intr(PJ_LP t, const HorizontalShiftGrid* grid) {
         float f10Lon = 0, f10Lat = 0;
         float f01Lon = 0, f01Lat = 0;
         float f11Lon = 0, f11Lat = 0;
-	if( !grid->valueAt(indx.lam, indx.phi, f00Lon, f00Lat) ||
-            !grid->valueAt(indx.lam + 1, indx.phi, f10Lon, f10Lat) ||
-            !grid->valueAt(indx.lam, indx.phi + 1, f01Lon, f01Lat) ||
-            !grid->valueAt(indx.lam + 1, indx.phi + 1, f11Lon, f11Lat) )
+	if( !grid->valueAt(indx.lam, indx.phi, compensateNTConvention, f00Lon, f00Lat) ||
+            !grid->valueAt(indx.lam + 1, indx.phi, compensateNTConvention, f10Lon, f10Lat) ||
+            !grid->valueAt(indx.lam, indx.phi + 1, compensateNTConvention, f01Lon, f01Lat) ||
+            !grid->valueAt(indx.lam + 1, indx.phi + 1, compensateNTConvention, f11Lon, f11Lat) )
         {
             return val;
         }
@@ -210,7 +210,7 @@ PJ_LP nad_cvt(projCtx ctx, PJ_LP in, int inverse, const HorizontalShiftGrid* gri
 
     tb.lam = adjlon (tb.lam - M_PI) + M_PI;
 
-    t = nad_intr (tb, grid);
+    t = nad_intr (tb, grid, true);
     if (t.lam == HUGE_VAL)
         return t;
 
@@ -224,7 +224,7 @@ PJ_LP nad_cvt(projCtx ctx, PJ_LP in, int inverse, const HorizontalShiftGrid* gri
     t.phi = tb.phi - t.phi;
 
     do {
-        del = nad_intr(t, grid);
+        del = nad_intr(t, grid, true);
 
         /* We can possibly go outside of the initial guessed grid, so try */
         /* to fetch a new grid into which iterate... */
@@ -297,7 +297,7 @@ PJ_LP proj_hgrid_value(PJ *P, const ListOfHGrids& grids, PJ_LP lp) {
 
     lp.lam = adjlon(lp.lam - M_PI) + M_PI;
 
-    out = nad_intr(lp, grid);
+    out = nad_intr(lp, grid, false);
 
     if (out.lam == HUGE_VAL || out.phi == HUGE_VAL) {
         pj_ctx_set_errno(P->ctx, PJD_ERR_GRID_AREA);
diff --git a/src/grids.cpp b/src/grids.cpp
index a3d984de..5a99106b 100644
--- a/src/grids.cpp
+++ b/src/grids.cpp
@@ -1431,14 +1431,15 @@ class NullHorizontalShiftGrid : public HorizontalShiftGrid {
 
     bool isNullGrid() const override { return true; }
 
-    bool valueAt(int, int, float &lonShift, float &latShift) const override;
+    bool valueAt(int, int, bool, float &lonShift,
+                 float &latShift) const override;
 
     void reassign_context(PJ_CONTEXT *) override {}
 };
 
 // ---------------------------------------------------------------------------
 
-bool NullHorizontalShiftGrid::valueAt(int, int, float &lonShift,
+bool NullHorizontalShiftGrid::valueAt(int, int, bool, float &lonShift,
                                       float &latShift) const {
     lonShift = 0.0f;
     latShift = 0.0f;
@@ -1471,7 +1472,8 @@ class NTv1Grid : public HorizontalShiftGrid {
 
     ~NTv1Grid() override;
 
-    bool valueAt(int, int, float &lonShift, float &latShift) const override;
+    bool valueAt(int, int, bool, float &lonShift,
+                 float &latShift) const override;
 
     static NTv1Grid *open(PJ_CONTEXT *ctx, std::unique_ptr<File> fp,
                           const std::string &filename);
@@ -1549,7 +1551,8 @@ NTv1Grid *NTv1Grid::open(PJ_CONTEXT *ctx, std::unique_ptr<File> fp,
 
 // ---------------------------------------------------------------------------
 
-bool NTv1Grid::valueAt(int x, int y, float &lonShift, float &latShift) const {
+bool NTv1Grid::valueAt(int x, int y, bool compensateNTConvention,
+                       float &lonShift, float &latShift) const {
     assert(x >= 0 && y >= 0 && x < m_width && y < m_height);
 
     double two_doubles[2];
@@ -1566,7 +1569,8 @@ bool NTv1Grid::valueAt(int x, int y, float &lonShift, float &latShift) const {
     /* convert seconds to radians */
     latShift = static_cast<float>(two_doubles[0] * ((M_PI / 180.0) / 3600.0));
     // west longitude positive convention !
-    lonShift = -static_cast<float>(two_doubles[1] * ((M_PI / 180.0) / 3600.0));
+    lonShift = (compensateNTConvention ? -1 : 1) *
+               static_cast<float>(two_doubles[1] * ((M_PI / 180.0) / 3600.0));
 
     return true;
 }
@@ -1589,7 +1593,8 @@ class CTable2Grid : public HorizontalShiftGrid {
 
     ~CTable2Grid() override;
 
-    bool valueAt(int, int, float &lonShift, float &latShift) const override;
+    bool valueAt(int, int, bool, float &lonShift,
+                 float &latShift) const override;
 
     static CTable2Grid *open(PJ_CONTEXT *ctx, std::unique_ptr<File> fp,
                              const std::string &filename);
@@ -1659,8 +1664,8 @@ CTable2Grid *CTable2Grid::open(PJ_CONTEXT *ctx, std::unique_ptr<File> fp,
 
 // ---------------------------------------------------------------------------
 
-bool CTable2Grid::valueAt(int x, int y, float &lonShift,
-                          float &latShift) const {
+bool CTable2Grid::valueAt(int x, int y, bool compensateNTConvention,
+                          float &lonShift, float &latShift) const {
     assert(x >= 0 && y >= 0 && x < m_width && y < m_height);
 
     float two_floats[2];
@@ -1675,7 +1680,7 @@ bool CTable2Grid::valueAt(int x, int y, float &lonShift,
 
     latShift = two_floats[1];
     // west longitude positive convention !
-    lonShift = -two_floats[0];
+    lonShift = (compensateNTConvention ? -1 : 1) * two_floats[0];
 
     return true;
 }
@@ -1725,7 +1730,8 @@ class NTv2Grid : public HorizontalShiftGrid {
           m_name(nameIn), m_ctx(ctx), m_fp(fp), m_offset(offsetIn),
           m_mustSwap(mustSwapIn) {}
 
-    bool valueAt(int, int, float &lonShift, float &latShift) const override;
+    bool valueAt(int, int, bool, float &lonShift,
+                 float &latShift) const override;
 
     void reassign_context(PJ_CONTEXT *ctx) override {
         m_ctx = ctx;
@@ -1735,7 +1741,8 @@ class NTv2Grid : public HorizontalShiftGrid {
 
 // ---------------------------------------------------------------------------
 
-bool NTv2Grid::valueAt(int x, int y, float &lonShift, float &latShift) const {
+bool NTv2Grid::valueAt(int x, int y, bool compensateNTConvention,
+                       float &lonShift, float &latShift) const {
     assert(x >= 0 && y >= 0 && x < m_width && y < m_height);
 
     float two_float[2];
@@ -1755,7 +1762,8 @@ bool NTv2Grid::valueAt(int x, int y, float &lonShift, float &latShift) const {
     /* convert seconds to radians */
     latShift = static_cast<float>(two_float[0] * ((M_PI / 180.0) / 3600.0));
     // west longitude positive convention !
-    lonShift = -static_cast<float>(two_float[1] * ((M_PI / 180.0) / 3600.0));
+    lonShift = (compensateNTConvention ? -1 : 1) *
+               static_cast<float>(two_float[1] * ((M_PI / 180.0) / 3600.0));
     return true;
 }
 
@@ -1938,7 +1946,8 @@ class GTiffHGrid : public HorizontalShiftGrid {
 
     ~GTiffHGrid() override;
 
-    bool valueAt(int x, int y, float &lonShift, float &latShift) const override;
+    bool valueAt(int x, int y, bool, float &lonShift,
+                 float &latShift) const override;
 
     void insertGrid(PJ_CONTEXT *ctx, std::unique_ptr<GTiffHGrid> &&subgrid);
 
@@ -1968,7 +1977,8 @@ GTiffHGrid::~GTiffHGrid() = default;
 
 // ---------------------------------------------------------------------------
 
-bool GTiffHGrid::valueAt(int x, int y, float &lonShift, float &latShift) const {
+bool GTiffHGrid::valueAt(int x, int y, bool, float &lonShift,
+                         float &latShift) const {
     if (!m_grid->valueAt(m_idxLatShift, x, y, latShift) ||
         !m_grid->valueAt(m_idxLonShift, x, y, lonShift)) {
         return false;
diff --git a/src/grids.hpp b/src/grids.hpp
index fde3eb3e..aa852ef6 100644
--- a/src/grids.hpp
+++ b/src/grids.hpp
@@ -132,8 +132,8 @@ class HorizontalShiftGrid : public Grid {
     const HorizontalShiftGrid *gridAt(double lon, double lat) const;
 
     // x = 0 is western-most column, y = 0 is southern-most line
-    virtual bool valueAt(int x, int y, float &lonShift,
-                         float &latShift) const = 0;
+    virtual bool valueAt(int x, int y, bool compensateNTConvention,
+                         float &lonShift, float &latShift) const = 0;
 
     virtual void reassign_context(PJ_CONTEXT *ctx) = 0;
 };