Use POSIX definition of pi constant (M_PI) + define tau in terms of pi + better namings + remove deprecated proj4 style definitions

include/mapnik/layer.hpp

@@ -50,7 +50,7 @@ class MAPNIK_DECL layer
 {
 public:
     layer(std::string const& name,
-          std::string const& srs=MAPNIK_LONGLAT_PROJ);
+          std::string const& srs = MAPNIK_GEOGRAPHIC_PROJ);
     // copy
     layer(layer const& l);
     // move

include/mapnik/map.hpp

@@ -153,7 +153,7 @@ public:
      *  @param height Initial map height.
      *  @param srs Initial map projection.
      */
-    Map(int width, int height, std::string const& srs = MAPNIK_LONGLAT_PROJ);
+    Map(int width, int height, std::string const& srs = MAPNIK_GEOGRAPHIC_PROJ);
 
     /*! \brief Copy Constructor.
      *

include/mapnik/util/math.hpp

@@ -27,8 +27,8 @@
 
 namespace mapnik { namespace util {
 
-constexpr double pi = 3.1415926535897932384626433832795;
+constexpr double pi = 3.14159265358979323846;
-constexpr double tau = 6.283185307179586476925286766559;
+constexpr double tau = 2.0 * pi;
 
 template <typename T>
 constexpr T const& clamp(T const& v, T const& lo, T const& hi)
@@ -38,12 +38,12 @@ constexpr T const& clamp(T const& v, T const& lo, T const& hi)
 
 constexpr double degrees(double rad)
 {
-    return rad * (360 / tau);
+    return rad * (180.0 / pi);
 }
 
 constexpr double radians(double deg)
 {
-    return deg * (tau / 360);
+    return deg * (pi / 180);
 }
 
 MAPNIK_DECL double normalize_angle(double angle);

include/mapnik/well_known_srs.hpp

@@ -41,7 +41,7 @@ namespace mapnik {
 
 enum well_known_srs_enum : std::uint8_t {
     WGS_84,
-    G_MERC,
+    WEB_MERC,
     well_known_srs_enum_MAX
 };
 
@@ -53,8 +53,8 @@ constexpr double MERC_MAX_EXTENT = EARTH_RADIUS * util::pi;
 constexpr double MERC_MAX_LATITUDE = 85.0511287798065923778;
               // MERC_MAX_LATITUDE = degrees(2 * atan(exp(pi)) - pi / 2)
 
-extern MAPNIK_DECL std::string const MAPNIK_LONGLAT_PROJ;
+extern MAPNIK_DECL std::string const MAPNIK_GEOGRAPHIC_PROJ;
-extern MAPNIK_DECL std::string const MAPNIK_GMERC_PROJ;
+extern MAPNIK_DECL std::string const MAPNIK_WEBMERCATOR_PROJ;
 
 MAPNIK_DECL boost::optional<bool> is_known_geographic(std::string const& srs);
 MAPNIK_DECL boost::optional<well_known_srs_e> is_well_known_srs(std::string const& srs);

src/map.cpp

@@ -66,7 +66,7 @@ IMPLEMENT_ENUM( aspect_fix_mode_e, aspect_fix_mode_strings )
 Map::Map()
 : width_(400),
     height_(400),
-    srs_(MAPNIK_LONGLAT_PROJ),
+    srs_(MAPNIK_GEOGRAPHIC_PROJ),
     buffer_size_(0),
     background_image_comp_op_(src_over),
     background_image_opacity_(1.0),

src/proj_transform.cpp

@@ -111,12 +111,12 @@ proj_transform::proj_transform(projection const& source,
         bool known_trans = false;
         if (src_k && dest_k)
         {
-            if (*src_k == WGS_84 && *dest_k == G_MERC)
+            if (*src_k == WGS_84 && *dest_k == WEB_MERC)
             {
                 wgs84_to_merc_ = true;
                 known_trans = true;
             }
-            else if (*src_k == G_MERC && *dest_k == WGS_84)
+            else if (*src_k == WEB_MERC && *dest_k == WGS_84)
             {
                 merc_to_wgs84_ = true;
                 known_trans = true;

src/projection.cpp

@@ -94,7 +94,6 @@ void projection::init_proj() const
     if (!proj_)
     {
         proj_ctx_ = proj_context_create();
-        //proj_ = proj_create_crs_to_crs(proj_ctx_, "epsg:4326", params_.c_str(), nullptr);
         proj_ = proj_create(proj_ctx_, params_.c_str());
         if (!proj_ || !proj_ctx_)
         {
@@ -108,18 +107,10 @@ void projection::init_proj() const
             }
             throw proj_init_error(params_);
         }
-        // determine the type of CRS
-        //PJ* crs = proj_create(proj_ctx_, params_.c_str());
-        //if (crs)
-        //if (proj_)
-        //{
-            //PJ_TYPE type = proj_get_type(crs);
         PJ_TYPE type = proj_get_type(proj_);
         is_geographic_ = (type == PJ_TYPE_GEOGRAPHIC_2D_CRS
                           ||
                           type == PJ_TYPE_GEOGRAPHIC_3D_CRS) ? true : false;
-        //}
-        //proj_destroy(crs);
     }
 #endif
 }

src/well_known_srs.cpp

@@ -36,28 +36,27 @@ MAPNIK_DISABLE_WARNING_POP
 
 namespace mapnik {
 
-extern std::string const MAPNIK_LONGLAT_PROJ =
+extern std::string const MAPNIK_GEOGRAPHIC_PROJ =
-    "+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs";
+    "epsg:4326";  //wgs84
 
-extern std::string const MAPNIK_GMERC_PROJ =
+extern std::string const MAPNIK_WEBMERCATOR_PROJ =
-    "+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0"
+    "epsg:3857"; // webmercator
-    " +y_0=0.0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs +over";
 
 static const char * well_known_srs_strings[] = {
-    "mapnik-longlat",
+    MAPNIK_GEOGRAPHIC_PROJ.c_str(),
-    "mapnik-gmerc",
+    MAPNIK_WEBMERCATOR_PROJ.c_str(),
     ""
 };
 
 boost::optional<well_known_srs_e> is_well_known_srs(std::string const& srs)
 {
-    if (srs == "epsg:4326" || srs == MAPNIK_LONGLAT_PROJ)
+    if (srs == MAPNIK_GEOGRAPHIC_PROJ)
     {
         return boost::optional<well_known_srs_e>(mapnik::WGS_84);
     }
-    else if (srs == "epsg:3857" || srs == MAPNIK_GMERC_PROJ)
+    else if (srs == MAPNIK_WEBMERCATOR_PROJ)
     {
-        return boost::optional<well_known_srs_e>(mapnik::G_MERC);
+        return boost::optional<well_known_srs_e>(mapnik::WEB_MERC);
     }
     return boost::optional<well_known_srs_e>();
 }
@@ -65,29 +64,14 @@ boost::optional<well_known_srs_e> is_well_known_srs(std::string const& srs)
 boost::optional<bool> is_known_geographic(std::string const& srs)
 {
     std::string trimmed = util::trim_copy(srs);
-    if (trimmed == "epsg:3857")
+    if (trimmed == MAPNIK_GEOGRAPHIC_PROJ)
-    {
-        return boost::optional<bool>(false);
-    }
-    else if (trimmed == "epsg:4326")
     {
         return boost::optional<bool>(true);
     }
-    else if (srs.find("+proj=") != std::string::npos)
+    else if (trimmed ==  MAPNIK_WEBMERCATOR_PROJ)
-    {
-        if ((srs.find("+proj=longlat") != std::string::npos) ||
-                          (srs.find("+proj=latlong") != std::string::npos) ||
-                          (srs.find("+proj=lonlat") != std::string::npos) ||
-                          (srs.find("+proj=latlon") != std::string::npos)
-                         )
     {
         return boost::optional<bool>(true);
     }
-        else
-        {
-            return boost::optional<bool>(false);
-        }
-    }
     return boost::optional<bool>();
 }
 
@@ -99,7 +83,7 @@ bool lonlat2merc(double & x, double & y)
     auto dx = clamp(x, -180.0, 180.0);
     auto dy = clamp(y, -MERC_MAX_LATITUDE, MERC_MAX_LATITUDE);
     x = EARTH_RADIUS * radians(dx);
-    y = EARTH_RADIUS * std::log(std::tan(radians(90 + dy) / 2));
+    y = EARTH_RADIUS * std::log(std::tan(radians(90.0 + dy) / 2.0));
     return true;
 }
 
@@ -127,7 +111,7 @@ bool merc2lonlat(double & x, double & y)
     auto rx = clamp(x / EARTH_RADIUS, -pi, pi);
     auto ry = clamp(y / EARTH_RADIUS, -pi, pi);
     x = degrees(rx);
-    y = degrees(2 * std::atan(std::exp(ry)) - pi / 2);
+    y = degrees(2.0 * std::atan(std::exp(ry)) - pi / 2.0);
     return true;
 }