Implement viewport code to fix simplification

This fixes #2083

src/util/coordinate.cpp

@@ -29,20 +29,6 @@ Coordinate::Coordinate(const FloatLongitude lon_, const FloatLatitude lat_)
 
 Coordinate::Coordinate(const FixedLongitude lon_, const FixedLatitude lat_) : lon(lon_), lat(lat_)
 {
-#ifndef NDEBUG
-    if (0 != (std::abs(static_cast<int>(lon)) >> 30))
-    {
-        std::bitset<32> x_coordinate_vector(static_cast<int>(lon));
-        SimpleLogger().Write(logDEBUG) << "broken lon: " << lon
-                                       << ", bits: " << x_coordinate_vector;
-    }
-    if (0 != (std::abs(static_cast<int>(lat)) >> 30))
-    {
-        std::bitset<32> y_coordinate_vector(static_cast<int>(lat));
-        SimpleLogger().Write(logDEBUG) << "broken lat: " << lat
-                                       << ", bits: " << y_coordinate_vector;
-    }
-#endif
 }
 
 bool Coordinate::IsValid() const

src/util/coordinate_calculation.cpp

@@ -301,9 +301,26 @@ inline void pixelToDegree(const double shift, double &x, double &y)
     x = (x - b) / shift * 360.0;
     // FIXME needs to be simplified
     const double g = (y - b) / -(shift / (2 * M_PI)) / DEGREE_TO_RAD;
+    static_assert(DEGREE_TO_RAD / (2 * M_PI) - 1/360. < 0.0001, "");
     y = static_cast<double>(util::coordinate_calculation::mercator::yToLat(g));
 }
 
+double degreeToPixel(FloatLongitude lon, unsigned zoom)
+{
+    const double shift = (1u << zoom) * TILE_SIZE;
+    const double b = shift / 2.0;
+    const double x = b * (1 + static_cast<double>(lon) / 180.0);
+    return x;
+}
+
+double degreeToPixel(FloatLatitude lat, unsigned zoom)
+{
+    const double shift = (1u << zoom) * TILE_SIZE;
+    const double b = shift / 2.0;
+    const double y = b * (1. - latToY(lat) / 180.);
+    return y;
+}
+
 // Converts a WMS tile coordinate (z,x,y) into a wsg84 bounding box
 void xyzToWSG84(const int x, const int y, const int z, double &minx, double &miny, double &maxx, double &maxy)
 {