Implement viewport code to fix simplification

This fixes #2083
2016-03-16 21:31:30 +01:00
parent a77574b3d7
commit 879ccfc8c2
8 changed files with 101 additions and 196 deletions
@@ -80,6 +80,8 @@ const constexpr double TILE_SIZE = 256.0;
 // Converts projected mercator degrees to PX
 const constexpr double DEGREE_TO_PX = detail::MAXEXTENT / 180.0;

+double degreeToPixel(FloatLatitude lat, unsigned zoom);
+double degreeToPixel(FloatLongitude lon, unsigned zoom);
 FloatLatitude yToLat(const double value);
 double latToY(const FloatLatitude latitude);
 void xyzToMercator(const int x, const int y, const int z, double &minx, double &miny, double &maxx, double &maxy);
@@ -1,87 +0,0 @@
-#ifndef UTIL_TILES_HPP
-#define UTIL_TILES_HPP
-
-#include "util/coordinate.hpp"
-
-#include <boost/assert.hpp>
-
-#include <cmath>
-#include <tuple>
-
-// This is a port of the tilebelt algorithm https://github.com/mapbox/tilebelt
-namespace osrm
-{
-namespace util
-{
-namespace tiles
-{
-struct Tile
-{
-    unsigned x;
-    unsigned y;
-    unsigned z;
-};
-
-namespace detail
-{
-// optimized for 32bit integers
-static constexpr unsigned MAX_ZOOM = 32;
-
-// Returns 1-indexed 1..32 of MSB if value > 0 or 0 if value == 0
-inline unsigned getMSBPosition(std::uint32_t value)
-{
-    if (value == 0)
-        return 0;
-    std::uint8_t pos = 1;
-    while (value >>= 1)
-        pos++;
-    return pos;
-}
-
-inline unsigned getBBMaxZoom(const Tile top_left, const Tile bottom_left)
-{
-    auto x_xor = top_left.x ^ bottom_left.x;
-    auto y_xor = top_left.y ^ bottom_left.y;
-    auto lon_msb = detail::getMSBPosition(x_xor);
-    auto lat_msb = detail::getMSBPosition(y_xor);
-    return MAX_ZOOM - std::max(lon_msb, lat_msb);
-}
-}
-
-inline Tile pointToTile(const FloatLongitude lon, const FloatLatitude lat)
-{
-    auto sin_lat = std::sin(static_cast<double>(lat) * M_PI / 180.);
-    auto p2z = std::pow(2, detail::MAX_ZOOM);
-    unsigned x = p2z * (static_cast<double>(lon) / 360. + 0.5);
-    unsigned y = p2z * (0.5 - 0.25 * std::log((1 + sin_lat) / (1 - sin_lat)) / M_PI);
-
-    return Tile{x, y, detail::MAX_ZOOM};
-}
-
-inline Tile getBBMaxZoomTile(const FloatLongitude min_lon,
-                             const FloatLatitude min_lat,
-                             const FloatLongitude max_lon,
-                             const FloatLatitude max_lat)
-{
-    const auto top_left = pointToTile(min_lon, min_lat);
-    const auto bottom_left = pointToTile(max_lon, max_lat);
-    BOOST_ASSERT(top_left.z == detail::MAX_ZOOM);
-    BOOST_ASSERT(bottom_left.z == detail::MAX_ZOOM);
-
-    const auto max_zoom = detail::getBBMaxZoom(top_left, bottom_left);
-
-    if (max_zoom == 0)
-    {
-        return Tile{0, 0, 0};
-    }
-
-    auto x = top_left.x >> (detail::MAX_ZOOM - max_zoom);
-    auto y = top_left.y >> (detail::MAX_ZOOM - max_zoom);
-
-    return Tile{x, y, max_zoom};
-}
-}
-}
-}
-
-#endif
@@ -0,0 +1,48 @@
+#ifndef UTIL_VIEWPORT_HPP
+#define UTIL_VIEWPORT_HPP
+
+#include "util/coordinate.hpp"
+#include "util/coordinate_calculation.hpp"
+
+#include <boost/assert.hpp>
+
+#include <cmath>
+#include <tuple>
+
+// Port of https://github.com/mapbox/geo-viewport
+
+namespace osrm
+{
+namespace util
+{
+namespace viewport
+{
+
+namespace detail
+{
+static constexpr unsigned MAX_ZOOM = 18;
+static constexpr unsigned MIN_ZOOM = 1;
+// this is an upper bound to current display sizes
+static constexpr double VIEWPORT_WIDTH = 8 * coordinate_calculation::mercator::TILE_SIZE;
+static constexpr double VIEWPORT_HEIGHT = 5 * coordinate_calculation::mercator::TILE_SIZE;
+static double INV_LOG_2 = 1. / std::log(2);
+}
+
+unsigned getFittedZoom(util::Coordinate south_west, util::Coordinate north_east)
+{
+    const auto min_x = coordinate_calculation::mercator::degreeToPixel(toFloating(south_west.lon), detail::MAX_ZOOM);
+    const auto max_y = coordinate_calculation::mercator::degreeToPixel(toFloating(south_west.lat), detail::MAX_ZOOM);
+    const auto max_x = coordinate_calculation::mercator::degreeToPixel(toFloating(north_east.lon), detail::MAX_ZOOM);
+    const auto min_y = coordinate_calculation::mercator::degreeToPixel(toFloating(north_east.lat), detail::MAX_ZOOM);
+    const double width_ratio = (max_x - min_x) / detail::VIEWPORT_WIDTH;
+    const double height_ratio = (max_y - min_y) / detail::VIEWPORT_HEIGHT;
+    const auto zoom = detail::MAX_ZOOM - std::max(std::log(width_ratio), std::log(height_ratio)) * detail::INV_LOG_2;
+
+    return std::max<unsigned>(detail::MIN_ZOOM, zoom);
+}
+
+}
+}
+}
+
+#endif