Add support for Mercator projections in tiles

This split tiles in the correct

diff --git a/src/data/grits-tms.c b/src/data/grits-tms.c
index cfe84f59a2147c97da5a1e7de7e5bb6f0e21540f..48f5b0c6b75cc194da895f0cfe9f5c43ffa57be6 100644 (file)
--- a/src/data/grits-tms.c
+++ b/src/data/grits-tms.c
@@ -25,63 +25,31 @@
 
 static gchar *_make_uri(GritsTms *tms, GritsTile *tile)
 {
-
-#if 0
-       /* This doesn't make any sense.. */
-       gdouble lon_rad = deg2rad(tile->edge.n + tile->edge.s)/2;
-       gdouble lat_rad = deg2rad(tile->edge.e + tile->edge.w)/2;
-       g_message("%lf,%lf", lat_rad, lon_rad);
-
-       /* Reproject the coordinates to the Mercator projection: */
-       gdouble x = lon_rad;
-       gdouble y = log(tan(lat_rad) + 1.0/cos(lat_rad));
-
-       /* Transform range of x and y to 0 - 1 and shift origin to top left */
-       x = (1.0 + (x / G_PI)) / 2.0;
-       y = (1.0 - (y / G_PI)) / 2.0;
-
-       /* Calculate the number of tiles across the map, n, using 2^zoom */
-       gint zoom = 0;
-       for (GritsTile *tmp = tile->parent; tmp; tmp = tmp->parent)
-               zoom++;
-       gint n = pow(2, zoom);
-
-       /* Multiply x and y by n. Round results down to give tilex and tiley. */
-       gint xtile = x * n;
-       gint ytile = y * n;
-
-       g_message("xy=%f,%f  zoom=%d  n=%d  xy_tiles=%d,%d",
-                       x, y, zoom, n, xtile, ytile);
-#endif
-
-#if 1
-       /* This is broken */
        gint zoom = 0;
        for (GritsTile *tmp = tile->parent; tmp; tmp = tmp->parent)
                zoom++;
        gint breath = pow(2,zoom);
 
-       gdouble lon_pos =  (tile->edge.e+tile->edge.w)/2 + 180;
-       gdouble lat_pos = -(tile->edge.n+tile->edge.s)/2 +  90 - 4.9489;
+       gdouble lat_top = asinh(tan(deg2rad(tile->edge.n)));
+       gdouble lat_bot = asinh(tan(deg2rad(tile->edge.s)));
 
-       gdouble lon_total = 360;
-       gdouble lat_total = 85.0511*2;
+       gdouble lat_mid = (lat_top + lat_bot)/2.0;
+       gdouble lon_mid = (tile->edge.e + tile->edge.w)/2.0;
 
-       gdouble lon_pct = lon_pos / lon_total;
-       gdouble lat_pct = lat_pos / lat_total;
+       gdouble lat_pos = 1.0 - (lat_mid + G_PI) / (2.0*G_PI);
+       gdouble lon_pos = (lon_mid + 180.0) / 360.0;
 
-       gint xtile = lon_pct * breath;
-       gint ytile = lat_pct * breath;
+       gint xtile = lon_pos * breath;
+       gint ytile = lat_pos * breath;
 
-       //g_message("bbok=%f,%f,%f,%f",
+       //g_message("tile=%f,%f,%f,%f t=%p p=%p",
        //              tile->edge.n, tile->edge.s,
-       //              tile->edge.e, tile->edge.w);
-       //g_message("pos=%f,%f total=%f,%f pct=%f,%f tile=%d,%d",
-       //              lon_pos,   lat_pos,
-       //              lon_total, lat_total,
-       //              lon_pct,   lat_pct,
-       //              xtile,     ytile);
-#endif
+       //              tile->edge.e, tile->edge.w, tile, tile->parent);
+       //g_message("top=%lf->%lf bot=%lf->%lf pos=%lf,%lf tile=%d,%d,%d",
+       //              tile->edge.n, lat_top,
+       //              tile->edge.s, lat_bot,
+       //              lat_pos, lon_pos,
+       //              zoom, xtile, ytile);
 
        // http://tile.openstreetmap.org/<zoom>/<xtile>/<ytile>.png
        return g_strdup_printf("%s/%d/%d/%d.%s",

diff --git a/src/grits-viewer.h b/src/grits-viewer.h
index b7ff2166029a18d1bc02dd67624a8a873dde9716..15d9d70cdeffde2ed9c956ba6190165835a4d10d 100644 (file)
--- a/src/grits-viewer.h
+++ b/src/grits-viewer.h
@@ -39,10 +39,10 @@
 #include <glib-object.h>
 
 /* Projections */
-enum {
+typedef enum {
+       GRITS_PROJ_LATLON,
        GRITS_PROJ_MERCATOR,
-       GRITS_PROJ_EQUIRECTANGULAR,
-} GritsProjection;
+} GritsProj;
 
 /* Rendering levels */
 /**

diff --git a/src/objects/grits-tile.c b/src/objects/grits-tile.c
index c8326daeb5ec998d17694c96e288d115e7abce7e..68e71ccb4513aa2bdb8a14d3abc84c1e851cf342 100644 (file)
--- a/src/objects/grits-tile.c
+++ b/src/objects/grits-tile.c
@@ -33,6 +33,7 @@
  */
 
 #include <config.h>
+#include <math.h>
 #include "gtkgl.h"
 #include "grits-tile.h"
 
@@ -61,6 +62,8 @@ GritsTile *grits_tile_new(GritsTile *parent,
        tile->atime  = time(NULL);
        grits_bounds_set_bounds(&tile->coords, 0, 1, 1, 0);
        grits_bounds_set_bounds(&tile->edge, n, s, e, w);
+       if (parent)
+               tile->proj = parent->proj;
        return tile;
 }
 
@@ -133,6 +136,43 @@ static gboolean _grits_tile_precise(GritsPoint *eye, GritsBounds *bounds,
               tile_res < view_res;
 }
 
+static void _grits_tile_split_latlon(GritsTile *tile)
+{
+       const gdouble rows = G_N_ELEMENTS(tile->children);
+       const gdouble cols = G_N_ELEMENTS(tile->children[0]);
+       const gdouble lat_dist = tile->edge.n - tile->edge.s;
+       const gdouble lon_dist = tile->edge.e - tile->edge.w;
+       const gdouble lat_step = lat_dist / rows;
+       const gdouble lon_step = lon_dist / cols;
+
+       int row, col;
+       grits_tile_foreach_index(tile, row, col)
+               tile->children[row][col] = grits_tile_new(tile,
+                       tile->edge.n - lat_step*(row+0),  // north
+                       tile->edge.n - lat_step*(row+1),  // south
+                       tile->edge.w + lon_step*(col+1),  // east
+                       tile->edge.w + lon_step*(col+0)); // west
+}
+
+static void _grits_tile_split_mercator(GritsTile *tile)
+{
+       GritsTile *child = NULL;
+       GritsBounds tmp = tile->edge;
+
+       /* Project */
+       tile->edge.n = asinh(tan(deg2rad(tile->edge.n)));
+       tile->edge.s = asinh(tan(deg2rad(tile->edge.s)));
+
+       _grits_tile_split_latlon(tile);
+
+       /* Convert back to lat-lon */
+       tile->edge = tmp;
+       grits_tile_foreach(tile, child) {
+               child->edge.n = rad2deg(atan(sinh(child->edge.n)));
+               child->edge.s = rad2deg(atan(sinh(child->edge.s)));
+       }
+}
+
 /**
  * grits_tile_update:
  * @root:      the root tile to split
@@ -149,43 +189,37 @@ static gboolean _grits_tile_precise(GritsPoint *eye, GritsBounds *bounds,
  * the tile is recursively subdivided until a sufficient resolution is
  * achieved.
  */
-void grits_tile_update(GritsTile *root, GritsPoint *eye,
+void grits_tile_update(GritsTile *tile, GritsPoint *eye,
                gdouble res, gint width, gint height,
                GritsTileLoadFunc load_func, gpointer user_data)
 {
-       root->atime = time(NULL);
        //g_debug("GritsTile: update - %p->atime = %u",
-       //              root, (guint)root->atime);
-       const gdouble rows = G_N_ELEMENTS(root->children);
-       const gdouble cols = G_N_ELEMENTS(root->children[0]);
-       const gdouble lat_dist = root->edge.n - root->edge.s;
-       const gdouble lon_dist = root->edge.e - root->edge.w;
-       const gdouble lat_step = lat_dist / rows;
-       const gdouble lon_step = lon_dist / cols;
-       int row, col;
-       grits_tile_foreach_index(root, row, col) {
-               GritsBounds edge;
-               edge.n = root->edge.n-(lat_step*(row+0));
-               edge.s = root->edge.n-(lat_step*(row+1));
-               edge.e = root->edge.w+(lon_step*(col+1));
-               edge.w = root->edge.w+(lon_step*(col+0));
-
-               GritsTile **child = &root->children[row][col];
-               if (!_grits_tile_precise(eye, &edge, res,
-                               width/cols, height/rows)) {
-                       if (!*child) {
-                               *child = grits_tile_new(root, edge.n, edge.s,
-                                               edge.e, edge.w);
-                               load_func(*child, user_data);
-                       }
-                       grits_tile_update(*child, eye,
-                                       res, width, height,
-                                       load_func, user_data);
-                       GRITS_OBJECT(*child)->hidden = FALSE;
-               } else if (*child) {
-                       GRITS_OBJECT(*child)->hidden = TRUE;
+       //              tile, (guint)tile->atime);
+
+       if (tile == NULL)
+               return;
+
+       GRITS_OBJECT(tile)->hidden = TRUE;
+       if (_grits_tile_precise(eye, &tile->edge, res, width, height))
+               return;
+       tile->atime = time(NULL);
+       GRITS_OBJECT(tile)->hidden = FALSE;
+
+       if (!tile->data)
+               load_func(tile, user_data);
+
+       if (!tile->children[0][0]) {
+               switch (tile->proj) {
+               case GRITS_PROJ_LATLON:   _grits_tile_split_latlon(tile);   break;
+               case GRITS_PROJ_MERCATOR: _grits_tile_split_mercator(tile); break;
                }
        }
+
+       GritsTile *child;
+       grits_tile_foreach(tile, child)
+               grits_tile_update(child, eye, res, width, height,
+                               load_func, user_data);
+
 }
 
 /**

diff --git a/src/objects/grits-tile.h b/src/objects/grits-tile.h
index 309f4bc0386588768208c0a20fbb38fef4e48d88..f2b706f8bb927e6d14acac79eb2eed27a99f0951 100644 (file)
--- a/src/objects/grits-tile.h
+++ b/src/objects/grits-tile.h
@@ -53,6 +53,9 @@ struct _GritsTile {
 
        /* Last access time (for garbage collection) */
        time_t atime;
+
+       /* Projection used by tile data */
+       GritsProj proj;
 };
 
 struct _GritsTileClass {