Add support for Mercator projections in tiles

[grits] / src / objects / grits-tile.c

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);
+
 }
 
 /**