+gdouble _gis_tile_get_min_dist(GisTile *self,
+ gdouble lat, gdouble lon, gdouble elev)
+{
+ gdouble tlat = lat > self->edge.n ? self->edge.n :
+ lat < self->edge.s ? self->edge.s : lat;
+ gdouble tlon = lon > self->edge.e ? self->edge.e :
+ lon < self->edge.w ? self->edge.w : lon;
+ gdouble telev = 0; // TODO: elevation at rlat,rlon
+ //if (lat == tlat && lon == tlon)
+ // return elev; /* Shortcut? */
+ gdouble a[3], b[3];
+ lle2xyz( lat, lon, elev, a+0, a+1, a+2);
+ lle2xyz(tlat, tlon, telev, b+0, b+1, b+2);
+ return distd(a, b);
+}
+
+gboolean _gis_tile_needs_split(GisTile *self,
+ gdouble max_res, gint width, gint height,
+ gdouble lat, gdouble lon, gdouble elev)
+{
+ gdouble lat_point = self->edge.n < 0 ? self->edge.n :
+ self->edge.s > 0 ? self->edge.s : 0;
+ gdouble min_dist = _gis_tile_get_min_dist(self, lat, lon, elev);
+ gdouble view_res = MPPX(min_dist);
+ gdouble lon_dist = self->edge.e - self->edge.w;
+ gdouble tile_res = ll2m(lon_dist, lat_point)/width;
+
+ /* This isn't really right, but it helps with memory since we don't (yet?) test if the tile
+ * would be drawn */
+ gdouble scale = elev / min_dist;
+ view_res /= scale;
+ //g_message("tile=(%7.2f %7.2f %7.2f %7.2f) "
+ // "eye=(%9.1f %9.1f %9.1f) "
+ // "elev=%9.1f / dist=%9.1f = %f",
+ // self->edge.n, self->edge.s, self->edge.e, self->edge.w,
+ // lat, lon, elev,
+ // elev, min_dist, scale);
+
+ if (tile_res < max_res)
+ return FALSE;
+ return view_res < tile_res;
+}
+
+void gis_tile_update(GisTile *self,
+ gdouble res, gint width, gint height,
+ gdouble lat, gdouble lon, gdouble elev,
+ GisTileLoadFunc load_func, gpointer user_data)
+{
+ self->atime = time(NULL);
+ //g_debug("GisTile: update - %p->atime = %u", self, (guint)self->atime);
+ gdouble lat_dist = self->edge.n - self->edge.s;
+ gdouble lon_dist = self->edge.e - self->edge.w;
+ if (_gis_tile_needs_split(self, res, width, height, lat, lon, elev)) {
+ gdouble lat_step = lat_dist / G_N_ELEMENTS(self->children);
+ gdouble lon_step = lon_dist / G_N_ELEMENTS(self->children[0]);
+ int x, y;
+ gis_tile_foreach_index(self, x, y) {
+ if (!self->children[x][y]) {
+ self->children[x][y] = gis_tile_new(self,
+ self->edge.n-(lat_step*(x+0)),
+ self->edge.n-(lat_step*(x+1)),
+ self->edge.w+(lon_step*(y+1)),
+ self->edge.w+(lon_step*(y+0)));
+ load_func(self->children[x][y], user_data);
+ }
+ gis_tile_update(self->children[x][y],
+ res, width, height,
+ lat, lon, elev,
+ load_func, user_data);
+ }
+ }
+}
+
+GisTile *gis_tile_gc(GisTile *self, time_t atime,
+ GisTileFreeFunc free_func, gpointer user_data)
+{
+ if (!self)
+ return NULL;
+ gboolean has_children = FALSE;
+ int x, y;
+ gis_tile_foreach_index(self, x, y) {
+ self->children[x][y] = gis_tile_gc(
+ self->children[x][y], atime,
+ free_func, user_data);
+ if (self->children[x][y])
+ has_children = TRUE;
+ }
+ //g_debug("GisTile: gc - %p->atime=%u < atime=%u",
+ // self, (guint)self->atime, (guint)atime);
+ if (!has_children && self->atime < atime && self->data) {
+ free_func(self, user_data);
+ g_free(self);
+ return NULL;
+ }
+ return self;
+}