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Trim away unused features and layers from sub-tiles

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This commit is contained in:
Eric Fischer 2018-06-13 15:59:52 -07:00
parent f9430a65ef
commit 6a27c19c6b
1 changed files with 25 additions and 1 deletions
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26
vt3.cpp
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@ -114,7 +114,7 @@ static std::vector<mvt_geometry> remove_noop(std::vector<mvt_geometry> geom, std
std::vector<mvt_geometry> out;
for (size_t i = 0; i < geom.size(); i++) {
if (geom[i].op == mvt_moveto && i + 1 < geom.size() && geom[i + 1].op == mvt_moveto) {
if (geom[i].op == mvt_moveto && (i + 1 >= geom.size() || geom[i + 1].op == mvt_moveto)) {
if (geom[i].id != 0) {
#if 0
fprintf(stderr, "Removing a moveto with an id %ld\n", geom[i].id);
@ -320,6 +320,24 @@ void split_feature(mvt_layer const &layer, mvt_feature const &feature, std::vect
}
}
void trim_tile(mvt_tile &tile) {
for (ssize_t i = tile.layers.size() - 1; i >= 0; i--) {
mvt_layer &layer = tile.layers[i];
for (ssize_t j = layer.features.size() - 1; j >= 0; j--) {
mvt_feature &feature = layer.features[j];
if (feature.geometry.size() == 0) {
layer.features.erase(layer.features.begin() + j);
}
}
if (layer.features.size() == 0) {
tile.layers.erase(tile.layers.begin() + i);
}
}
}
mvt_tile split_and_merge(mvt_tile tile, int tile_zoom) {
// Features will be split into an NxN grid of sub-tiles,
// to be merged back together at the end,
@ -368,6 +386,12 @@ mvt_tile split_and_merge(mvt_tile tile, int tile_zoom) {
// Trim unused features from layers, layers from tiles
for (size_t x = 0; x < n; x++) {
for (size_t y = 0; y < n; y++) {
trim_tile(subtiles[x][y]);
}
}
// Write each tile to PBF
// Decode each tile back from PBF