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Factoring out geometry parsing from feature parsing
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@e-n-f
e-n-f committed Nov 21, 2024
1 parent 72731a9 commit 0a4f6fe
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Showing 4 changed files with 134 additions and 124 deletions.
2 changes: 1 addition & 1 deletion geojson.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -199,7 +199,7 @@ int serialize_geojson_feature(struct serialization_state *sst, json_object *geom
}

drawvec dv;
parse_geometry(t, coordinates, dv, VT_MOVETO, sst->fname, sst->line, feature);
parse_coordinates(t, coordinates, dv, VT_MOVETO, sst->fname, sst->line, feature);

serial_feature sf;
sf.layer = layer;
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2 changes: 1 addition & 1 deletion plugin.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -223,7 +223,7 @@ serial_feature parse_feature(json_pull *jp, int z, unsigned x, unsigned y, std::
}

drawvec dv;
parse_geometry(t, coordinates, dv, VT_MOVETO, "Filter output", jp->line, j);
parse_coordinates(t, coordinates, dv, VT_MOVETO, "Filter output", jp->line, j);
if (mb_geometry[t] == VT_POLYGON) {
dv = fix_polygon(dv, false, false);
}
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252 changes: 131 additions & 121 deletions read_json.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -53,7 +53,7 @@ void json_context(json_object *j) {
free(s); // stringify
}

void parse_geometry(int t, json_object *j, drawvec &out, int op, const char *fname, int line, json_object *feature) {
void parse_coordinates(int t, json_object *j, drawvec &out, int op, const char *fname, int line, json_object *feature) {
if (j == NULL || j->type != JSON_ARRAY) {
fprintf(stderr, "%s:%d: expected array for geometry type %d: ", fname, line, t);
json_context(feature);
Expand All @@ -72,7 +72,7 @@ void parse_geometry(int t, json_object *j, drawvec &out, int op, const char *fna
}
}

parse_geometry(within, j->value.array.array[i], out, op, fname, line, feature);
parse_coordinates(within, j->value.array.array[i], out, op, fname, line, feature);
}
} else {
if (j->value.array.length >= 2 && j->value.array.array[0]->type == JSON_NUMBER && j->value.array.array[1]->type == JSON_NUMBER) {
Expand Down Expand Up @@ -178,6 +178,126 @@ static std::vector<mvt_geometry> to_feature(drawvec &geom) {
return out;
}

std::pair<int, drawvec> parse_geometry(json_object *geometry, json_pull *jp, json_object *j,
int z, int x, int y, int extent, bool fix_longitudes) {
json_object *geometry_type = json_hash_get(geometry, "type");
if (geometry_type == NULL) {
fprintf(stderr, "Filter output:%d: null geometry (additional not reported): ", jp->line);
json_context(j);
exit(EXIT_JSON);
}

if (geometry_type->type != JSON_STRING) {
fprintf(stderr, "Filter output:%d: geometry type is not a string: ", jp->line);
json_context(j);
exit(EXIT_JSON);
}

json_object *coordinates = json_hash_get(geometry, "coordinates");
if (coordinates == NULL || coordinates->type != JSON_ARRAY) {
fprintf(stderr, "Filter output:%d: geometry without coordinates array: ", jp->line);
json_context(j);
exit(EXIT_JSON);
}

int t;
for (t = 0; t < GEOM_TYPES; t++) {
if (strcmp(geometry_type->value.string.string, geometry_names[t]) == 0) {
break;
}
}
if (t >= GEOM_TYPES) {
fprintf(stderr, "Filter output:%d: Can't handle geometry type %s: ", jp->line, geometry_type->value.string.string);
json_context(j);
exit(EXIT_JSON);
}

drawvec dv;
parse_coordinates(t, coordinates, dv, VT_MOVETO, "Filter output", jp->line, j);

// handle longitude wraparound
//
// this is supposed to be data for a single tile,
// so any jump from the left hand side edge of the world
// to the right edge, or vice versa, is unexpected,
// so move it to the other side.

if (fix_longitudes && mb_geometry[t] == VT_POLYGON) {
const long long quarter_world = 1LL << 30;
const long long world = 1LL << 32;

bool copy_to_left = false;
bool copy_to_right = false;

for (size_t i = 0; i < dv.size(); i++) {
// is this vertex on a different side of the world
// than the first vertex? then shift this one to match
if (i > 0) {
if ((dv[0].x < quarter_world) && (dv[i].x > 3 * quarter_world)) {
dv[i].x -= world;
}
if ((dv[0].x > 3 * quarter_world) && (dv[i].x < quarter_world)) {
dv[i].x += world;
}
}

// does it stick off the edge of the world?
// then we need another copy on the other side of the world
if (dv[i].x < 0) {
copy_to_right = true;
}
if (dv[i].x > world) {
copy_to_left = true;
}
}

if (copy_to_left) {
size_t n = dv.size();
for (size_t i = 0; i < n; i++) {
dv.emplace_back(dv[i].op, dv[i].x - world, (long long) dv[i].y);
}
}
if (copy_to_right) {
size_t n = dv.size();
for (size_t i = 0; i < n; i++) {
dv.emplace_back(dv[i].op, dv[i].x + world, (long long) dv[i].y);
}
}
}

if (mb_geometry[t] == VT_POLYGON) {
dv = fix_polygon(dv, false, false);
}

// Offset and scale geometry from global to tile
for (size_t i = 0; i < dv.size(); i++) {
long long scale = 1LL << (32 - z);

// offset to tile
dv[i].x -= scale * x;
dv[i].y -= scale * y;

// scale to tile
dv[i].x = std::round(dv[i].x * extent / (double) scale);
dv[i].y = std::round(dv[i].y * extent / (double) scale);
}

if (mb_geometry[t] == VT_POLYGON) {
// don't try scaling up because we may have coordinates
// on the other side of the world
dv = clean_or_clip_poly(dv, z, 256, true, false);
if (dv.size() < 3) {
dv.clear();
}
}
dv = remove_noop(dv, mb_geometry[t], 0);
if (mb_geometry[t] == VT_POLYGON) {
dv = close_poly(dv);
}

return std::pair<int, drawvec>(t, dv);
}

std::vector<mvt_layer> parse_layers(FILE *fp, int z, unsigned x, unsigned y, int extent, bool fix_longitudes) {
std::map<std::string, mvt_layer> ret;
std::shared_ptr<std::string> tile_stringpool = std::make_shared<std::string>();
Expand Down Expand Up @@ -208,14 +328,6 @@ std::vector<mvt_layer> parse_layers(FILE *fp, int z, unsigned x, unsigned y, int
continue;
}

json_object *geometry = json_hash_get(j, "geometry");
if (geometry == NULL) {
fprintf(stderr, "Filter output:%d: filtered feature with no geometry: ", jp->line);
json_context(j);
json_free(j);
exit(EXIT_JSON);
}

json_object *properties = json_hash_get(j, "properties");
if (properties == NULL || (properties->type != JSON_HASH && properties->type != JSON_NULL)) {
fprintf(stderr, "Filter output:%d: feature without properties hash: ", jp->line);
Expand All @@ -224,38 +336,6 @@ std::vector<mvt_layer> parse_layers(FILE *fp, int z, unsigned x, unsigned y, int
exit(EXIT_JSON);
}

json_object *geometry_type = json_hash_get(geometry, "type");
if (geometry_type == NULL) {
fprintf(stderr, "Filter output:%d: null geometry (additional not reported): ", jp->line);
json_context(j);
exit(EXIT_JSON);
}

if (geometry_type->type != JSON_STRING) {
fprintf(stderr, "Filter output:%d: geometry type is not a string: ", jp->line);
json_context(j);
exit(EXIT_JSON);
}

json_object *coordinates = json_hash_get(geometry, "coordinates");
if (coordinates == NULL || coordinates->type != JSON_ARRAY) {
fprintf(stderr, "Filter output:%d: feature without coordinates array: ", jp->line);
json_context(j);
exit(EXIT_JSON);
}

int t;
for (t = 0; t < GEOM_TYPES; t++) {
if (strcmp(geometry_type->value.string.string, geometry_names[t]) == 0) {
break;
}
}
if (t >= GEOM_TYPES) {
fprintf(stderr, "Filter output:%d: Can't handle geometry type %s: ", jp->line, geometry_type->value.string.string);
json_context(j);
exit(EXIT_JSON);
}

std::string layername = "unknown";
json_object *tippecanoe = json_hash_get(j, "tippecanoe");
json_object *layer = NULL;
Expand All @@ -276,88 +356,18 @@ std::vector<mvt_layer> parse_layers(FILE *fp, int z, unsigned x, unsigned y, int
}
auto l = ret.find(layername);

drawvec dv;
parse_geometry(t, coordinates, dv, VT_MOVETO, "Filter output", jp->line, j);

// handle longitude wraparound
//
// this is supposed to be data for a single tile,
// so any jump from the left hand side edge of the world
// to the right edge, or vice versa, is unexpected,
// so move it to the other side.

if (fix_longitudes && mb_geometry[t] == VT_POLYGON) {
const long long quarter_world = 1LL << 30;
const long long world = 1LL << 32;

bool copy_to_left = false;
bool copy_to_right = false;

for (size_t i = 0; i < dv.size(); i++) {
// is this vertex on a different side of the world
// than the first vertex? then shift this one to match
if (i > 0) {
if ((dv[0].x < quarter_world) && (dv[i].x > 3 * quarter_world)) {
dv[i].x -= world;
}
if ((dv[0].x > 3 * quarter_world) && (dv[i].x < quarter_world)) {
dv[i].x += world;
}
}

// does it stick off the edge of the world?
// then we need another copy on the other side of the world
if (dv[i].x < 0) {
copy_to_right = true;
}
if (dv[i].x > world) {
copy_to_left = true;
}
}

if (copy_to_left) {
size_t n = dv.size();
for (size_t i = 0; i < n; i++) {
dv.emplace_back(dv[i].op, dv[i].x - world, (long long) dv[i].y);
}
}
if (copy_to_right) {
size_t n = dv.size();
for (size_t i = 0; i < n; i++) {
dv.emplace_back(dv[i].op, dv[i].x + world, (long long) dv[i].y);
}
}
}

if (mb_geometry[t] == VT_POLYGON) {
dv = fix_polygon(dv, false, false);
json_object *geometry = json_hash_get(j, "geometry");
if (geometry == NULL) {
fprintf(stderr, "Filter output:%d: filtered feature with no geometry: ", jp->line);
json_context(j);
json_free(j);
exit(EXIT_JSON);
}

// Offset and scale geometry from global to tile
for (size_t i = 0; i < dv.size(); i++) {
long long scale = 1LL << (32 - z);

// offset to tile
dv[i].x -= scale * x;
dv[i].y -= scale * y;
std::pair<int, drawvec> parsed_geometry = parse_geometry(geometry, jp, j, z, x, y, extent, fix_longitudes);

// scale to tile
dv[i].x = std::round(dv[i].x * extent / (double) scale);
dv[i].y = std::round(dv[i].y * extent / (double) scale);
}

if (mb_geometry[t] == VT_POLYGON) {
// don't try scaling up because we may have coordinates
// on the other side of the world
dv = clean_or_clip_poly(dv, z, 256, true, false);
if (dv.size() < 3) {
dv.clear();
}
}
dv = remove_noop(dv, mb_geometry[t], 0);
if (mb_geometry[t] == VT_POLYGON) {
dv = close_poly(dv);
}
int t = parsed_geometry.first;
drawvec &dv = parsed_geometry.second;

if (dv.size() > 0) {
mvt_feature feature;
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2 changes: 1 addition & 1 deletion read_json.hpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@ extern int geometry_within[GEOM_TYPES];
extern int mb_geometry[GEOM_TYPES];

void json_context(json_object *j);
void parse_geometry(int t, json_object *j, drawvec &out, int op, const char *fname, int line, json_object *feature);
void parse_coordinates(int t, json_object *j, drawvec &out, int op, const char *fname, int line, json_object *feature);
std::vector<mvt_layer> parse_layers(FILE *fp, int z, unsigned x, unsigned y, int extent, bool fix_longitudes);

serial_val stringify_value(json_object *value, const char *reading, int line, json_object *feature);

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