Add option to order by estimated prominence

README.md

@@ -508,6 +508,8 @@ the same layer, enclose them in an `all` expression so they will all be evaluate
  * `--order-descending-by=`_attribute_: Order features by the specified _attribute_, in reverse alphabetical or numerical order. Multiple `--order-by` and `--order-descending-by` options may be specified, the first being the primary sort key.
  * `--order-smallest-first`: Order features so the smallest geometry comes first in each tile. Multiple `--order-by` and `--order-descending-by` options may be specified, the first being the primary sort key.
  * `--order-largest-first`: Order features so the largest geometry comes first in each tile. Multiple `--order-by` and `--order-descending-by` options may be specified, the first being the primary sort key.
+ * `--order-prominent-first`: Order features so the most prominent geometry (a combination of size and complexity) comes first in each tile. Multiple `--order-by` and `--order-descending-by` options may be specified, the first being the primary sort key.
+ * `--order-prominent-last`: Order features so the most prominent geometry (a combination of size and complexity) comes last in each tile. Multiple `--order-by` and `--order-descending-by` options may be specified, the first being the primary sort key.
 
 ### Adding calculated attributes
 

decode.cpp

@@ -212,7 +212,7 @@ void handle(std::string message, int z, unsigned x, unsigned y, std::set<std::st
 		} else if (coordinate_mode == 2) {  // integer
 			scale = 1;
 		}
-		layer_to_geojson(layer, z, x, y, !pipeline, pipeline, pipeline, false, 0, 0, 0, !force, state, scale);
+		layer_to_geojson(layer, z, x, y, !pipeline, pipeline, pipeline, false, 0, 0, 0, 0, !force, state, scale);
 
 		if (!pipeline) {
 			if (true) {

main.cpp

@@ -87,6 +87,7 @@ std::string attribute_for_id = "";
 std::vector<order_field> order_by;
 bool order_reverse;
 bool order_by_size = false;
+bool order_by_prominence = false;
 
 int prevent[256];
 int additional[256];
@@ -2754,6 +2755,8 @@ int main(int argc, char **argv) {
 		{"order-descending-by", required_argument, 0, '~'},
 		{"order-smallest-first", no_argument, 0, '~'},
 		{"order-largest-first", no_argument, 0, '~'},
+		{"order-prominent-first", no_argument, 0, '~'},
+		{"order-prominent-last", no_argument, 0, '~'},
 
 		{"Adding calculated attributes", 0, 0, 0},
 		{"calculate-feature-density", no_argument, &additional[A_CALCULATE_FEATURE_DENSITY], 1},
@@ -2896,6 +2899,12 @@ int main(int argc, char **argv) {
 			} else if (strcmp(opt, "order-largest-first") == 0) {
 				order_by.push_back(order_field(ORDER_BY_SIZE, true));
 				order_by_size = true;
+			} else if (strcmp(opt, "order-prominent-first") == 0) {
+				order_by.push_back(order_field(ORDER_BY_PROMINENCE, false));
+				order_by_prominence = true;
+			} else if (strcmp(opt, "order-prominent-last") == 0) {
+				order_by.push_back(order_field(ORDER_BY_PROMINENCE, true));
+				order_by_prominence = true;
 			} else if (strcmp(opt, "simplification-at-maximum-zoom") == 0) {
 				maxzoom_simplification = atof_require(optarg, "Mazoom simplification");
 				if (maxzoom_simplification <= 0) {

main.hpp

@@ -69,6 +69,8 @@ extern std::vector<order_field> order_by;
 // not legal UTF-8, so can't appear as a real attribute name
 #define ORDER_BY_SIZE "\200size"
 extern bool order_by_size;
+#define ORDER_BY_PROMINENCE "\200prominence"
+extern bool order_by_prominence;
 
 int mkstemp_cloexec(char *name);
 FILE *fopen_oflag(const char *name, const char *mode, int oflag);

man/tippecanoe.1

@@ -657,6 +657,10 @@ the line or polygon within one tile unit of its proper location. You can probabl
 \fB\fC\-\-order\-smallest\-first\fR: Order features so the smallest geometry comes first in each tile. Multiple \fB\fC\-\-order\-by\fR and \fB\fC\-\-order\-descending\-by\fR options may be specified, the first being the primary sort key.
 .IP \(bu 2
 \fB\fC\-\-order\-largest\-first\fR: Order features so the largest geometry comes first in each tile. Multiple \fB\fC\-\-order\-by\fR and \fB\fC\-\-order\-descending\-by\fR options may be specified, the first being the primary sort key.
+.IP \(bu 2
+\fB\fC\-\-order\-prominent\-first\fR: Order features so the most prominent geometry (a combination of size and complexity) comes first in each tile. Multiple \fB\fC\-\-order\-by\fR and \fB\fC\-\-order\-descending\-by\fR options may be specified, the first being the primary sort key.
+.IP \(bu 2
+\fB\fC\-\-order\-prominent\-last\fR: Order features so the most prominent geometry (a combination of size and complexity) comes last in each tile. Multiple \fB\fC\-\-order\-by\fR and \fB\fC\-\-order\-descending\-by\fR options may be specified, the first being the primary sort key.
 .RE
 .SS Adding calculated attributes
 .RS

plugin.cpp

@@ -54,7 +54,7 @@ void *run_writer(void *a) {
 
 	json_writer state(fp);
 	for (size_t i = 0; i < wa->layers->size(); i++) {
-		layer_to_geojson((*(wa->layers))[i], wa->z, wa->x, wa->y, false, true, false, true, 0, 0, 0, true, state, 0);
+		layer_to_geojson((*(wa->layers))[i], wa->z, wa->x, wa->y, false, true, false, true, 0, 0, 0, 0, true, state, 0);
 	}
 
 	if (fclose(fp) != 0) {

serial.cpp

@@ -192,8 +192,9 @@ static void write_geometry(drawvec const &dv, std::atomic<long long> *fpos, FILE
 void serialize_feature(FILE *geomfile, serial_feature *sf, std::atomic<long long> *geompos, const char *fname, long long wx, long long wy, bool include_minzoom) {
 	serialize_byte(geomfile, sf->t, geompos, fname);
 
-#define FLAG_LAYER 7
+#define FLAG_LAYER 8
 
+#define FLAG_PROMINENCE 7
 #define FLAG_LABEL_POINT 6
 #define FLAG_SEQ 5
 #define FLAG_INDEX 4
@@ -208,6 +209,7 @@ void serialize_feature(FILE *geomfile, serial_feature *sf, std::atomic<long long
 	layer |= (sf->seq != 0) << FLAG_SEQ;
 	layer |= (sf->index != 0) << FLAG_INDEX;
 	layer |= (sf->area != 0) << FLAG_AREA;
+	layer |= (sf->prominence != 0) << FLAG_PROMINENCE;
 	layer |= sf->has_id << FLAG_ID;
 	layer |= sf->has_tippecanoe_minzoom << FLAG_MINZOOM;
 	layer |= sf->has_tippecanoe_maxzoom << FLAG_MAXZOOM;
@@ -239,6 +241,9 @@ void serialize_feature(FILE *geomfile, serial_feature *sf, std::atomic<long long
 	if (sf->area != 0) {
 		serialize_long_long(geomfile, sf->area, geompos, fname);
 	}
+	if (sf->prominence != 0) {
+		serialize_long_long(geomfile, sf->prominence, geompos, fname);
+	}
 
 	serialize_long_long(geomfile, sf->metapos, geompos, fname);
 
@@ -291,6 +296,7 @@ serial_feature deserialize_feature(FILE *geoms, std::atomic<long long> *geompos_
 	sf.index = 0;
 	sf.label_point = 0;
 	sf.area = 0;
+	sf.prominence = 0;
 
 	sf.geometry = decode_geometry(geoms, geompos_in, z, tx, ty, sf.bbox, initial_x[sf.segment], initial_y[sf.segment]);
 	if (sf.layer & (1 << FLAG_INDEX)) {
@@ -302,6 +308,9 @@ serial_feature deserialize_feature(FILE *geoms, std::atomic<long long> *geompos_
 	if (sf.layer & (1 << FLAG_AREA)) {
 		deserialize_long_long_io(geoms, &sf.area, geompos_in);
 	}
+	if (sf.layer & (1 << FLAG_PROMINENCE)) {
+		deserialize_long_long_io(geoms, &sf.prominence, geompos_in);
+	}
 
 	sf.layer >>= FLAG_LAYER;
 
@@ -539,7 +548,16 @@ int serialize_feature(struct serialization_state *sst, serial_feature &sf) {
 	}
 
 	double area = 0;
-	if (additional[A_DROP_SMALLEST_AS_NEEDED] || additional[A_COALESCE_SMALLEST_AS_NEEDED] || order_by_size) {
+	if (additional[A_DROP_SMALLEST_AS_NEEDED] || additional[A_COALESCE_SMALLEST_AS_NEEDED] || order_by_size || order_by_prominence) {
+		double dist = 0;
+		for (size_t i = 1; i < scaled_geometry.size(); i++) {
+			if (scaled_geometry[i].op == VT_LINETO) {
+				double xd = SHIFT_LEFT(scaled_geometry[i].x - scaled_geometry[i - 1].x);
+				double yd = SHIFT_LEFT(scaled_geometry[i].y - scaled_geometry[i - 1].y);
+				dist += sqrt(xd * xd + yd * yd);
+			}
+		}
+
 		if (sf.t == VT_POLYGON) {
 			for (size_t i = 0; i < scaled_geometry.size(); i++) {
 				if (scaled_geometry[i].op == VT_MOVETO) {
@@ -555,18 +573,12 @@ int serialize_feature(struct serialization_state *sst, serial_feature &sf) {
 				}
 			}
 		} else if (sf.t == VT_LINE) {
-			double dist = 0;
-			for (size_t i = 1; i < scaled_geometry.size(); i++) {
-				if (scaled_geometry[i].op == VT_LINETO) {
-					double xd = SHIFT_LEFT(scaled_geometry[i].x - scaled_geometry[i - 1].x);
-					double yd = SHIFT_LEFT(scaled_geometry[i].y - scaled_geometry[i - 1].y);
-					dist += sqrt(xd * xd + yd * yd);
-				}
-			}
 			// treat lines as having the area of a circle with the line as diameter
 			area = M_PI * (dist / 2) * (dist / 2);
 		}
 
+		sf.prominence = sqrt(dist * dist * area);
+
 		// VT_POINT area will be calculated in write_tile from the distance between adjacent features.
 	}
 

serial.hpp

@@ -58,6 +58,7 @@ struct serial_feature {
 	unsigned long long index = 0;
 	unsigned long long label_point = 0;
 	long long area = 0;
+	long long prominence = 0;
 
 	std::vector<long long> keys{};
 	std::vector<long long> values{};

tile.cpp

@@ -97,6 +97,7 @@ struct coalesce {
 	bool has_id = false;
 	unsigned long long id = 0;
 	long long area = 0;
+	long long prominence = 0;
 
 	bool operator<(const coalesce &o) const {
 		int cmp = coalindexcmp(this, &o);
@@ -256,6 +257,11 @@ static mvt_value find_attribute_value(const struct coalesce *c1, std::string key
 		v.type = mvt_double;
 		v.numeric_value.double_value = c1->area;
 		return v;
+	} else if (key == ORDER_BY_PROMINENCE) {
+		mvt_value v;
+		v.type = mvt_double;
+		v.numeric_value.double_value = c1->prominence;
+		return v;
 	}
 
 	const std::vector<long long> &keys1 = c1->keys;
@@ -324,7 +330,7 @@ struct ordercmp {
 	}
 } ordercmp;
 
-void rewrite(drawvec &geom, int z, int nextzoom, int maxzoom, long long *bbox, unsigned tx, unsigned ty, int buffer, int *within, std::atomic<long long> *geompos, FILE **geomfile, const char *fname, signed char t, int layer, long long metastart, signed char feature_minzoom, int child_shards, int max_zoom_increment, long long seq, int tippecanoe_minzoom, int tippecanoe_maxzoom, int segment, unsigned *initial_x, unsigned *initial_y, std::vector<long long> &metakeys, std::vector<long long> &metavals, bool has_id, unsigned long long id, unsigned long long index, unsigned long long label_point, long long area) {
+void rewrite(drawvec &geom, int z, int nextzoom, int maxzoom, long long *bbox, unsigned tx, unsigned ty, int buffer, int *within, std::atomic<long long> *geompos, FILE **geomfile, const char *fname, signed char t, int layer, long long metastart, signed char feature_minzoom, int child_shards, int max_zoom_increment, long long seq, int tippecanoe_minzoom, int tippecanoe_maxzoom, int segment, unsigned *initial_x, unsigned *initial_y, std::vector<long long> &metakeys, std::vector<long long> &metavals, bool has_id, unsigned long long id, unsigned long long index, unsigned long long label_point, long long area, long long prominence) {
 	if (geom.size() > 0 && (nextzoom <= maxzoom || additional[A_EXTEND_ZOOMS])) {
 		int xo, yo;
 		int span = 1 << (nextzoom - z);
@@ -416,6 +422,7 @@ void rewrite(drawvec &geom, int z, int nextzoom, int maxzoom, long long *bbox, u
 					sf.index = index;
 					sf.label_point = label_point;
 					sf.area = area;
+					sf.prominence = prominence;
 					sf.feature_minzoom = feature_minzoom;
 
 					if (metastart < 0) {
@@ -460,6 +467,7 @@ struct partial {
 	bool has_id = 0;
 	ssize_t renamed = 0;
 	long long area = 0;
+	long long prominence = 0;
 	long long clustered = 0;
 	std::set<std::string> need_tilestats;
 	std::map<std::string, accum_state> attribute_accum_state;
@@ -1431,7 +1439,7 @@ serial_feature next_feature(FILE *geoms, std::atomic<long long> *geompos_in, cha
 
 		if (*first_time && pass == 1) { /* only write out the next zoom once, even if we retry */
 			if (sf.tippecanoe_maxzoom == -1 || sf.tippecanoe_maxzoom >= nextzoom) {
-				rewrite(sf.geometry, z, nextzoom, maxzoom, sf.bbox, tx, ty, buffer, within, geompos, geomfile, fname, sf.t, sf.layer, sf.metapos, sf.feature_minzoom, child_shards, max_zoom_increment, sf.seq, sf.tippecanoe_minzoom, sf.tippecanoe_maxzoom, sf.segment, initial_x, initial_y, sf.keys, sf.values, sf.has_id, sf.id, sf.index, sf.label_point, sf.area);
+				rewrite(sf.geometry, z, nextzoom, maxzoom, sf.bbox, tx, ty, buffer, within, geompos, geomfile, fname, sf.t, sf.layer, sf.metapos, sf.feature_minzoom, child_shards, max_zoom_increment, sf.seq, sf.tippecanoe_minzoom, sf.tippecanoe_maxzoom, sf.segment, initial_x, initial_y, sf.keys, sf.values, sf.has_id, sf.id, sf.index, sf.label_point, sf.area, sf.prominence);
 			}
 		}
 
@@ -1606,7 +1614,7 @@ void *run_prefilter(void *v) {
 		decode_meta(sf.keys, sf.values, rpa->stringpool + rpa->pool_off[sf.segment], tmp_layer, tmp_feature);
 		tmp_layer.features.push_back(tmp_feature);
 
-		layer_to_geojson(tmp_layer, 0, 0, 0, false, true, false, true, sf.index, sf.seq, sf.area, true, state, 0);
+		layer_to_geojson(tmp_layer, 0, 0, 0, false, true, false, true, sf.index, sf.seq, sf.area, sf.prominence, true, state, 0);
 	}
 
 	if (fclose(rpa->prefilter_fp) != 0) {
@@ -1963,12 +1971,14 @@ long long write_tile(FILE *geoms, std::atomic<long long> *geompos_in, char *meta
 			if (sf.t == VT_POINT) {
 				if (area_previndex >= sf.index) {
 					sf.area = 1;
+					sf.prominence = 1;
 				} else {
 					double radius = sqrt(sf.index - area_previndex) / 4.0;
 					sf.area = M_PI * radius * radius;
 					if (sf.area < 1) {
 						sf.area = 1;
 					}
+					sf.prominence = sf.area;
 				}
 
 				area_previndex = sf.index;
@@ -2128,6 +2138,7 @@ long long write_tile(FILE *geoms, std::atomic<long long> *geompos_in, char *meta
 					p.index = sf.index;
 					p.renamed = -1;
 					p.area = sf.area;
+					p.prominence = sf.prominence;
 					p.clustered = 0;
 
 					if (line_detail == detail && extra_detail >= 0 && z == maxzoom) {
@@ -2297,6 +2308,7 @@ long long write_tile(FILE *geoms, std::atomic<long long> *geompos_in, char *meta
 					c.id = partials[i].id;
 					c.has_id = partials[i].has_id;
 					c.area = partials[i].area;
+					c.prominence = partials[i].prominence;
 
 					// printf("segment %d layer %lld is %s\n", partials[i].segment, partials[i].layer, (*layer_unmaps)[partials[i].segment][partials[i].layer].c_str());
 

write_json.cpp

@@ -258,7 +258,7 @@ void write_coords(json_writer &state, lonlat const &ll, double scale) {
 	}
 }
 
-void layer_to_geojson(mvt_layer const &layer, unsigned z, unsigned x, unsigned y, bool comma, bool name, bool zoom, bool dropped, unsigned long long index, long long sequence, long long extent, bool complain, json_writer &state, double scale) {
+void layer_to_geojson(mvt_layer const &layer, unsigned z, unsigned x, unsigned y, bool comma, bool name, bool zoom, bool dropped, unsigned long long index, long long sequence, long long area, long long prominence, bool complain, json_writer &state, double scale) {
 	for (size_t f = 0; f < layer.features.size(); f++) {
 		mvt_feature const &feat = layer.features[f];
 
@@ -271,7 +271,7 @@ void layer_to_geojson(mvt_layer const &layer, unsigned z, unsigned x, unsigned y
 			state.json_write_unsigned(feat.id);
 		}
 
-		if (name || zoom || index != 0 || sequence != 0 || extent != 0) {
+		if (name || zoom || index != 0 || sequence != 0 || area != 0 || prominence != 0) {
 			state.json_write_string("tippecanoe");
 			state.json_write_hash();
 
@@ -303,9 +303,13 @@ void layer_to_geojson(mvt_layer const &layer, unsigned z, unsigned x, unsigned y
 				state.json_write_signed(sequence);
 			}
 
-			if (extent != 0) {
+			if (area != 0) {
-				state.json_write_string("extent");
+				state.json_write_string("extent");  // keep misleading terminology for compatibility
-				state.json_write_signed(extent);
+				state.json_write_signed(area);
+			}
+			if (prominence != 0) {
+				state.json_write_string("prominence");
+				state.json_write_signed(prominence);
 			}
 
 			state.json_end_hash();
@@ -505,16 +509,16 @@ void layer_to_geojson(mvt_layer const &layer, unsigned z, unsigned x, unsigned y
 			int outer = 0;
 
 			for (size_t i = 0; i < rings.size(); i++) {
-				double area = 0;
+				double poly_area = 0;
 				for (size_t k = 0; k < rings[i].size(); k++) {
 					if (rings[i][k].op != VT_CLOSEPATH) {
-						area += (double) rings[i][k].x * (double) rings[i][(k + 1) % rings[i].size()].y;
+						poly_area += (double) rings[i][k].x * (double) rings[i][(k + 1) % rings[i].size()].y;
-						area -= (double) rings[i][k].y * (double) rings[i][(k + 1) % rings[i].size()].x;
+						poly_area -= (double) rings[i][k].y * (double) rings[i][(k + 1) % rings[i].size()].x;
 					}
 				}
-				area /= 2;
+				poly_area /= 2;
 
-				areas[i] = area;
+				areas[i] = poly_area;
 				if (areas[i] >= 0 || i == 0) {
 					outer++;
 				}

write_json.hpp

@@ -60,7 +60,7 @@ struct json_writer {
 	void adds(std::string const &s);
 };
 
-void layer_to_geojson(mvt_layer const &layer, unsigned z, unsigned x, unsigned y, bool comma, bool name, bool zoom, bool dropped, unsigned long long index, long long sequence, long long extent, bool complain, json_writer &state, double scale);
+void layer_to_geojson(mvt_layer const &layer, unsigned z, unsigned x, unsigned y, bool comma, bool name, bool zoom, bool dropped, unsigned long long index, long long sequence, long long area, long long prominence, bool complain, json_writer &state, double scale);
 void fprintq(FILE *f, const char *s);
 
 #endif