Progress toward eliminating decodes of feature indices

geometry.cpp

@@ -944,12 +944,10 @@ drawvec polygon_to_anchor(const drawvec &geom) {
 	return drawvec();
 }
 
-drawvec checkerboard_anchors(drawvec const &geom, int tx, int ty, int z, unsigned long long label_point) {
+drawvec checkerboard_anchors(drawvec const &geom, int tx, int ty, int z, unsigned wx, unsigned wy) {
 	drawvec out;
 
-	// anchor point in world coordinates
-	unsigned wx, wy;
-	decode_index(label_point, &wx, &wy);
+	// wx,wy is anchor point in world coordinates
 
 	// upper left of tile in world coordinates
 	long long tx1 = 0, ty1 = 0;

geometry.hpp

@@ -89,7 +89,7 @@ void check_polygon(drawvec &geom);
 double get_area(const drawvec &geom, size_t i, size_t j);
 double get_mp_area(drawvec &geom);
 drawvec polygon_to_anchor(const drawvec &geom);
-drawvec checkerboard_anchors(drawvec const &geom, int tx, int ty, int z, unsigned long long label_point);
+drawvec checkerboard_anchors(drawvec const &geom, int tx, int ty, int z, unsigned label_x, unsigned label_y);
 
 drawvec simple_clip_poly(drawvec &geom, int z, int buffer, drawvec &shared_nodes, bool prevent_simplify_shared_nodes);
 drawvec simple_clip_poly(drawvec &geom, long long x1, long long y1, long long x2, long long y2, bool prevent_simplify_shared_nodes);

main.cpp

@@ -2499,6 +2499,7 @@ std::pair<int, metadata> read_input(std::vector<source> &sources, char *fname, i
 		long long ip;
 		for (ip = 0; ip < indices; ip++) {
 			unsigned xx, yy;
+			// XXX this will behave oddly if the index is actually H3
 			decode_index(map[ip].ix, &xx, &yy);
 
 			long long nprogress = 100 * ip / indices;

serial.cpp

@@ -186,7 +186,7 @@ std::string serialize_feature(serial_feature *sf, long long wx, long long wy) {
 
 	long long layer = 0;
 	layer |= sf->layer << FLAG_LAYER;
-	layer |= (sf->label_point != 0) << FLAG_LABEL_POINT;
+	layer |= ((sf->label_x | sf->label_y) != 0) << FLAG_LABEL_POINT;
 	layer |= (sf->index != 0) << FLAG_INDEX;
 	layer |= (sf->extent != 0) << FLAG_EXTENT;
 	layer |= sf->has_id << FLAG_ID;
@@ -211,10 +211,13 @@ std::string serialize_feature(serial_feature *sf, long long wx, long long wy) {
 
 	if (sf->index != 0) {
 		serialize_ulong_long(s, sf->index);
+		serialize_ulong_long(s, sf->wx);
+		serialize_ulong_long(s, sf->wy);
 		serialize_ulong_long(s, sf->gap);
 	}
-	if (sf->label_point != 0) {
-		serialize_ulong_long(s, sf->label_point);
+	if ((sf->label_x | sf->label_y) != 0) {
+		serialize_ulong_long(s, sf->label_x);
+		serialize_ulong_long(s, sf->label_y);
 	}
 	if (sf->extent != 0) {
 		serialize_long_long(s, sf->extent);
@@ -261,17 +264,27 @@ serial_feature deserialize_feature(std::string const &geoms, unsigned z, unsigne
 
 	sf.index = 0;
 	sf.gap = 0;
-	sf.label_point = 0;
+	sf.label_x = 0;
+	sf.label_y = 0;
 	sf.extent = 0;
 
 	sf.geometry = decode_geometry(&cp, z, tx, ty, sf.bbox, initial_x[sf.segment], initial_y[sf.segment]);
 
 	if (sf.layer & (1 << FLAG_INDEX)) {
+		unsigned long long wx, wy;
 		deserialize_ulong_long(&cp, &sf.index);
+		deserialize_ulong_long(&cp, &wx);
+		deserialize_ulong_long(&cp, &wy);
+		sf.wx = wx;
+		sf.wy = wy;
 		deserialize_ulong_long(&cp, &sf.gap);
 	}
 	if (sf.layer & (1 << FLAG_LABEL_POINT)) {
-		deserialize_ulong_long(&cp, &sf.label_point);
+		unsigned long long wx, wy;
+		deserialize_ulong_long(&cp, &wx);
+		deserialize_ulong_long(&cp, &wy);
+		sf.label_x = wx;
+		sf.label_y = wy;
 	}
 	if (sf.layer & (1 << FLAG_EXTENT)) {
 		deserialize_long_long(&cp, &sf.extent);
@@ -741,7 +754,8 @@ int serialize_feature(struct serialization_state *sst, serial_feature &sf, std::
 		if (dv.size() > 0) {
 			dv[0].x = SHIFT_LEFT(dv[0].x) & ((1LL << 32) - 1);
 			dv[0].y = SHIFT_LEFT(dv[0].y) & ((1LL << 32) - 1);
-			sf.label_point = encode_index(dv[0].x, dv[0].y);
+			sf.label_x = dv[0].x;
+			sf.label_y = dv[0].y;
 		}
 	}
 

serial.hpp

@@ -118,8 +118,9 @@ struct serial_feature {
 
 	drawvec geometry = drawvec();
 	unsigned long long index = 0;
+	unsigned wx = 0, wy = 0;
 	unsigned long long gap = 0;  // filled in during z0. square of planar distance
-	unsigned long long label_point = 0;
+	unsigned label_x = 0, label_y = 0;
 	long long extent = 0;
 
 	// These fields are not directly serialized, but are used

tile.cpp

@@ -714,7 +714,7 @@ static void *simplification_worker(void *v) {
 
 		if (t == VT_POLYGON && additional[A_GENERATE_POLYGON_LABEL_POINTS]) {
 			t = (*features)[i]->t = VT_POINT;
-			geom = checkerboard_anchors(from_tile_scale(geom, z, out_detail), (*features)[i]->tx, (*features)[i]->ty, z, (*features)[i]->label_point);
+			geom = checkerboard_anchors(from_tile_scale(geom, z, out_detail), (*features)[i]->tx, (*features)[i]->ty, z, (*features)[i]->label_x, (*features)[i]->label_y);
 			to_tile_scale(geom, z, out_detail);
 		}
 
@@ -1131,6 +1131,8 @@ static serial_feature next_feature(decompressor *geoms, std::atomic<long long> *
 				unsigned wx1, wy1;
 				decode_index(next_feature_state.previndex, &wx1, &wy1);
 
+				// find the furthest distance of a vertex in this feature
+				// from the representative point of the previous feature
 				for (auto const &g : sf.geometry) {
 					long long dx = (long long) wx1 - (g.x + ox);
 					long long dy = (long long) wy1 - (g.y + oy);
@@ -2819,7 +2821,7 @@ long long write_tile(decompressor *geoms, std::atomic<long long> *geompos_in, ch
 				}
 
 				if (skipped > 0 || too_many_bytes || too_many_features) {
-					fprintf(stderr, "Can't happen: writing tile even though we skipped\n");
+					fprintf(stderr, "Can't happen: writing tile even though we skipped (%zu %d %d)\n", skipped, too_many_bytes, too_many_features);
 					exit(EXIT_IMPOSSIBLE);
 				}