Crunch down memory required per polygon joint

mbtiles.cpp

@@ -99,17 +99,21 @@ sqlite3 *mbtiles_open(char *dbname, char **argv, int forcetable) {
 	return outdb;
 }
 
-void mbtiles_write_tile(sqlite3 *outdb, int z, int tx, int ty, const char *data, int size) {
+unsigned long long fnv1a(std::string const &s) {
 	// Store tiles by a hash of their contents (fnv1a 64-bit)
 	// http://www.isthe.com/chongo/tech/comp/fnv/
 	const unsigned long long fnv_offset_basis = 14695981039346656037u;
 	const unsigned long long fnv_prime = 1099511628211u;
 	unsigned long long h = fnv_offset_basis;
-	for (int i = 0; i < size; i++) {
-		h ^= (unsigned char) data[i];
+	for (size_t i = 0; i < s.size(); i++) {
+		h ^= (unsigned char) s[i];
 		h *= fnv_prime;
 	}
-	std::string hash = std::to_string(h);
+	return h;
+}
+
+void mbtiles_write_tile(sqlite3 *outdb, int z, int tx, int ty, const char *data, int size) {
+	std::string hash = std::to_string(fnv1a(std::string(data, size)));
 
 	// following https://github.com/mapbox/node-mbtiles/blob/master/lib/mbtiles.js
 

mbtiles.hpp

@@ -85,4 +85,6 @@ std::map<std::string, layermap_entry> merge_layermaps(std::vector<std::map<std::
 
 void add_to_file_keys(std::map<std::string, type_and_string_stats> &file_keys, std::string const &layername, type_and_string const &val);
 
+unsigned long long fnv1a(std::string const &s);
+
 #endif

tile.cpp

@@ -1295,30 +1295,31 @@ long long choose_minextent(std::vector<long long> &extents, double f) {
 }
 
 struct joint {
-	draw p1;
-	draw mid;
-	draw p2;
+	long long x : 34;  // enough to wrap around the world either way
+	long long y : 33;  // enough to touch the top and bottom of the world
+
+	unsigned long long p1p2 : 61;
 
 	joint(draw one, draw hinge, draw two) {
 		if (one < two) {
-			p1 = one;
-			p2 = two;
-		} else {
-			p1 = two;
-			p2 = one;
+			std::swap(one, two);
 		}
 
-		mid = hinge;
+		long long coord[4] = {one.x, one.y, two.x, two.y};
+		p1p2 = fnv1a(std::string((const char *) &coord, sizeof(coord)));
+
+		x = hinge.x;
+		y = hinge.y;
 	}
 
 	bool operator<(const joint &o) const {
-		if (mid < o.mid) {
+		if (y < o.y) {
 			return true;
-		} else if (mid == o.mid) {
-			if (p1 < o.p1) {
+		} else if (y == o.y) {
+			if (x < o.x) {
 				return true;
-			} else if (p1 == o.p1) {
-				if (p2 < o.p2) {
+			} else if (x == o.x) {
+				if (p1p2 < o.p1p2) {
 					return true;
 				}
 			}
@@ -2433,10 +2434,10 @@ long long write_tile(decompressor *geoms, std::atomic<long long> *geompos_in, ch
 
 			std::sort(shared_joints.begin(), shared_joints.end());
 			for (size_t i = 0; i + 1 < shared_joints.size(); i++) {
-				if (shared_joints[i].mid == shared_joints[i + 1].mid) {
-					if (shared_joints[i].p1 != shared_joints[i + 1].p1 ||
-					    shared_joints[i].p2 != shared_joints[i + 1].p2) {
-						shared_nodes.push_back(shared_joints[i].mid);
+				if (shared_joints[i].x == shared_joints[i + 1].x &&
+				    shared_joints[i].y == shared_joints[i + 1].y) {
+					if (shared_joints[i].p1p2 != shared_joints[i + 1].p1p2) {
+						shared_nodes.push_back(draw(VT_MOVETO, shared_joints[i].x, shared_joints[i].y));
 					}
 				}
 			}