From 7243ae76c48161c3b5a20be78ea8f8792ccbbf17 Mon Sep 17 00:00:00 2001
From: Erica Fischer <enf@felt.com>
Date: Fri, 23 Aug 2024 14:10:24 -0700
Subject: [PATCH] Smallest enclosing tile from bbox

---
 Makefile     |  2 +-
 clip.cpp     | 27 +++++++++++++++++++++++++--
 geometry.hpp |  3 +++
 unit.cpp     |  7 +++++++
 4 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/Makefile b/Makefile
index 45f3949f..8891141b 100644
--- a/Makefile
+++ b/Makefile
@@ -74,7 +74,7 @@ tile-join: tile-join.o projection.o mbtiles.o mvt.o memfile.o dirtiles.o jsonpul
 tippecanoe-json-tool: jsontool.o jsonpull/jsonpull.o csv.o text.o geojson-loop.o
 	$(CXX) $(PG) $(LIBS) $(FINAL_FLAGS) $(CXXFLAGS) -o $@ $^ $(LDFLAGS) -lm -lz -lsqlite3 -lpthread
 
-unit: unit.o text.o sort.o mvt.o projection.o
+unit: unit.o text.o sort.o mvt.o projection.o clip.o attribute.o jsonpull/jsonpull.o evaluator.o
 	$(CXX) $(PG) $(LIBS) $(FINAL_FLAGS) $(CXXFLAGS) -o $@ $^ $(LDFLAGS) -lm -lz -lsqlite3 -lpthread
 
 tippecanoe-overzoom: overzoom.o mvt.o clip.o evaluator.o jsonpull/jsonpull.o text.o attribute.o read_json.o projection.o
diff --git a/clip.cpp b/clip.cpp
index c9db2938..10fc91d9 100644
--- a/clip.cpp
+++ b/clip.cpp
@@ -11,6 +11,7 @@
 #include "evaluator.hpp"
 #include "serial.hpp"
 #include "attribute.hpp"
+#include "projection.hpp"
 
 static std::vector<std::pair<double, double>> clip_poly1(std::vector<std::pair<double, double>> &geom,
 							 long long minx, long long miny, long long maxx, long long maxy,
@@ -1184,6 +1185,28 @@ struct index_event {
 	}
 };
 
+void get_quadkey_bounds(long long xmin, long long ymin, long long xmax, long long ymax,
+			unsigned long long *start, unsigned long long *end) {
+	if (xmin < 0 || ymin < 0 || xmax >= 1LL << 32 || ymax >= 1LL << 32) {
+		*start = 0;
+		*end = ULLONG_MAX;
+		return;
+	}
+
+	*start = encode_quadkey(xmin, ymin);
+	*end = encode_quadkey(xmax, ymax);
+
+	for (ssize_t i = 62; i >= 0; i -= 2) {
+		if ((*start & (3LL << i)) != (*end & (3LL << i))) {
+			for (; i >= 0; i -= 2) {
+				*start &= ~(3LL << i);
+				*end |= 3LL << i;
+			}
+			break;
+		}
+	}
+}
+
 mvt_tile assign_to_bins(mvt_tile const &features, std::vector<mvt_layer> const &bins, int z, int x, int y, int detail) {
 	std::vector<index_event> events;
 
@@ -1194,7 +1217,7 @@ mvt_tile assign_to_bins(mvt_tile const &features, std::vector<mvt_layer> const &
 			unsigned long long start, end;
 
 			get_bbox(bins[i].features[j].geometry, &xmin, &ymin, &xmax, &ymax, z, x, y, detail);
-			// get_quadkey_bounds(xmin, xmax, ymin, ymax, &start, &end, z, x, y, detail);
+			get_quadkey_bounds(xmin, xmax, ymin, ymax, &start, &end);
 			events.emplace_back(start, index_event::ENTER, i, j);
 			events.emplace_back(end, index_event::EXIT, i, j);
 		}
@@ -1207,7 +1230,7 @@ mvt_tile assign_to_bins(mvt_tile const &features, std::vector<mvt_layer> const &
 			unsigned long long start, end;
 
 			get_bbox(bins[i].features[j].geometry, &xmin, &ymin, &xmax, &ymax, z, x, y, detail);
-			// get_quadkey_bounds(xmin, xmax, ymin, ymax, &start, &end, z, x, y, detail);
+			get_quadkey_bounds(xmin, xmax, ymin, ymax, &start, &end);
 			events.emplace_back(start, index_event::CHECK, i, j);
 		}
 	}
diff --git a/geometry.hpp b/geometry.hpp
index 2af8307f..d82d1d6f 100644
--- a/geometry.hpp
+++ b/geometry.hpp
@@ -133,4 +133,7 @@ std::string overzoom(std::vector<input_tile> const &tiles, int nz, int nx, int n
 
 draw center_of_mass_mp(const drawvec &dv);
 
+void get_quadkey_bounds(long long xmin, long long ymin, long long xmax, long long ymax,
+			unsigned long long *start, unsigned long long *end);
+
 #endif
diff --git a/unit.cpp b/unit.cpp
index 8d864808..c8f36491 100644
--- a/unit.cpp
+++ b/unit.cpp
@@ -5,6 +5,7 @@
 #include "tile-cache.hpp"
 #include "mvt.hpp"
 #include "projection.hpp"
+#include "geometry.hpp"
 #include <unistd.h>
 #include <limits.h>
 
@@ -144,4 +145,10 @@ TEST_CASE("mvt_geometry bbox") {
 	tile2lonlat(xmax, ymax, 32, &lon, &lat);
 	REQUIRE(std::to_string(lon) == "-122.431641");
 	REQUIRE(std::to_string(lat) == "37.788081");
+
+	unsigned long long start, end;
+	get_quadkey_bounds(xmin, ymin, xmax, ymax, &start, &end);
+	// 22 bits in common, for z11
+	REQUIRE(start == 0x1c84fc0000000000);
+	REQUIRE(end == 0x1c84ffffffffffff);
 }