Merge any leftover feature remnants onto some feature.

Add a test for coalescing small features onto large ones.

CHANGELOG.md

@@ -1,3 +1,8 @@
+## 1.25.0
+
+* Add --coalesce-smallest-as-needed strategy for reducing tile sizes
+* Add --stats option to tipppecanoe-decode
+
 ## 1.24.1
 
 * Limit the size and depth of the string pool for better performance

tile.cpp

@@ -1575,7 +1575,7 @@ long long write_tile(FILE *geoms, long long *geompos_in, char *metabase, char *s
 
 			if (coalesced_geometry.size() != 0) {
 				for (ssize_t i = coalesced_geometry.size() - 1; i >= 0; i--) {
-					if (coalesced_geometry[i].t == sf.t) {
+					if (coalesced_geometry[i].t == sf.t && coalesced_geometry[i].layer == sf.layer) {
 						for (size_t j = 0; j < coalesced_geometry[i].geometry.size(); j++) {
 							sf.geometry.push_back(coalesced_geometry[i].geometry[j]);
 						}
@@ -1639,6 +1639,20 @@ long long write_tile(FILE *geoms, long long *geompos_in, char *metabase, char *s
 			merge_previndex = sf.index;
 		}
 
+		// Attach any pieces that were waiting to be coalesced onto some features that did make it.
+		for (ssize_t i = coalesced_geometry.size() - 1; i >= 0; i--) {
+			for (size_t j = 0; j < partials.size(); j++) {
+				if (partials[j].layer == coalesced_geometry[i].layer && partials[j].t == coalesced_geometry[i].t) {
+					for (size_t k = 0; k < coalesced_geometry[i].geometry.size(); k++) {
+						partials[j].geoms[0].push_back(coalesced_geometry[i].geometry[k]);
+					}
+
+					coalesced_geometry.erase(coalesced_geometry.begin() + i);
+					break;
+				}
+			}
+		}
+
 		if (prefilter != NULL) {
 			json_end(prefilter_jp);
 			if (fclose(prefilter_read_fp) != 0) {

version.hpp

@@ -1,6 +1,6 @@
 #ifndef VERSION_HPP
 #define VERSION_HPP
 
-#define VERSION "tippecanoe v1.24.1\n"
+#define VERSION "tippecanoe v1.25.0\n"
 
 #endif