Add point retention multiplier (#179)

* Add an option to retain N times as many points as usual at each zoom

* Tests for point multipler with specified and guessed maxzooms

* Work in progress on inverse spatial ordering

* Fix inverse spatial feature order

* --reorder was depending on a feature index that wasn't being preserved

* Separate ordering by feature_minzoom from ordering inverse-spatially

* Add a test for the inverse spatial ordering

* Store the basezoom/droprate/multiplier decisions in tileset metadata

* Progress on adding filters to tippecanoe-overzoom

* Type promotion for comparison

* Look up the attribute value for ordering

* Add test of thinning and ordering features

* Plumb tippecanoe_decisions metadata through pmtiles

* Be careful not to put infinities in JSON

* Fix accidental dropping in what is meant to preserve sparse points

* Start distinguishing true, false, and null in expressions

* Most of the type conversions

* Add boolean conversions

* Literals and conjunctions

* Add filtering to tippecanoe-overzoom

* Add a test of filtering in overzoom

* Fix boolean conjunctions

* Handle the combination of cluster size and filtering

* Rework dot dropping to reconcile density threshold and multiplier

* Revert "Rework dot dropping to reconcile density threshold and multiplier"

This reverts commit f253a66382.

* Retain points by multiplier within each tile, not in global probability

* Test that intends to verify that the multiplier is reversible

* Get the test to detect the discrepancy

* Mark the start of multiplier clusters with a magic attribute

* Add string-contains

* Add in and ni operators

* Revert "Look up the attribute value for ordering"

This reverts commit 56bc73e49a.

* Revert "Type promotion for comparison"

This reverts commit 6f3256f5af.

* Make number formatting in tippecanoe_decisions consistent

* Revert "Add a test for the inverse spatial ordering"

This reverts commit c8047de9ab.

* Revert "Separate ordering by feature_minzoom from ordering inverse-spatially"

This reverts commit 35b19a223c.

* Revert "Fix inverse spatial feature order"

This reverts commit 5978ecdb44.

* Revert "Work in progress on inverse spatial ordering"

This reverts commit fdf230f632.

* Somehow missed the tests associated with that last revert

* Round-robin assign attributes to partials from across the multiplier

* Count the multiplier separately in each layer

* Fix distribution of accumulated attribute across multiplier features

* Update changelog, version, and docs

* Add "is null" and "isnt null" expressions

* Update interpretation of FSL expressions to pass the tests

* Test to assert that polygons are unaffected by the multiplier

* Clean up and comment

* Remove accidental unused case

overzoom.cpp

@@ -6,12 +6,15 @@
 #include "errors.hpp"
 #include "mvt.hpp"
 #include "geometry.hpp"
+#include "evaluator.hpp"
 
 extern char *optarg;
 extern int optind;
 
 int detail = 12;  // tippecanoe-style: mvt extent == 1 << detail
 int buffer = 5;	  // tippecanoe-style: mvt buffer == extent * buffer / 256;
+bool demultiply = false;
+std::string filter;
 
 std::set<std::string> keep;
 
@@ -25,7 +28,7 @@ int main(int argc, char **argv) {
 	int i;
 	const char *outfile = NULL;
 
-	while ((i = getopt(argc, argv, "y:o:d:b:")) != -1) {
+	while ((i = getopt(argc, argv, "y:d:b:o:mj:")) != -1) {
 		switch (i) {
 		case 'y':
 			keep.insert(optarg);
@@ -43,7 +46,16 @@ int main(int argc, char **argv) {
 			buffer = atoi(optarg);
 			break;
 
+		case 'm':
+			demultiply = true;
+			break;
+
+		case 'j':
+			filter = optarg;
+			break;
+
 		default:
+			fprintf(stderr, "Unrecognized flag -%c\n", i);
 			usage(argv);
 		}
 	}
@@ -91,7 +103,12 @@ int main(int argc, char **argv) {
 		exit(EXIT_FAILURE);
 	}
 
-	std::string out = overzoom(tile, oz, ox, oy, nz, nx, ny, detail, buffer, keep, true, NULL);
+	json_object *json_filter = NULL;
+	if (filter.size() > 0) {
+		json_filter = parse_filter(filter.c_str());
+	}
+
+	std::string out = overzoom(tile, oz, ox, oy, nz, nx, ny, detail, buffer, keep, true, NULL, demultiply, json_filter);
 	fwrite(out.c_str(), sizeof(char), out.size(), f);
 	fclose(f);