Add --generate-variable-depth-tile-pyramid option (#251)

* Track output position at the file level instead of within each tile

* Track file position where the child tile data begins

* Add option and document its intended behavior

* Changing the detail loop to account for stopping early

* I forgot I already added an option for this

* Stop early if we can make a complete tile

* Add a test of zoom truncation with limited feature count

* Forgot to commit the actual code change

* Make room for a vertex count in the header of each serialized tile

* Estimate tile complexity; don't try truncating when unlikely to work

* Be more conservative, because ever retrying a tile is a big speed hit

* If stopping early, don't simplify or clean; leave that to overzoom

* Add tiny polygon reduction / dust to overzoom

* Don't try to stop early in the children if we dropped anything by rate

* Fflush here too before pwriting

* Don't stop early if we ended up dropping any features.

Rework the can-the-next-zoom-stop-early logic to avoid going
one zoom further than needed.

* Fix warning

* Fix warnings

* Oops, checking for the wrong expected return value

* Cleanup from adding line simplification in overzoom

* Current (wrong) behavior when combining coalescing and truncating

* Keep a list of parent tiles to skip rather than truncating

* Now the coalesced tiles in z12 get children in z13

* Don't double-count feature dropping when the zoom level is retried

* Correct README description

* Remove todo about special case below basezoom, which is accounted for

* Be a little more aggressive in drop-densest determination

* Scale tile feature limit for megatiles in the same way as byte limit

* Fully deprecate -detect-shared-borders into an alias

* Track the distances found in the douglas-peucker recursion

* Serialize and deserialize the distance with the vertices

* Revert "Serialize and deserialize the distance with the vertices"

This reverts commit 753f1b7909.

* Revert "Track the distances found in the douglas-peucker recursion"

This reverts commit e5361f8c22.

* Revert "Fully deprecate -detect-shared-borders into an alias"

This reverts commit 0698aeb766.

* Better tracking of whether we failed to make a full-detail tile

* Put a bloom filter in front of the binary search for shared nodes

* Forgot to take out this printf

* Improve dispatch of tiling tasks

* Still dispatch the biggest tasks first

* Track zoom truncation in the strategies list in the tileset metadata

* Prescan for small deltas before doing proper simplification

* Revert "Prescan for small deltas before doing proper simplification"

This reverts commit d1d8238b83.

* Update version and changelog

* Rename to --generate-variable-depth-tile-pyramid

overzoom.cpp

@@ -35,6 +35,8 @@ int main(int argc, char **argv) {
 	int i;
 	const char *outtile = NULL;
 	const char *outfile = NULL;
+	double simplification = 0;
+	double tiny_polygon_size = 0;
 
 	std::vector<input_tile> sources;
 
@@ -48,6 +50,8 @@ int main(int argc, char **argv) {
 		{"preserve-input-order", no_argument, 0, 'o' & 0x1F},
 		{"accumulate-attribute", required_argument, 0, 'E'},
 		{"unidecode-data", required_argument, 0, 'u' & 0x1F},
+		{"line-simplification", required_argument, 0, 'S'},
+		{"tiny-polygon-size", required_argument, 0, 's' & 0x1F},
 		{"source-tile", required_argument, 0, 't'},
 
 		{0, 0, 0, 0},
@@ -107,6 +111,14 @@ int main(int argc, char **argv) {
 			outtile = optarg;
 			break;
 
+		case 's' & 0x1F:
+			tiny_polygon_size = atof(optarg);
+			break;
+
+		case 'S':
+			simplification = atof(optarg);
+			break;
+
 		default:
 			fprintf(stderr, "Unrecognized flag -%c\n", i);
 			usage(argv);
@@ -196,7 +208,7 @@ int main(int argc, char **argv) {
 		its.push_back(std::move(t));
 	}
 
-	std::string out = overzoom(its, nz, nx, ny, detail, buffer, keep, true, NULL, demultiply, json_filter, preserve_input_order, attribute_accum, unidecode_data);
+	std::string out = overzoom(its, nz, nx, ny, detail, buffer, keep, true, NULL, demultiply, json_filter, preserve_input_order, attribute_accum, unidecode_data, simplification, tiny_polygon_size);
 
 	FILE *f = fopen(outfile, "wb");
 	if (f == NULL) {