From 58ab638f20b13a00b05b579e8f8f4783ebdbf9a1 Mon Sep 17 00:00:00 2001
From: Eric Fischer <enf@pobox.com>
Date: Mon, 18 Jun 2018 09:41:26 -0700
Subject: [PATCH] Debugging code to find where I am leaving empty linetos

---
 vt3.cpp | 74 ++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 71 insertions(+), 3 deletions(-)

diff --git a/vt3.cpp b/vt3.cpp
index 19e8fcf..5434e09 100644
--- a/vt3.cpp
+++ b/vt3.cpp
@@ -23,6 +23,15 @@
 #include "vt3.hpp"
 #include "clip.hpp"
 
+bool check_empty_lineto(std::vector<mvt_geometry> &geom) {
+	for (size_t i = 1; i < geom.size(); i++) {
+		if (geom[i].op == mvt_lineto && geom[i - 1].x == geom[i].x && geom[i - 1].y == geom[i].y) {
+			return true;
+		}
+	}
+	return false;
+}
+
 std::vector<mvt_geometry> clip_lines(std::vector<mvt_geometry> &geom, long left, long top, long right, long bottom) {
 	std::vector<mvt_geometry> out;
 
@@ -64,6 +73,10 @@ std::vector<mvt_geometry> clip_lines(std::vector<mvt_geometry> &geom, long left,
 					phantom.id = 0;
 					out.push_back(phantom);
 					out.push_back(geom[i]);
+
+					if (phantom == geom[i]) {
+						fprintf(stderr, "clip out to in made empty lineto\n");
+					}
 				}
 
 				inside = true;
@@ -88,9 +101,20 @@ std::vector<mvt_geometry> clip_lines(std::vector<mvt_geometry> &geom, long left,
 					// out.push_back(geom[i - 1]);
 
 					mvt_geometry phantom(mvt_lineto, round(x2), round(y2));
-					phantom.phantom = true;
-					phantom.id = 0;
-					out.push_back(phantom);
+
+					if (phantom == out[out.size() - 1]) {
+						if (out[out.size() - 1].id == 0) {
+							fprintf(stderr, "In to out is clipped away but has no id %lld,%lld\n", phantom.x, phantom.y);
+						}
+					} else {
+						phantom.phantom = true;
+						phantom.id = 0;
+						out.push_back(phantom);
+					}
+
+					if (out[out.size() - 2] == out[out.size() - 1]) {
+						fprintf(stderr, "clip in to out made empty lineto\n");
+					}
 				} else {
 					// Outside to outside, so discardable on both sides
 
@@ -112,6 +136,10 @@ std::vector<mvt_geometry> clip_lines(std::vector<mvt_geometry> &geom, long left,
 						phantom2.phantom = true;
 						phantom2.id = 0;
 						out.push_back(phantom2);
+
+						if (phantom1 == phantom2) {
+							fprintf(stderr, "clip in discardable made empty lineto\n");
+						}
 					}
 				}
 
@@ -120,6 +148,11 @@ std::vector<mvt_geometry> clip_lines(std::vector<mvt_geometry> &geom, long left,
 		}
 	}
 
+	if (check_empty_lineto(out)) {
+		fprintf(stderr, "empty lineto in clip\n");
+		exit(EXIT_FAILURE);
+	}
+
 	return out;
 }
 
@@ -149,6 +182,11 @@ static std::vector<mvt_geometry> remove_noop(std::vector<mvt_geometry> geom, std
 		}
 	}
 
+	if (check_empty_lineto(out)) {
+		fprintf(stderr, "empty lineto in remove noop\n");
+		exit(EXIT_FAILURE);
+	}
+
 	return out;
 }
 
@@ -285,6 +323,11 @@ void split_feature(mvt_layer const &layer, mvt_feature const &feature, std::vect
 			ngeom.push_back(ogeom[i]);
 		}
 
+		if (check_empty_lineto(ngeom)) {
+			fprintf(stderr, "empty lineto in adding crossings\n");
+			exit(EXIT_FAILURE);
+		}
+
 		// Part 1a: same, but for Y axis crossings
 
 		ogeom = ngeom;
@@ -320,6 +363,11 @@ void split_feature(mvt_layer const &layer, mvt_feature const &feature, std::vect
 			ngeom.push_back(ogeom[i]);
 		}
 
+		if (check_empty_lineto(ngeom)) {
+			fprintf(stderr, "empty lineto in adding crossings\n");
+			exit(EXIT_FAILURE);
+		}
+
 		// Part 2: Assign (real) point IDs for any points that are on a sub-tile edge
 		for (size_t i = 0; i < ngeom.size(); i++) {
 			if (ngeom[i].x % nextent == 0 || ngeom[i].y % nextent == 0) {
@@ -427,6 +475,11 @@ void merge_partials(std::vector<partial> &partials, size_t start, size_t end, mv
 					out.push_back(geom[k]);
 				}
 
+				if (check_empty_lineto(out)) {
+					fprintf(stderr, "empty lineto in buffer removal 1\n");
+					exit(EXIT_FAILURE);
+				}
+
 				// Now need to discard anything that happens in the buffer,
 				// because it should all be duplicated.
 
@@ -453,6 +506,11 @@ void merge_partials(std::vector<partial> &partials, size_t start, size_t end, mv
 					}
 				}
 
+				if (check_empty_lineto(out2)) {
+					fprintf(stderr, "empty lineto in buffer removal\n");
+					exit(EXIT_FAILURE);
+				}
+
 				revised.push_back(out2);
 				j = k - 1;
 			}
@@ -498,6 +556,11 @@ void merge_partials(std::vector<partial> &partials, size_t start, size_t end, mv
 				}
 			}
 
+			if (check_empty_lineto(arc)) {
+				fprintf(stderr, "empty lineto in arc making\n");
+				exit(EXIT_FAILURE);
+			}
+
 			// Don't insert anything that was clipped down to just one moveto
 			if (arc.size() > 1) {
 				arcs.insert(std::pair<long, std::vector<mvt_geometry>>(id, arc));
@@ -560,6 +623,11 @@ void merge_partials(std::vector<partial> &partials, size_t start, size_t end, mv
 			}
 		}
 
+		if (check_empty_lineto(out)) {
+			fprintf(stderr, "empty lineto in reassembly\n");
+			exit(EXIT_FAILURE);
+		}
+
 		for (size_t i = 0; i < out.size(); i++) {
 			nf->geometry.push_back(out[i]);
 		}