From 7bb79dab8e48bd0558c0d291d8463201543e19f1 Mon Sep 17 00:00:00 2001
From: Eric Fischer <enf@pobox.com>
Date: Tue, 23 Sep 2014 10:37:18 -0700
Subject: [PATCH] Optimize away deltas of 0

---
 tile.cc | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/tile.cc b/tile.cc
index a2a390e..e004d71 100644
--- a/tile.cc
+++ b/tile.cc
@@ -130,12 +130,14 @@ void write_tile(struct index *start, struct index *end, char *metabase, unsigned
 				int dx = wwx - px;
 				int dy = wwy - py;
 
-				feature->add_geometry((dx << 1) ^ (dx >> 31));
-				feature->add_geometry((dy << 1) ^ (dy >> 31));
+				if (dx != 0 || dy != 0 || length == 0) {
+					feature->add_geometry((dx << 1) ^ (dx >> 31));
+					feature->add_geometry((dy << 1) ^ (dy >> 31));
 
-				px = wwx;
-				py = wwy;
-				length++;
+					px = wwx;
+					py = wwy;
+					length++;
+				}
 
 				//printf("%lld,%lld ", wwx, wwy);
 			} else if (op == VT_CLOSEPATH) {