From 5844c989bd052a41f833a24802260b830123ab51 Mon Sep 17 00:00:00 2001
From: Keith OHara <k-ohara5a5a@oco.net>
Date: Fri, 23 Aug 2013 23:13:40 -0700
Subject: [PATCH] Skylines: reject steep-sloped buildings; issue 3383

---
 lily/skyline.cc | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/lily/skyline.cc b/lily/skyline.cc
index 8654f0d973..70bf989861 100644
--- a/lily/skyline.cc
+++ b/lily/skyline.cc
@@ -125,6 +125,12 @@ Building::precompute (Real start, Real start_height, Real end_height, Real end)
       assert (start_height == end_height);
       y_intercept_ = start_height;
     }
+  else if (fabs(slope_) > 1e6)
+    // too steep to be stored in slope-intercept form, given round-off error
+    {
+      slope_ = 0.0;
+      y_intercept_ = max(start_height, end_height);
+    }
   else
     y_intercept_ = start_height - slope_ * start;
 }
-- 
2.39.5