From 4568bbae11d891830378af49ed0fa9b29f740a39 Mon Sep 17 00:00:00 2001
From: Chris Taylor <chris@icculus.org>
Date: Sat, 12 Nov 2016 16:41:54 +0800
Subject: [PATCH] Don't crash when building segment bridge in editor the wrong
 way

Check if there is Markedsegp and replacing an Assert with a LevelError.
---
 similar/editor/kbuild.cpp | 5 +++++
 similar/main/gameseg.cpp  | 3 ++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/similar/editor/kbuild.cpp b/similar/editor/kbuild.cpp
index 17d4019cc..51da3a441 100644
--- a/similar/editor/kbuild.cpp
+++ b/similar/editor/kbuild.cpp
@@ -35,6 +35,11 @@ COPYRIGHT 1993-1998 PARALLAX SOFTWARE CORPORATION.  ALL RIGHTS RESERVED.
 //  ---------- Create a bridge segment between current segment/side and marked segment/side ----------
 int CreateBridge()
 {
+	if (!Markedsegp) {
+		editor_status("No marked side.");
+		return 0;
+	}
+	
     if (!med_form_bridge_segment(Cursegp,Curside,Markedsegp,Markedside)) {
 		Update_flags |= UF_WORLD_CHANGED;
 		mine_changed = 1;
diff --git a/similar/main/gameseg.cpp b/similar/main/gameseg.cpp
index 619938717..d8d20de58 100644
--- a/similar/main/gameseg.cpp
+++ b/similar/main/gameseg.cpp
@@ -1277,7 +1277,8 @@ static void get_verts_for_normal(int va, int vb, int vc, int vd, int *v0, int *v
 				swap(w[j], w[i]);
 			}
 
-	Assert((v[0] < v[1]) && (v[1] < v[2]) && (v[2] < v[3]));
+	if (!((v[0] < v[1]) && (v[1] < v[2]) && (v[2] < v[3])))
+		LevelError("Level contains malformed geometry.");
 
 	//	Now, if for any w[i] & w[i+1]: w[i+1] = (w[i]+3)%4, then must swap
 	*v0 = v[0];