From 4ed8b69e2455637e50d96dd1db0f12fe582e6e33 Mon Sep 17 00:00:00 2001
From: Bill Currie <bill@taniwha.org>
Date: Wed, 7 Dec 2011 12:20:04 +0900
Subject: [PATCH] Check the cross product length before testing its direction.

This fixes the bogus portal crossings.
---
 libs/models/trace.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libs/models/trace.c b/libs/models/trace.c
index a727332ed..a3e66dc21 100644
--- a/libs/models/trace.c
+++ b/libs/models/trace.c
@@ -211,6 +211,8 @@ point_inside_portal (const clipport_t *portal, const plane_t *plane,
 	for (i = 0; i < points->numpoints; i++) {
 		VectorSubtract (p, points->points[i], x);
 		CrossProduct (x, edges->points[i], c);
+		if (DotProduct (c, c) < PLANE_EPSILON)
+			return false;
 		if (DotProduct (c, n) <= 0)
 			return false;
 	}