From a9c396a8ce2037eb660360c7ee4c69187dcf418e Mon Sep 17 00:00:00 2001
From: Christoph Oelckers <coelckers@zdoom.fake>
Date: Sun, 3 May 2009 21:12:52 +0000
Subject: [PATCH] - fixed: The CHECKSWITCHRANGE line flag was ignored for one
 sided lines.

SVN r1570 (trunk)
---
 docs/rh-log.txt  |  1 +
 src/p_switch.cpp | 14 +++++++++++---
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/docs/rh-log.txt b/docs/rh-log.txt
index 465929870..47c641c18 100644
--- a/docs/rh-log.txt
+++ b/docs/rh-log.txt
@@ -1,4 +1,5 @@
 May 3, 2009  (Changes by Graf Zahl)
+- fixed: The CHECKSWITCHRANGE line flag was ignored for one sided lines.
 - Added more compatibility settings, submitted by Gez.
 
 May 2, 2009  (Changes by Graf Zahl)
diff --git a/src/p_switch.cpp b/src/p_switch.cpp
index 9eb0ec6a2..1d31e8c38 100644
--- a/src/p_switch.cpp
+++ b/src/p_switch.cpp
@@ -464,8 +464,7 @@ static int TryFindSwitch (side_t *side, int Where)
 //
 bool P_CheckSwitchRange(AActor *user, line_t *line, int sideno)
 {
-	// if this line is one sided this function must always return success.
-	if (line->sidenum[0] == NO_SIDE || line->sidenum[1] == NO_SIDE) return true;
+	if (line->sidenum[0] == NO_SIDE) return true;
 
 	fixed_t checktop;
 	fixed_t checkbot;
@@ -492,9 +491,18 @@ bool P_CheckSwitchRange(AActor *user, line_t *line, int sideno)
 	checkx = dll.x + FixedMul(dll.dx, inter);
 	checky = dll.y + FixedMul(dll.dy, inter);
 
+	// one sided line
+	if (line->sidenum[1] == NO_SIDE) 
+	{
+	onesided:
+		fixed_t sectorc = line->frontsector->ceilingplane.ZatPoint(checkx, checky);
+		fixed_t sectorf = line->frontsector->floorplane.ZatPoint(checkx, checky);
+		return (user->z + user->height >= sectorf && user->z <= sectorc);
+	}
+
 	// Now get the information from the line.
 	P_LineOpening(open, NULL, line, checkx, checky, user->x, user->y);
-	if (open.range <= 0) return true;
+	if (open.range <= 0) goto onesided;
 
 	if ((TryFindSwitch (side, side_t::top)) != -1)
 	{