From 966e6797e49061093a5a28a0b28edaee5bb0b59a Mon Sep 17 00:00:00 2001
From: Christoph Oelckers <c.oelckers@zdoom.fake>
Date: Mon, 9 May 2016 23:16:06 +0200
Subject: [PATCH] - fixed: The view path for checking whether the player sprite
 should be drawn during a portal transition was never set properly in the
 portal transitioning case.

---
 src/r_main.cpp    |  3 ++-
 src/r_utility.cpp |  4 ++--
 src/vectors.h     | 10 ++++++++++
 3 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/src/r_main.cpp b/src/r_main.cpp
index 58e94e5445..ce4841a2e7 100644
--- a/src/r_main.cpp
+++ b/src/r_main.cpp
@@ -58,6 +58,7 @@
 #include "v_font.h"
 #include "r_data/colormaps.h"
 #include "farchive.h"
+#include "p_maputl.h"
 
 // MACROS ------------------------------------------------------------------
 
@@ -687,7 +688,7 @@ void R_EnterPortal (PortalDrawseg* pds, int depth)
 		P_TranslatePortalXY(pds->src, ViewPath[0].X, ViewPath[0].Y);
 		P_TranslatePortalXY(pds->src, ViewPath[1].X, ViewPath[1].Y);
 
-		if (!r_showviewer && camera)
+		if (!r_showviewer && camera && P_PointOnLineSidePrecise(ViewPath[0], pds->dst) != P_PointOnLineSidePrecise(ViewPath[1], pds->dst))
 		{
 			double distp = (ViewPath[0] - ViewPath[1]).Length();
 			if (distp > EQUAL_EPSILON)
diff --git a/src/r_utility.cpp b/src/r_utility.cpp
index 701a3cffd3..71d3f23769 100644
--- a/src/r_utility.cpp
+++ b/src/r_utility.cpp
@@ -433,14 +433,14 @@ void R_InterpolateView (player_t *player, double Frac, InterpolationViewer *ivie
 				}
 				InterpolationPath.Pop();
 				ViewPath[0] = iview->Old.Pos;
+				ViewPath[1] = ViewPath[0] + (InterpolationPath[0].pos - ViewPath[0]).XY().MakeResize(pathlen);
 			}
 		}
 		else
 		{
 			DVector2 disp = Displacements.getOffset(oldgroup, newgroup);
 			ViewPos = iview->Old.Pos + (iview->New.Pos - iview->Old.Pos - disp) * Frac;
-			ViewPath[1] = iview->New.Pos;
-			ViewPath[0] = iview->Old.Pos;
+			ViewPath[0] = ViewPath[1] = iview->New.Pos;
 		}
 	}
 	else
diff --git a/src/vectors.h b/src/vectors.h
index caa9c2f206..00a65df507 100644
--- a/src/vectors.h
+++ b/src/vectors.h
@@ -260,6 +260,16 @@ struct TVector2
 		return len;
 	}
 
+	// Resizes this vector to be the specified length (if it is not 0)
+	TVector2 &MakeResize(double len)
+	{
+		double scale = len / Length();
+		X = vec_t(X * scale);
+		Y = vec_t(Y * scale);
+		return *this;
+	}
+
+
 	// Dot product
 	double operator | (const TVector2 &other) const
 	{