From ddbb8d79c1535ab3beca146e9d08ae4178043a2c Mon Sep 17 00:00:00 2001
From: Christoph Oelckers <coelckers@zdoom.fake>
Date: Thu, 7 Apr 2016 21:13:37 +0200
Subject: [PATCH] - handle the player sprite when crossing a portal.

---
 src/gl/scene/gl_portal.cpp | 21 +++++++++++++++++++++
 src/gl/scene/gl_portal.h   |  1 +
 2 files changed, 22 insertions(+)

diff --git a/src/gl/scene/gl_portal.cpp b/src/gl/scene/gl_portal.cpp
index 7aaf04a77d..74af305c36 100644
--- a/src/gl/scene/gl_portal.cpp
+++ b/src/gl/scene/gl_portal.cpp
@@ -312,6 +312,8 @@ bool GLPortal::Start(bool usestencil, bool doquery)
 	savedviewactor=GLRenderer->mViewActor;
 	savedviewarea=in_area;
 	savedshowviewer = r_showviewer;
+	savedviewpath[0] = ViewPath[0];
+	savedviewpath[1] = ViewPath[1];
 
 	NextPortal = GLRenderer->mCurrentPortal;
 	GLRenderer->mCurrentPortal = NULL;	// Portals which need this have to set it themselves
@@ -374,6 +376,8 @@ void GLPortal::End(bool usestencil)
 		if (needdepth) FDrawInfo::EndDrawInfo();
 
 		// Restore the old view
+		ViewPath[0] = savedviewpath[0];
+		ViewPath[1] = savedviewpath[1];
 		ViewPos = savedViewPos;
 		ViewAngle = savedAngle;
 		GLRenderer->mViewActor=savedviewactor;
@@ -992,6 +996,23 @@ void GLLineToLinePortal::DrawContents()
 	P_TranslatePortalXY(origin, ViewPos.X, ViewPos.Y);
 	P_TranslatePortalAngle(origin, ViewAngle);
 	P_TranslatePortalZ(origin, ViewPos.Z);
+	P_TranslatePortalXY(origin, ViewPath[0].X, ViewPath[0].Y);
+	P_TranslatePortalXY(origin, ViewPath[1].X, ViewPath[1].Y);
+	if (!r_showviewer)
+	{
+		double distp = (ViewPath[0] - ViewPath[1]).Length();
+		if (distp > EQUAL_EPSILON)
+		{
+			double dist1 = (ViewPos - ViewPath[0]).Length();
+			double dist2 = (ViewPos - ViewPath[1]).Length();
+
+			if (dist1 + dist2 > distp + 1)
+			{
+				r_showviewer = true;
+			}
+		}
+	}
+
 
 	SaveMapSection();
 
diff --git a/src/gl/scene/gl_portal.h b/src/gl/scene/gl_portal.h
index 47e8dcedbe..d8c5da6193 100644
--- a/src/gl/scene/gl_portal.h
+++ b/src/gl/scene/gl_portal.h
@@ -106,6 +106,7 @@ private:
 	AActor * savedviewactor;
 	area_t savedviewarea;
 	bool savedshowviewer;
+	DVector3 savedviewpath[2];
 	GLPortal *NextPortal;
 	TArray<BYTE> savedmapsection;
 	TArray<unsigned int> mPrimIndices;