From 93eabd1b4f4229da8f01ece604f457418bd23726 Mon Sep 17 00:00:00 2001
From: Simon <simonbrown77@googlemail.com>
Date: Tue, 27 Jun 2023 23:35:57 +0100
Subject: [PATCH] Fix crash when clipping through into non-sector areas

---
 source/core/rendering/hw_entrypoint.cpp | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/source/core/rendering/hw_entrypoint.cpp b/source/core/rendering/hw_entrypoint.cpp
index 5a82bcfbe..b8ea39d58 100644
--- a/source/core/rendering/hw_entrypoint.cpp
+++ b/source/core/rendering/hw_entrypoint.cpp
@@ -176,10 +176,15 @@ void RenderViewpoint(FRenderViewpoint& mainvp, IntRect* bounds, float fov, float
 		// Stereo mode specific viewpoint adjustment
 		if (eye.mShiftFactor != 0)
 		{
-			vp.Pos += eye.GetViewShift(vp.HWAngles);
+			DVector3 newpos = vp.Pos;
+			newpos += eye.GetViewShift(vp.HWAngles);
 			sectortype* sect = &sector[vp.SectCount];
-			updatesector(DVector2(vp.Pos.X, -vp.Pos.Y), &sect);
-			vp.SectCount = sectindex(sect);
+			updatesector(DVector2(newpos.X, -newpos.Y), &sect);
+			if (sect != nullptr)
+			{
+				vp.Pos = newpos;
+				vp.SectCount = sectindex(sect);
+			}
 		}
 
 		di->SetupView(RenderState, vp.Pos.X, vp.Pos.Y, vp.Pos.Z, false, false);