From 1de4f9c3cc9e5c6668991abd76b8263eaf04a78b Mon Sep 17 00:00:00 2001
From: Zach Fox <fox@highfidelity.io>
Date: Thu, 8 Nov 2018 13:07:49 -0800
Subject: [PATCH] Correct portal math

---
 interface/src/Application.cpp     | 2 ++
 interface/src/SecondaryCamera.cpp | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/interface/src/Application.cpp b/interface/src/Application.cpp
index 926df2943e..abe9d8a053 100644
--- a/interface/src/Application.cpp
+++ b/interface/src/Application.cpp
@@ -5608,6 +5608,8 @@ void Application::updateSecondaryCameraViewFrustum() {
 
         glm::vec3 mainCameraPositionWorld = getCamera().getPosition();
         glm::vec3 mainCameraPositionPortalEntrance = vec3(portalEntranceFromWorld * vec4(mainCameraPositionWorld, 1.0f));
+        mainCameraPositionPortalEntrance = vec3(-mainCameraPositionPortalEntrance.x, mainCameraPositionPortalEntrance.y,
+            -mainCameraPositionPortalEntrance.z);
         glm::vec3 portalExitCameraPositionWorld = vec3(worldFromPortalExit * vec4(mainCameraPositionPortalEntrance, 1.0f));
 
         secondaryViewFrustum.setPosition(portalExitCameraPositionWorld);
diff --git a/interface/src/SecondaryCamera.cpp b/interface/src/SecondaryCamera.cpp
index ea485ebf40..aa5d9d7f58 100644
--- a/interface/src/SecondaryCamera.cpp
+++ b/interface/src/SecondaryCamera.cpp
@@ -81,6 +81,8 @@ public:
 
         glm::vec3 mainCameraPositionWorld = qApp->getCamera().getPosition();
         glm::vec3 mainCameraPositionPortalEntrance = vec3(portalEntranceFromWorld * vec4(mainCameraPositionWorld, 1.0f));
+        mainCameraPositionPortalEntrance = vec3(-mainCameraPositionPortalEntrance.x, mainCameraPositionPortalEntrance.y,
+            -mainCameraPositionPortalEntrance.z);
         glm::vec3 portalExitCameraPositionWorld = vec3(worldFromPortalExit * vec4(mainCameraPositionPortalEntrance, 1.0f));
 
         srcViewFrustum.setPosition(portalExitCameraPositionWorld);